SolarPro Magazine.pdf - Contractors Institute

Plug into Solar PowerSMBecome agroSolar dealerand join America’s premier solar network.Deliver your customers the world class service, premium products, industry intelligence and engineeringexpertise of groSolar. Position your business for success by becoming a groSolar dealer and tapping intothe Nation’s premier solar power company. Along with our partners we’ve been pioneering solar for almost30 years. Get so much more than quality products. Empower your customers to enjoy the financial benefitsof solar power and become a dealer of the Nation’s leading solar power solutions.We’ve learned a few things along the way:• The most warehouses in North America equals better service• The value of industry-leading training programs• Our exclusive PanelClaw flat roof mounting system• Quick access to more products with less shipping• Engineering and installation support that makes it easyAbout groSolargroSolar is North America’s premier distributor, installer and integrator of solarenergy solutions for residential and commercial installations. Founded in 1998,groSolar is the largest 100 percent U.S.-owned distribution company in the solarindustry. The company has offices and warehouses across the US, distributingsolar electric and solar hot water systems from offices in VT, NJ, NY, CT, MA,MD, DE, PA, CO, MT, and CA.866.GRO.SOLARgroSolar.com/hot

SMA_WHEEL_SPIBUG_AUS093011www.SMA-America.comWhat would a solar power system bewithout SMA inverters?Would it make sense to leave out the most important component of your solar system? Of course not.The solar inverter is the heart of every solar power system and its performance is essential to yourreturn-on-investment. SMA is the world‘s largest manufacturer of solar inverters and builds the mosttechnologically advanced inverters available. When you consider the industry-leading efficiency,the variety of sizes, the versatility of grid-tied or off-grid use, and compatibility with all types of solarmodules, SMA is your only logical choice.SMA Inverters: Ask for them by name.Visit us atSolar Power InternationalBooTh #1421The Future of Solar Technology

SC500USHIPNOWSPIBUG-AUS092720www.SMA-America.comThe biggest name in solar inverters just got bigger.Meet the new Sunny Central 500U.Today’s solar power plants are getting larger and customer demands are getting tougher. Choosingthe new Sunny Central 500U means you’re backed by over 25 years of industry experience.Combine that with world-class German engineering and stand behind your work with confi dence.The new Sunny Central 500U features industry-leading technology with powerful options suchas smart combiner boxes and Modbus ® capability. Your customers expect the best. Rely on SMAto help you deliver.The Sunny Central 500U. Ask for it by name.Call 888 476 2872Visit us atSolar Power InternationalBOOTH #1421The Future of Solar Technology

Contents 2October/November 2009 Issue 2.620DepartmentsFRONT END10 Contributors Experience + Expertise14 Q & A Technical Questions & AnswersNew PTC Ratings | Compliance with Article690.31(A) of the 2008 NEC20 The Wire Industry Currents8214BACK END82 Interview An Experienced PerspectiveBlake Jones, Namasté Solar90 Training Continuing Education for the Pro9292 Projects System ProfilesPearl Brewery, Full Goods Building,San Antonio, TXHabitat for Heroes, San Juan Capistrano, CA95 Advertiser Indexf On the Cover Sun Light & Power’s Blake Gleason takes megohm measurements at an AMtec combiner duringsystem commissioning at Berkeley Bowl West in Berkeley, CA. Photo by Shawn Schreiner8 SOLARPRO | October/November 2009

AEE Solar is the exclusive North American wholesale distributor of solar modulesfrom Norway-based REC, the world's most integrated solar energy company.FROM KILOWATTS TO MEGAWATTS...HUGE SALE on REC AE-US Solar ModulesWe will beat any verifiable, written offer onmodules of comparable size and quality.REC modules are BuyAmerican Act compliant.To get a quote for yourresidential or commercialproject, call 866-717-6527.If you are already an AEE Solar dealer,have your dealer number ready.If you are not yet an AEE Solar dealerbut you are a licensed contractor,solar dealer or PV installer, ask forthe "REC module sale".AEE Solar sells only to licensed solarinstallers and resellers. If you areinterested in top-quality REC solarpanels for your home or business,please contact us for a dealer near you.To make room for the new blackframedAE-US modules coming fromREC in Q4 2009, we are offeringunprecedented prices on the 2ndgeneration silver-framed AE-USmodules – exactly the sameexcept the color of the frames.2nd GenerationREC AE-US PV module■ New junction box design■ Uses 100% American produced,high-grade polysilicon■ Manufactured in Scandinavia toexacting standards■ Acid-etched cells for higher energyyield; optimized for low light conditions■ 10-year 90%, 25-year 80% poweroutput warranty■ 63 months materials &workmanship warranty■ Available in sizes from 210 to 225 wattsThese prices are the best in the industry, regardless of the size of your installation.The bigger your project, the lower your price. Don't miss this opportunity!The Only Wholesale Distributor You’ll Ever Need www.aeesolar.com800-777-66098:30 to 5:00 Pacific TimeMonday-Friday707-923-2277707-923-3009 faxsales@aeesolar.com1155 Redway DrivePO Box 339Redway, CA 95560

ContributorsExperience + ExpertiseRon Burden has been working in the renewable energy industrysince 2003 as a PV system designer, installer and foreman ofresidential and large scale commercial projects. He is a graduateof the Energy Management Program at Lane Community Collegein Eugene, Oregon, and a NABCEP Certified Solar PV Installer.He holds a Limited Renewable Energy Technician license inOregon. He specializes in inverter topology and electrical codecompliance. Ron is a lead PV system design analyst with theCadmus Group in Portland, Oregon.Brian Crise is the lead instructor for the NECA-IBEW ElectricalTraining Center in Portland, Oregon. He has an Oregonsupervisor license, an Oregon electrical inspector certificationand is a NABCEP Certified Solar PV Installer. Brian hastaught PV classes both locally and nationally for electricians,inspectors and trainers. He is a member of the NFPA and theCode Making Panel that has had purview over NEC Article690 since 2002.Blake Gleason manages the engineering department at SunLight & Power, a 33-year-old solar design/build firm wherehe previously was a foreman and personally built more than100 residential and commercial PV systems. He possesses amaster’s degree in mechanical engineering, a California professionalengineer license and a California C-10 electrical license.He is a LEED accredited professional, a NABCEP CertifiedSolar PV Installer and a California certified journeyman electrician.He bikes to work in Berkeley, California.Boaz Soifer worked with Positive Energy, Dankoff Solar Productsand Local Energy before cofounding Cedar Mountain Solar(CMS) in Santa Fe, New Mexico, with Bristol Stickney in 2004.Under his direction, CMS, a national leader in solar heating contracting,has won many accolades including Small Business ofthe Year, a New Mexico Business Weekly “Fast-Tracker” awardand a System Showcase award from the RPA. Boaz also servesas CEO of SolarLogic and VP of the NM Renewable EnergyIndustry Association.Bristol Stickney is a well known authority in solar heating,with over 30 years in the industry. He worked with the NM SolarEnergy Association for more than 17 years; he has also workedwith Zomeworks, Coyne Solar Manufacturing and E-Source.A specialist in elegant controls to automate complex systems,Bristol holds a patent on a control system, SETH, thatsubstantially reduces electrical demand. He cofounded CMS,SolarLogic and the CMS solar thermal training center withBoaz Soifer.

SmartREThe revolutionary Smart Renewable Energy solution from OutBack Power, bringing you simplifiedgrid-tie solar with back-up power for residential and small commercial applications.Designed with an emphasis on ease of installation, the SmartRE solution installs and operatessimilarly to a regular grid-tie solar inverter but with the unique additional benefit of providingUPS quality battery back-up during utility outages. An integrated ultra-fast AC transfer switchguarantees that even sensitive back-up loads, like computers, never know when a utility outageoccurs. Matching outdoor/rainproof power electronics and battery enclosures constructed ofaluminum make the SmartRE a versatile product that can be installed both indoors or outdoors.Available in power levels up to 6kW and capable of providing as much as 69 kWh of back-uppower during outages, there is a SmartRE solution for your application.FLEXpower ONEThe new pre-wired FLEXpower ONE system includes all the essential protective devices in thesmallest possible space at the lowest installed cost.Utilizing the compact design of the FLEXware 250 enclosure, the fully pre-wired FLEXpowerONE system is designed for a quick and easy installation, saving both time and money. Usingthe new FLEXware 250 mounting plate the FLEXpower ONE system includes a single inverter,two FLEXware 250 enclosures, a single FLEXmax charge controller, a MATE, and a HUB4 in asmall footprint. The FLEXpower ONE system also includes the inverter and PV array breakers, PVground fault protection, an Input-Output-Bypass breaker assembly and either a US type GFCI(Type B) or a EU (Type F) AC outlet with one AC load breaker. The included hanging bracketmakes the FLEXpower One easy to install and hides all of the mounting hardware for a cleaner,more professional installation.The OutBack Power FLEXpower ONE system is the only choice when you need a fully integrated,true-sinewave, reliable power system that saves both time and money while still looking great.GTFX & GVFX LA SeriesThe new OutBack LA Series true sinewave grid interactive inverter/charger is designed for use in60 Hz countries outside of the US and Canada that have utility grids with nominal AC voltageshigher or lower than 120VAC.The LA series has been developed for areas that frequently experience high or low voltageconditions such as surges, spikes or brownouts, the LA Series grid reconnect timers have also beenshortened to improve system performance. Incorporating a DC to AC sinewave inverter, batterycharger and AC transfer the GTFX and GVFX LA Series Inverter/Chargers give you the ability to sellsolar, wind or hydro power back to the utility grid while providing back-up power in the event ofa utility outage. Our built in transfer switch automatically disconnects your loads from the utilitygrid and powers them from the inverter in the event of an outage, allowing you to continue usingyour solar and battery back-up power, unlike traditional battery-less grid-tie systems.

OURWORLDIS FULL OFENERGY10years ofConergyNearly 1 in every 10 of the world’s solar energy systems has been supplied, installed and/or developedby Conergy. In more than 15 countries on 4 continents, Conergy is driving innovation and marketcreation for solar energy. We are passionate about providing solar energy – a sustainable solution tomeet the world’s burgeoning power needs.Conergy provides end-to-end solutions for commercial enterprises, utilities, government, andagriculture clients with reliable, cost effective solar electric systems and serves a national networkof installers, developers and dealers with solutions for residential and small commercial markets.Our dedicated team of experienced professionals, relentless customer focus, innovative financing,and products ensure that projects backed by Conergy meet – and exceed – your expectations.Discover Solar Energy:www.conergy.us | info@conergy.us | (888) 396-6611Visit us at Solar Power International, Oct 27-29, Anaheim, CA, Booth #511

Q&AThe PTC operating cell temperatureis determined from the NOCT asfollows:T cell, PTC= 20 + 1.389 x(NOCT – 20) x (0.9 – η)The quantity (0.9 – η ) representsthe fraction of the sun’s energy hittingthe module that is converted into heat.It is assumed that 10% of the incomingenergy is reflected, which leaves 90%(0.9). Some of the energy is convertedinto electricity—that’s the whole pointof PV. The fraction converted intoelectricity is the module efficiency, η.The efficiency of a module can easilybe calculated from STC values. Thefollowing efficiency equation calculatesthe fraction of the sunlight hittingthe module that is converted to electricalpower:η = P STC÷ 1,000 W/m 2 ÷ areaOnce the PTC cell temperature isdetermined, the PTC power rating canbe calculated by derating the STC power.Use the temperature coefficient of power(C T) with the following equation:P PTC= P STCx [1 + C Tx (T cell, PTC− 25°C)]This is the PTC power value reportedby the California Energy Commission(CEC) on the Go Solar California Website (http://www.gosolarcalifornia.org/equipment/pvmodule.html) and is usedfor many incentive calculations in variousstates.Until July 1, 2009, the CEC calculatedand published PTC values basedon test data supplied by the modulemanufacturers. That is, the NOCT andtemperature coefficient of powerwere measured, estimated orextrapolated by manufacturers usingtheir own methods.As of July 1, 2009, the CEC lists PTCvalues calculated from data supplied bythird-party testing laboratories only—it no longer accepts manufacturersupplieddata. The testing labs are wellequipped to carefully reproduce theintended, identical test conditions andshould be impartial when reportingresults. Comparing the old PTC moduleratings (derived from manufacturersupplieddata) to the new PTC moduleratings (derived from independenttesting lab data), it appears that manymodule manufacturers may have beenoptimistic (see Figure 1 , p. 14). Thecurrent third-party testing requirementhelps ensure that capacity based incentivesmore accurately reflect operatingconditions in the field.—Blake Gleason / Sun Light & Power /Berkeley, CA / sunlightandpower.comCelebrating 15 Years of Service15 yearsSolar powerful!fast, easy PV mounting that lastsCombining photovoltaic arrays with standing seammetal roofing is made fast and easy with the S-5-PV Kit.Crystalline PV modules mounted with the S-5-PV Kitproduces a reliable 30-year alternative power source. Thepatented design of the attachment clamp and attendantround-point setscrew enables an entire installation without asingle penetration of the roof’s surface! If you want it strongwithout sacrificing your roof, this is the right way!A revolutionarynew solutionto attach solarPV panels tostanding seammetal roofs!For information call 800-284-1412 or visit www.lmcurbs.comVisit S-5! at www.S-5.com or call us at 888-825-343216 Solarpro | October/November 2009

Q&ACompliance with Article 690.31(A) of the2008 NECReadily accessible? To comply with the newrequirements in Article 690.31(A), you could raisethe height of a pole-mounted array; for groundmountedarrays, you must use fencing or othermeans to obstruct access to any exposed wiring.In the 2008 Code cycle, Article 690.31(A)concludes: “Where photovoltaic sourceand output circuits operating at maximumsystem voltages greater than 30 volts areinstalled in readily accessible locations, circuitconductors shall be installed in a raceway.”The NEC Handbook elaborates: “Most PVmodules do not have provisions for attachingraceways. These circuits may have to bemade ‘not readily accessible’ by the use ofphysical barriers such as wire screening.”Most integrators do not install moduleswith conduit ready junction boxes becausethese modules are limited in availability andtend to have low power characteristics.Raceway products designed to integratewith PV modules are not readily available.What was the intent behind 690.31(A)?Considering the substantial gap between theCode and the available equipment, how caninstallers comply with this new language?Whenever I give lectures or answerquestions about the NationalElectrical Code, I have a saying in theback of my mind: “There are many waysto interpret the Code—your way, my way,the engineer’s way and the inspector’sway.” It would be nice to add the “correctway” to that saying. The correct wayto interpret the Code, I think, is to fullyunderstand its intent.When that sentence from Article690.31(A) is distilled down to its parts, itbecomes clear that it is concerned aboutdc power conductors in a readily accessiblelocation being accessed or damagedby people or animals and causinga hazard. The main purpose of the NECis the practical safeguarding of personsand property from electrical hazards.One of the ways the Code accomplishesthis is by making electrical circuits notreadily accessible.The NEC definition of readily accessiblereads: “Capable of being reachedquickly for operation, renewal, or inspectionswithout requiring those to whomready access is requisite to climb over orremove obstacles or to resort to portableladders, and so forth.” Inspectors typicallyallow many options for making somethingnot readily accessible. One way isto place a physical barrier between theperson and the object, such as a lockeddoor, a panel cover requiring a tool toopen, a fence, or some other barrierrequiring a tool to remove. Another wayis to elevate the object out of arm’s reach;most inspectors will say that is about 8feet for a person of average height.If dc power conductors are not readilyaccessible, then they do not need tobe enclosed in a raceway. But I’m surethat making the conductors on theback of a ground-mounted array notreadily accessible has installers pullingtheir hair out. Some manufacturersare currently working on solutions thatintegrate the module, the support rackCourtesy meridiansolar.comand associated wiring intoa complete package thatmakes the conductors notreadily accessible.People often argue thattechnology changes happenso fast, the Code can onlyreact to the changes. Thismight be an example of theCode pushing new technologyto conform to the rules.Similarly, there is a proposalfor the 2011 NEC that couldrequire dc arc-fault circuitinterrupter protection on PVsystems. This is new technologythat might not be fullytested and listed, but couldbe required on installationsin the near future.Until more products areintroduced to the market thatconform to the last sentencein Article 690.31(A), theinstaller has several choices to build aCode compliant installation:• Find a module that allows araceway system to enclose theconductors;• Raise the array out of arm’s reach;• Install a barricade around the array;• Install a barricade around theconductors; or• Make the conductors in questionnot readily accessible.That last option might requireinstallers to communicate with theirlocal AHJ to discuss acceptable solutions.After all, the AHJ will be inspectingthe system for Code compliance, socommunication early in the process canalleviate headaches in the final stagesof the installation.—Brian Crise / NECA-IBEW ElectricalTraining Center / Portland, OR / nietc.org18 Solarpro | October/November 2009

Thinkinside thesmaller boxShown with inverter (sold separately) and optional remote, DC breakers, and backplate.The NEW Mini Magnum Panel (MMP)The new MMP is an inclusive, easy-to-install panel designed towork with one Magnum MS-AE, MS, RD or other non-Magnuminverter/charger.Features:• Small footprint: only 12.5”wide x 18” tall x 8” deep• Money-saving design:not only is the MMP lessexpensive, but it is pre-wiredfor fast installation, savinglabor costs• Easy access: front-mountedbreakers and remote (optional)• Choices: can be wired for 120VAC or 120/240 VAC output• Inclusive: works with non-Magnum inverter/chargers(stand-alone parts included)• Listed: ETL listed to UL1741and CSA C22.2 107-01Includes:• One DC breaker – 175A or 250A• One AC bypass breaker – 30Adual pole or 60A single pole• One AC input breaker – 30Adual pole or 60A single pole• 500A/50mv DC shunt• DC buss bars for batterypositive and negative• Din rail for optional DC minibreakers – will hold up tosix breakersTo learn more aboutthis new product visitwww.magnumenergy.comNow ShippingThe Powerful Difference

the Wire IndustryCurrentsKaye Evans-Lutterodt / solardecathlon.orgDOE Hosts FourthSolar Decathlon[Washington, DC] Twenty collegiate teams from the US, Canada, Germany and Spainare competing in the US Department of Energy’s fourth Solar Decathlon. Challenged todesign, build and operate the most livable and energy efficient solar powered home, theteams have spent more than a year in the design and build phase. Their entries are tobe transported to Washington, DC, in early October when a solar village will rise on theNational Mall. Solar Decathlon entries are judged in a total of 10 subjective and objectivecontests. For example, judges from the American Institute of Architecture evaluate lightingdesign and architectural aesthetics, while appliance efficiency and home comfortare measured and monitored by staff from the National Renewable Energy Laboratories.Past competitions required the solar powered homes to stand-alone, using battery storageand off-grid inverters. This year’s competition is net-metered, which will reduce thecost and complexity of the 800-square-foot structures. Final competition results will beannounced on October 16. Other than October 14, when they will be closed for testing,Solar Decathlon homes will be open to the public October 9–18.Solar Decathlon / US Department of Energy / solardecathlon.orgUS TreasuryCashPaymentsCan Replace30% ITC[Washington, DC] TheDepartment of the Treasuryand the Department of Energyannounced on July 9, 2009that approximately $3 billionin Recovery Act funds willsupport renewable energyproject development, includingsolar power projects.Application guidance forbusinesses is available online.Previously, businesses useda 30% federal tax credit toassist solar project financing,but the rate of new projectshas fallen as financing hasbecome harder to obtain.Under the new program,applicants agree to forgofuture tax credits in favor ofan immediate reimbursement.Applications for the Treasuryprogram are being acceptednow. Solar-related guidancefor the program is availableto SEIA members at seia.org.Department of Treasury /202.622.2000 /treas.gov/recovery/1603.shtml20 SolarPro | October/November 2009

Draker Releases Sentalis 800Monitoring System[Burlington, VT] Built around a rugged, reliable and accurate CampbellScientific CR 800 measurement and control system, the Sentalis 800from Draker Laboratories provides a simple, cost effective monitoringsolution for PV andwind turbine systems.Draker reportsthat the Sentalis800 will dramaticallyreduce monitoringcosts for smallto medium sizedsystems. A singleproduction meter,for example, providesperformancemonitoring forsystems up to 250 kW. All packages are delivered with prewired sensors.The Sentalis 800 will continue to collect data during temporary poweroutages, and its internal memory stores weeks of data to buffer againstany location-specific communication downtime.Draker Laboratories / 866.486.2717 / drakerlabs.comBP Solar Launches230 Wp EnduraModule in US[San Francisco, CA] BP Solar USA has introduceda low voltage, high current polycrystallinemodule line to the North AmericanPV marketplace. The 60-cell BP 3230N israted at 7.9 Imp at 29.2 Vmp. Power toleranceis +3%/−3%. The module’s tubular frameexceeds the extended IEC 61215 load test(5,400 Pa) in standard offset and end mount(short side) installations, and it includes agrooved channel thatholds M8 bolts captivewhen backside mountingsystems are employed.The potted junction boxincludes six embeddedSchottky bypass diodes forimproved heat managementand performance inpartial shade conditions.BP Solar USA / 866.277.6527 /bpsolar.usAURORA®Photovoltaic InvertersThe Installer-friendlysolution to all yoursolar requirements!▲ ▲ ▲ ▲ ▲Laptop-free configuration via front-panel mounted buttons.Two independent MPPT channels.True sine-wave outputs feature self-selecting voltage capabilities.Integrated RS485 port allows PC-based monitoring of up to 31 inverters.UL 1741/IEEE 1547 certified.PVI-6000PVI-3.0/3.6/4.21-800-678-9445 or (+1) 805-987-8741 (OUTSIDE U.S.)EMAIL: aesales-us@power-one.comwww.power-one.comsolarprofessional.com | SolarPro 21

You’ve come to expect a lot from Fronius.What’s next?It’s innovative and industry-leading as onlyFronius could bring you.But you’ll have to wait until Solar Power 2009 to find out more.Visit the Fronius booth – booth #2300 – at Solar Power International 2009 in Anaheim, California for the unveiling ofseveral new products that will revolutionize the way you think about solar.In the meantime, visit www.fronius-usa.com or call 810-220-4414 for more information on Fronius inverters, accessories,and innovative system monitoring and datalogging solutions.

Almost Timefor Anaheim By David Brearley and Joe SchwartzProducts, trends and technology to look for at the2009 Solar Power International ConferenceIf you have not already done so, it istime to make your reservations forNorth America’s largest solar businessto-businessconference and expo. SolarPower International (SPI) 2009 runs October27–29 in Anaheim, California. Manufacturersbuild their calendars around SPI,targeting new products for release at theevent. Think there is nothing new underthe sun? Think again.The sixth annual event was originally scheduled for SanJose. After unprecedented growth in 2008, however, eventorganizers—the Solar Electric Power Association (SEPA)and the Solar Energy Industries Association (SEIA)—relocatedSPI to the Anaheim Convention Center. The conferenceis expected to attract in excess of 750 vendors and 25,000attendees. Attendees can choose between more than 65breakout sessions, featuring 200-plus expert speakers. Comeearly and stay late; dozens of pre- and post-conference trainingworkshops are offered on Monday, October 26 and Friday,October 30. The new venue is also more family friendly,due to its proximity to Disneyland Park, which is hosting theofficial SPI party on Tuesday, October 27.Despite the rollercoaster market conditions, event organizersexpect this to be the largest conference ever. Thoughbusiness is down in general in 2009, resist the temptation toskip Anaheim. At the Intersolar North America conferenceheld in San Francisco earlier this year, few first-tier PV andinverter manufacturers were in evidence. However, overallattendance was up, with attendees lined up at the gates earlyeach morning. Despite the tendency for some big-name playersto stay away, the number of vendors actually increased111% over the previous year. Just as the soft market we areexperiencing this year was forecast, so is a rebound in 2010.Where and how this will happen, and what technologies andbusiness models will be favored, are all questions to answerin Anaheim.With that in mind, here are some highlights of interestingtechnologies and trends that you will want to investigatefor yourself.MODULESAfter years of consistent market growth and incrementalproduct improvement, evidence of a shakeup is everywhere.More seats, smaller table. Ironic, is it not? Just when demandcontracts for the first time in some 35 years, there are moremanufacturers than ever trying to bring solar modules tomarket. A quick survey of PV module vendors that attendedthe Intersolar event revealed some 100 manufacturers—fromAdvance Solar Photonics to Zytech—including 35 from China.Expect to see even more manufacturers at SPI.Buy America Act products. There is some confusion aroundwhat programs receiving Recovery Act funds have Buy AmericaAct provisions. Projects receiving a Treasury grant inplace of the 30% ITC do not. Other programs, like solar onfederal facilities, undoubtedly will. The good news is thatthe North American PV market in particular is expected tobe a bright spot for the global solar industry. While BP Solarannounced in March that it is phasing out module assemblyin Frederick, Maryland, the general trend runs counter.Expect to hear more talk than usual from international PVmanufacturers about opening US manufacturing or assemblyfacilities. In the meanwhile, the new SCHOTT Solar (us.schott.com) facility in Albuquerque, New Mexico, is online, and itsSCHOTT POLY line of modules—210, c o n t i n u e d o n p a g e 2 624 SolarPro | October/November 2009

© National Semiconductor Corporation, June 2009. National Semiconductor is a registered trademark and SolarMagic is a trademark of National Semiconductor Corporation. All rights reserved.Is your solar payback disappointing?Solar for the real world. www.solarmagic.comOptimize your system and maximize your return with SolarMagic power optimizers.SolarMagic technology enables each solar panel to produce maximum energy regardless of whether other panelsare under-performing due to real-world conditions such as shade and architectural obstructions. This advancedtechnology monitors and maximizes the energy harvest of each individual solar panel and reclaims morethan 50% of energy lost to real-world mismatch conditions.Real-world residential conditions like shade from trees, chimneys,and power lines, can significantly decrease solar power output.Real-world commercial building conditions like shade, vents, andair-conditioning units, can limit solar power output and ROI.SolarMagic power optimizers can recover up to 57% of theenergy lost to real-world conditions.To learn more and find an authorized dealer, visit www.solarmagic.com/paybackWINNER,Innovation Award—Photovoltaics

c-Si Solar PhotovoltaicsPower InternationalCourtesy solyndra.com217, 220 and 225 W—are listed and available now throughdistribution channels. SolarWorld, another first-tier modulemanufacturer with US based production, continues to rampup capacity output at its Hillsboro, Oregon, facility.Direct sales to integrators. While aleo solar North Americahas not yet announced plans for US module manufacturing,the wholly owned subsidiary of aleo solar AG (aleo-solar.com)has opened its US headquarters in Westminster, Colorado. TheGerman manufacturer of poly- and monocrystalline moduleshas indicated that its plans for coming to market in the USinclude direct sales to integrators. (Other companies are goingstill further, promising direct sales to end users.) This buyer’smarket will not last forever—certainly not to this extent—soconsider building relationships at SPI with manufacturers likealeo solar and others. Just be sure to do your homework andchoose your business partners wisely.Out-of-the-box thinking. Perhaps no PV manufacturerrepresents the spirit of innovation more than Solyndra(solyndra.com). The CIGS panel manufacturer thought rightout of the flat plate PV box when it developed its cylindricalmodule consisting of 150 series-connected CIGS cells. EachSolyndra panel consists of 40 parallel-connected cylindricalmodules. Two positive and two negative leads are includedfor making series and parallel connections in the field. InSolyndra CIGS cylindrical panelthe right application—commercial, low pitch, white membraneroof—the benefits from the ease of installation to theroof coverage and energy harvest are compelling. Becauseit is not a flat plate module, it does not have a sail effect,meaning that Solyndra panels mount on the roof via simplefeet that do not need to be attached or ballasted in place forthe system to achieve a 130 mph wind rating. More than oneindustry veteran has written the product off as a crackpotidea, but integrators familiar with the product respond thatit is just crazy enough that it might work. The US Departmentof Energy is a believer, having offered Solyndra a $535million loan guarantee earlier this year.INVERTERSLook for an unprecedented range of inverters on display inAnaheim, with options ranging from 190 W to 1 MW.Microinverters and ac modules. The smallest inverter generatedperhaps the biggest buzz at SPI 2008. Much of the excitementsurrounding Enphase Energy (enphaseenergy.com)was not about its microinverter per se, but rather about theEnlighten monitoring system. Using a powerline carrier totransmit and receive data over ac wiring, the Enphase dataacquisition system provides unprecedented transparency intoPV system operation. Some have dismissed microinverters as amere fad, pointing out that micros have been in developmentfor over a decade and have never gained traction or meaningfulinverter market share. Nonetheless, the current generation ofproduct may succeed where previous offerings failed.Today’s PV market is more mature, and microinvertersare successfully exploiting opportunities that few wouldhave imagined 5 years ago. At least two examples of thistrend will be on display in Anaheim. First, Akeena Solar(akeena.com) has successfully integrated Enphase microinverterswith its custom-framed, all-black modules thatSuntech manufacturers for the company. The result is theintegrated Andalay (andalaysolar.com) ac panel. Thoughnot a true ac module per NEC 690.2, it is nevertheless astep in that direction. The Andalay system simplifies arraysiting and system design; it offers a minimum parts count;and it provides a low-profile installation. This system couldbe particularly useful to contractors who are new to solar,for new construction projects or for companies that arestreamlining their operations.Similarly, the microinverter company Petra Solar(petrasolar.com) has announced an alliance with Suntechwith the goal of developing an ac module. Unlike startupGreenRay Solar (greenraysolar.com), which is developing anac module for the residential market, Petra Solar is successfullymarketing its SunWave product to utilities. In July thecompany announced that it had won a contract with New Jerseyutility PSE&G to provide 200,000 utility-pole attachablePV generation systems. If each SunWave solution consists ofa 200 W Suntech PV module and Petra Solar microinverter,the entire contract is good for some 40 MW of installed solarcapacity. Like Enphase, Petra Solar offers more than justmodule level inversion; it also provides granular monitoringas well as command and control. Each microinverter fromPetra Solar, for example, is capable of dispatching 100% reactivepower on demand into the power distribution network.The company is marketing this as a tool to provide utilitieswith greater ac system stability.Large scale inverters. For a variety of reasons—includingchanges to the solar investment tax credit, Recovery Act provisionsand impending carbon tax legislation—the developmentof utility scale solutions, in many c o n t i n u e d o n p a g e 2 826 SolarPro | October/November 2009

lueplaneta new inverter• Integrated and lockable AC/DC disconnects• Inverter separates easilyfrom switch housing• Field selectable grid voltages (208/240)• Field selectable positive ornegative grounding• Programmable LCD display• Plug and play monitoring• Standard RS485 interface• NEMA 3R enclosure• Convection cooled; highest reliability...from an old friendThrough direct interaction with installers and distributors across the country, KACO hasrealized the most pressing needs of experienced professionals to create the new KACO02xi inverter series. The 02xi inverter series is functional, sleek, and packed with featuresthat are exactly what you’ve been asking for.(866) 522-6765 • www.kaco-newenergy.comKACO offers solar training...call us today to find out more

c-Si Solar PhotovoltaicsPower InternationalCourtesy satcon.comcases by utilities themselves, is expected to account for muchof the installed PV capacity in coming years. For project developerswho do not wish to install megawatts of solar exclusivelyusing 200 W inverters, Anaheim will have much to offer.The Satcon (satcon.com) PowerGate Plus product line,for example, now includes a 1 MW inverter option, as wellas some 10 other power levels to choose from. According tothe company, a 1 MW inverter block is the largest practicalSatcon PowerGate Plus 1 MW invertersize for PV applications due to the unavoidable wire lossesassociated with six- to eight-acre arrays. The company alsooffers the Satcon Prism for utility class applications; thePrism integrates a pair of 500 kW inverters inside a weatherizedcontainer along with a medium voltage transformerand switchgear. Xantrex (xantrex.com) also released a lineof Solar Power Conversion Substations for large scale solarfarms in 2009.Fronius USA ( fronius.com) and Kaco new energy(kaco-newenergy.com), which have historically not offeredlarger 3-phase inverter solutions in North America, made itclear at Intersolar that they were working toward the releaseof 100 kW inverters. The Kacoproduct appears to be on trackfor release at SPI.Though SMA America (smaamerica.com)did not participatein Intersolar, the companyhosted an invitation-onlyevent in San Francisco the dayafter the conference wrapped.Attendees were treated to asneak peak at the Sunny Central500U, which SMA will undoubtedlyfeature in Anaheim.Tigo Energy Module Maximizer-ESString inverters. The biggest string inverter release at SPI inSan Diego last year was the IG Plus product line from Fronius.This year, look for Kaco new energy to feature its new02xi series of string inverters. Kaco is also participating inplans to bring an optimized two-stage power managementand inversion solution to market.DISTRIBUTED POWER MANAGEMENTTo a certain extent, the trend toward distributed powermanagement started with the release of the microinverter.One of the main benefits that module level inversion providesis the ability to optimize performance at its mostgranular level. This also requires locating an inverter on theback of every module, which undoubtedly fills some installerswith dread. Several companies are offering designers amiddle ground, two-stage solution: The first stage is moduleor string level MPPT; the second stage is inversion. Theresult is distributed, granular performance optimizationand centralized inversion.Module level MPPT. The poster child for module level maximumpower point tracking is SolarMagic (solarmagic.com)from National Semiconductor (national.com). National ismarketing its SolarMagic power optimizers, available now,for retrofit and new PV applications where the effects ofshading or module mismatch are of concern. Since manycell phones and laptops use National’s PowerWise circuitryproducts, perhaps SolarMagic power optimizers will soonbe built into PV modules. Its initial product, however, lacksmonitoring and datalogging capabilities and does not providevisibility into system performance. This limitation,along with SolarMagic’s MSRP of $199, may provide an openingfor competing products.Tigo Energy (tigoenergy.com), for example, is developinga similar product that it calls the Module Maximizer-ES.Tigo maximizers provide not only per-module MPPT but alsomodule-level monitoring and control. Though the ModuleMaximizer-ES is suitable for retrofit applications and workswith conventional inverters, Tigo is working with Kaco todevelop an inverter that is specifically designed to workwith its new product. This could resultin a more streamlined, less expensiveinverter, as MPPT circuits will no longerbe required. The Tigo product has anMSRP of $59.Both SolarEdge (solaredge.com) andXandex Solar (xandexsolar.com) are alsobringing module-level power optimizersto the US market.String level MPPT. The Satcon Solsticeuses a utility-class approach toprovide fine-grained energy harvesting.Instead of module c o n t i n u e d o n p a g e 3 0Courtesy tigoenergy.com28 SolarPro | October/November 2009

c-Si Solar PhotovoltaicsPower Internationallevel MPPT, string level MPPT is performed in Solstice smartcombiner boxes located throughout the array field. Thesesmart combiners monitor and log system performance, as wellas provide command and control throughout the array. Sincecombiners are already a service point in the PV system, from amaintenance point of view this new circuit architecture doesnot change things much. Also included in the combiner boxesare string level microconverters that boost PV source circuitvoltage close to 600 Vdc. This high dc voltage reduces wiresizes in the array, and the high dc bus voltage makes it possiblefor Satcon to employ a transformerless inverter architecture,meaning the Solstice inverter itself can be smallerand more efficient than conventional inverters. According toDr. Leo Casey at Satcon, the Solstice system promises 4% to5% improved yield for only pennies more per watt, which is acompelling value proposition for large scale PPA projects.COMBINERS AND RECOMBINERSA high profile PV array fire on a Target store in Bakersfield,California, this spring brought the need for dc disconnectsin the array field to the forefront of many integrators’ minds.One of the recommendations of the post-fire investigationreport was: “Provide dc disconnects at the output of all combinerboxes on the roof. The firefighters were looking for disconnectsthat were not there.” Segmenting disconnects atthe array enables first responders to better react during anemergency situation, and they also streamline ongoing systemmaintenance and troubleshooting efforts.Integrated disconnects. Three manufacturers develop andmarket combiner products that include an integrated dc disconnect.Blue Oak PV Products (blueoakpvproducts.com)was the first to market with a listed line of five combinermodels that include a load break rated disconnect. AMtecSolar (amtecsolar.com) and SolarBOS (solarbos.com) havealso introduced disconnectingcombiner products. The BlueOak and SolarBOS disconnectingcombiners are listed to 600Vdc, while the AMtec productsare pushing the voltage ceilingwith 1,000 Vdc ratings.Recombiners and monitoring.Additional combiner innovationwill be on display at SPI2009. AMtec will be launchingits new Equinox series recombiners,available in three sizesfrom 4 to 20 circuits with 750 Ato 2,000 A ratings. All Equinoxrecombiners will be availablewith or without monitoringcapabilities. Somewhat of a SolarBOS Disconnect Combinerdisconnect previously existed between PV equipmentand third-party monitoring solutions that left installersscratching their heads while they waited on their cell fortechnical support. To ease their pain, SolarBOS has teamedup with new-to-the-field DECK Monitoring (deckmonitoring.com)to develop a standardized, seamless string- andsystem-level monitoring solution.RACKINGPhotovoltaic racking system manufacturers have been developinga myriad of approaches to reduce component count,speed installation, ensure leak-free attachments in pitchedroof mount applications and ultimately drive down installedcost per watt. Quick Mount PV (quickmountpv.com) and S-5!(s-5.com) will be exhibiting their expanding lines of flashingand attachment systems at SPI 2009; Unirac (unirac.com)will show its recently introduced CLICKSYS product for flushmount applications. Among the dozens of racking manufacturersthat will be sporting product innovations at the event,put the following two on your Do Not Miss list.Simple and adaptable. Only a 0.5-inch wrench is required forassembling AEE Solar’s (aeesolar.com) SnapNrack PV mountingsystem. The rail based mount starts on the roof with eitherflashed L-foot or flashed post attachment options. The latterallows for slight tilting or an increased standoff from the roofdeck. Standoff adjustability allows you to straighten out thearray plane over irregular roof surfaces.The system’s thread inserts (used to secure top-downmounting bolts, rail splices and post or L-foot attachments)can be installed along the entire rail section, saving you alot of back and forth work on the roof. Mid-clips are 0.5-inch wide to keep layout math simple. The rack’s rail profileincludes a wire management channel for securing and coveringmodule leads. If you are not working on pitched roofprojects, SnapNrack’s postscan also be used in nonballastedlow-slope roofapplications. A pipe-to-railoption makes the systemcompatible with groundmounted installations.Reenvisioning the moduleframe. We recently traveledto San Rafael, California, toreview a new, no-rail mountingsystem that was pitchedas “the MC connector ofPV racking development.”We were not disappointed.Courtesy solarbos.comIn Anaheim inventor JackWest and cofounder DanielFlanigan continued on page 3230 SolarPro | October/November 2009

Visit us at Solar PowerInternational, booth 501.www.us.schottsolar.comSunny Days Are Here.SCHOTT Solar modules are producedwith pride in Albuquerque,NM from foreign and domesticcomponents and qualify as ado mestic end product under:the Buy America Act, the TradeAgreement Act, and the Amer icanRecovery and Reinvestment Act.Tested at twice the internationalstandard, SCHOTT Solar modulesare gua ranteed to perform at orbetter than specification. Becausethe forecast calls for solar, whateverthe future holds.

c-Si Solar PhotovoltaicsPower Internationalwill be launching their patented mounting system, designedand manufactured by the newly formed Zep Solar (zepsolar.com) in partnership with groSolar.When you first see the system, your likely reaction willbe “Really? No rails?” Zep Solar took a forward-lookingapproach: customize the module frames to directly acceptthe racking components and engineer the composite systemto support the design loads—without increasing the dimensionsof the frame. Initially, Zep Solar will be launching itsproduct for use with Evergreen laminates.The frames are designed with tapered channels (ZepGrooves) that accept the core components of the rackingsystem—the Interlock and the Leveling foot, each containingthe Zep, a device that locks into the groove and groundsthe module frame (auto-grounding) using a specialty tool.With the first row of modules in place, each successive moduledrops in at a 15° angle and lowers into position with apivot-lock action.So what are the advantages? Reduced materials, partscount and shipping costs (no rails); auto-grounding of allmodule frames; and extremely rapid installation. You caneven straighten the plane of the array from the top with adrill-driven adjustment of the Leveling Foot. Zep Solar’sobvious challenge will be building relationships with modulemanufacturers that are willing to customize frames withZep Grooves. However, this general degree of customizationhas been accomplished before and variants on moduleframes are becoming more common. Zep Solar plans on fullcommercialization of its innovative product in Q1 2010, butmake sure to check it out at the groSolar booth at SPI 2009.will enable system designers to lay an array out virtually,identify individual strings, import SunEye readings from thefield and then, with the push of a button, generate detailedenergy harvest estimates. Early reports are that the softwareinterface is slick and user friendly, and PVDesigner will likelywin many fans in the industry.On the back end of projects is commissioning and acceptance,which are not only time consuming—preparing formsand templates, performing tests and documenting theresults—but also warrant a third party seal of approval. Solmetricbelieves that its PV System Performance Analyzer isthe solution. The PV analyzer is basically a portable I-V curvetracer that includes a remote control, remote irradiance andcell temperature sensors, and PC software. Its purpose is tomeasure, model and log system performance at the stringlevel. The device models performance by comparing stringCourtesy solmetric.comSolmetric PVDesignerCourtesy zepsolar.comZep Solar’s Zep MountDESIGN AND COMMISSIONINGYou are probably familiar with the SunEye shade measurementtool from Solmetric (solmetric.com). However, youmay not be familiar with the suite of products that Solmetricis developing to improve PV system design and commissioning.The PVDesigner software program, for example,level I-V curve measurements with a Sandia model. It iscapable of identifying a variety of manufacturing or installationdefects. The device is used with a PC, preferably a ruggedizedone, and as the technician gathers measurements inthe field, the PV analyzer builds a database that can be usedlater to inform acceptance documentation.Look for product innovations and more at Solar Power International2009 in Anaheim, California, October 27–29, 2009.g CONTACTDavid Brearley / SolarPro magazine / Ashland, OR /david.brearley@solarprofessional.com / solarprofessional.comJoe Schwartz / SolarPro magazine / Ashland, OR /joe.schwartz@solarprofessional.com / solarprofessional.com32 SolarPro | October/November 2009

PV System

CommissioningBy Blake GleasonPV is simple: Turn it on; have sun; make power.Commissioning may seem like an unnecessarilytime-consuming and complex exercise, but it is acritical part of a well-installed system.shawnschreiner.comUnderstanding and paying attention to PVcommissioning is important to the industry.If the PV industry is to continue to expandand become a significant part of the USenergy portfolio, short- and long-term systemperformance is critical to maintainingpublic confidence and goodwill. Already,many interested parties are making concerted efforts tomaintain the quality control of installed systems. PowerPurchase Agreement (PPA) providers, for example, mustprotect their investments; manufacturers want to see thePV market grow; and legislators and rebate administratorsneed to encourage responsible industry growth. Integrators,who play such a large role in the story, must do their partto ensure the safety, quality and performance of installedPV systems.Commissioning is a way to formalize quality control ofinstalled PV systems. The process ensures that systems aresafe and high performing. It encourages integrators to beresponsible for their installations and facilitates projectcloseout and prompt payment. Successful commissioningleads to satisfied installers, employers and system owners.Satisfied customers become repeat customers and lead tonew clients. Seen in this light, commissioning is essential tothe growth of the PV industry and to the overarching goal ofinstalling more renewable energy systems.Think this is an overstatement? Consider what commissioningprevents. It protects against fires, shocks and injury.It keeps customers happy and minimizes callbacks. It ensuresthat a lot of silicon, aluminum, glass, steel, copper, dollars andeffort are not wasted on nonperforming or underperformingsystems. Commissioning guards against a lack of public confidencein PV and renewable energy technologies.This article covers the commissioning of both residentialand commercial scale grid-tied PV systems in detail.Although it does not specifically address off-grid, batterybackupor vehicle PV systems, many of the same principlesapply. Similarly, while large utility scale PV systems are notspecifically exemplified, the commercial scale proceduresare easily scalable.The building commissioning processThe commissioning process is typically applied to entirebuildings. To set a framework for PV commissioning, itis useful to examine the total building commissioningprocess. The Building Commissioning Association (BCA)defines commissioning in its sample specification as:“a quality-oriented process for achieving, verifying anddocumenting that the performance of facilities, systemsand assemblies meet defined objectives and criteria. Thecommissioning process begins at project inception (duringthe pre-design phase) and continues through the life ofthe facility. The commissioning process includes specifictasks to be conducted during each phase in order to verifythat design, construction and training meet the owner’sproject requirements.”solarprofessional.com | SolarPro 35

PV System CommissioningFurther, the BCA outlines the basic tasks of commissioning:• Verify that applicable equipment and systems areinstalled according to the contract documents,manufacturer’s recommendations and industryaccepted minimum standards.• Verify that installing contractors perform adequateoperation checkout.• Verify and document proper performance ofequipment and systems.• Verify that the operations and maintenance (O&M)documentation left on-site is complete.• Verify that the owner’s operating personnel areadequately trained.• Establish performance benchmarks.• Complete any required acceptance documentation.• Train the system owner on basic system operation.Safety in commissioningYou should take the same safety precautions that youuse during PV installation when commissioning the system.Fall protection, ladder safety, electrical safety, personalprotective equipment and common sense are allrequired. When commissioning personnel are not partof the installation crew, they are not familiar with thehazards on a particular job site. They may not be familiarwith best practice construction safety continued on page 38commissioning PV SYSTEMSTypically, system owners have specificgoals in mind for their PV system. Thesemight include reducing electric billsby a certain percentage, maximizingthe power output from available roofspace or maximizing return on their PVinvestment. These goals are known asthe owner’s project requirements. The PVsystem designers then devise a strategyto meet these requirements. This strategy,including documents describingthe intended system components andcalculated expected performance output,is called the basis of design, whichshould help guide the PV commissioningprocess.At the most basic level, commissioningensures that the owner’s requirementshave been met. Most of the PVsystem commissioning will occur afterinstallation is complete and before projectcloseout. It should include the followingelements:• Verify that the installation iscomplete.• Verify that the installation issafe.• Verify that the installation isaesthetically acceptable.• Verify that all components ofthe installation are robust andpermanent.• Document as-built conditions.• Verify system performance.• Verify proper system operation.Quality assurance Commissioning is a process that starts during predesign andproceeds through PV system acceptance. Far more than an inverter start-upsequence, commissioning documents the as-built condition of the system—like thisinstallation by Sun Light & Power in Berkeley, CA—and ensures that the installation issafe, durable and performing properly.shawnschreiner.com36 SolarPro | October/November 2009

PV System Commissioningprocedures. In that case, a qualified installer should be presentand responsible for maintaining safe conditions duringcommissioning. All equipment inspections should be madewith both utility and solar electrical sources switched offand locked out.After inspections, the equipment is energized at commissioning,often for the first time. Proper testing and plannedsequencing will ensure that neither equipment nor peopleare subject to destructive voltage or current. Be alert. If somethingseems wrong or if unexpected phenomena result whenenergizing equipment—such as pops, bangs, smoke or suddendarkness—do not rush to try to “fix” the problem. Slowdown; determine the cause; make sure no hazard is present;and then determine the best course of action. If a ground faultis indicated or suspected, assume that all conductive surfacesin the system present a shock hazard until testing determinesotherwise. (See “PV System Ground Faults,” August/September2009, SolarPro magazine for detailed information onlocating and troubleshooting ground faults.)Commissioning ProcessEspecially for larger projects, during the design phase commissioningshould be incorporated into the specificationsand bid documents. Include required documentation, checklists,testing procedures, expected performance and basis ofdesign. It is also important to specify requirements for thecommissioning timeline and give guidance on what personor entity will be responsible for the commissioning.Timeline. Commissioning should be considered throughoutthe course of a PV installation project. It should beplanned for during the design phase, built into the systemcost, actively carried out at the end of construction andrepeated as desired after project completion. However,most of the commissioning work will occur just after the PVinstallation is complete and the system is ready to be turnedon for the first time.This initial startup is often called commissioning thesystem. Ideally, this commissioning event occurs after allpermits are signed off; both permanent power and Internetare established at the site; the utility has given permissionto operate the system; and the monitoring system, if applicable,is operational. If one or more of these milestones isdelayed, you may want to start up and test the system regardless.Final acceptance of the system may still be contingenton passing subsequent milestones, but you can verify systemperformance in the meantime. One continued on page 40Recommissioning andRetro-commissioning ofExisting SystemsRecommissioning. Repeating the commissioning of a systemthat was previously commissioned is called recommissioning.Usually, recommissioning should be the last step in anysubstantial maintenance project, such as after replacing majorcomponents, especially inverters; after adding additional modules;after a non–self-clearing alarm is diagnosed and repaired,such as a ground fault; and as part of a system checkup orregular annual maintenance visit.In addition, if the original commissioning was performedduring less than optimal seasonal conditions, like shadingor extended poor weather, a recommissioning event may becalled for during better conditions or in the summer. Recommissioningresults should be closely compared to those fromthe original commissioning. If the results are inconsistent(after accounting for shading or other changes), the systemintegrator should track down the source of the inconsistencies.Recommissioning performance results should also becompared to updated expected performance numbers anddiscrepancies addressed.Retro-commissioning. For PV systems that were notproperly commissioned in the first place, all hope is not lost.Retro-commissioning can be performed at any point in thesystem’s lifetime. Although commissioning is a good idea forany system and is better done late than never, the additionalexpense of retro-commissioning may be best justifiedwhenever there is a significant concern that the system isunderperforming. Several indications of possible underperformanceinclude:• Monitoring system reports faults, alarms or lowperformance.• Utility bills are higher than expected, after taking intoaccount any new loads.• One inverter shows significantly less accumulatedkWh than others, even though they all have the samesize arrays and no difference in shading.• Total accumulated kWh, read from the inverter, issignificantly less than predicted for the relevanttime period. {38 SolarPro | October/November 2009

Are you ready to drop in?PATENT PENDINGDrop-in Mounting Systems by Zep SolarWorld’s first auto-grounding, drop-inpivot-locking, quarter-turnrapid-leveling, hyper-bondedinterlocking, light-weightrail-free, module-couplingsystem.Live Demos at SPI 2009 Booth 309www.zepsolar.com

PV System Commissioningexception to this timeline is for systemsthat have a “burn in” period, such as thinfilm amorphous silicon systems. Thesesystems will experience a significant, butexpected, drop in production over thefirst few weeks and months of operation.Therefore, performance measurementsmade at initial system startup will be artificiallyhigh. Recommissioning is requiredafter this burn-in period.Be sure to schedule the commissioningas soon as possible after PV systemconstruction is complete, but within asuitable window of weather. It does notmake sense, for example, to commissionwhen there is irradiance of less than400 W/m 2 in the array plane. Not onlymust the weather be good, but the timeof day must also be appropriate.Especially on small projects, thetendency is to try to commission thesystem at the end of the last day ofinstallation. This strategy is efficientbut not effective. Often, the sun is toolow in the sky to provide sufficient irradiancefor proper performance verification.Shading is also more likely atthe end of the day, and any shade onthe array makes performance verificationdifficult. Finally, commissioningdemands focus, clear thinking andsufficient time. If the end of the day isnear, the crew may be cold, hot, hungry,thirsty or just ready to go home. None of these conditions arelikely to produce accurate commissioning results. It is betterto clean up, go home and come back another day when thesun is out and minds are fresh.Who does it? For commissioning to be most effective, thecommissioning party should not be inclined towards a cursoryprocess with a guaranteed positive outcome. The contractorwho installed the system will usually have this bias.Ideally, the commissioning party should represent the systemowner, not the installer, and should be able to act completelyin the owner’s interest without conflict. For large systems,the owner should contract with an outside commissioningspecialist to oversee the commissioning process.If the scope of the project is not sufficient to bring in anoutside specialist and a direct representative of the owneris not available, commissioning should be performed by anobjective party under the original system integration contract.For small commercial projects, for example, an engineeror system designer might be the best choice for the job.Torque settings Before commissioning is complete, verify all torque settings. Theauthor is shown here with a torque wrench verifying the compression of groundeddc current carrying conductors inside a Satcon inverter.Even though the engineer works for the integrator, he or sheis at least one level removed from the physical project.At a bare minimum, a person with sufficient knowledgeabout PV in general and the system being commissioned inparticular must undertake commissioning. This is true even forsmall residential projects, where the best person to commissionmight be the crew leader who was in charge of the installation.As someone with a supervisory role, the crew leader can delegateany corrective tasks and focus on effective commissioning,leaving behind a system to be proud of. Regardless of the level ofobjectivity, whoever carries out the commissioning must havethe proper tools and sufficient training.Documentation. The commissioning agent must start withall of the available system documentation. Before undertakingcommissioning, relevant documentation such as thefollowing must be on hand: drawings, ideally as-built; cutsheets for modules and inverters; specifications, especiallyas they pertain to commissioning; special requirements orforms for rebate programs or other incentives; and equipmentmanuals. continued on page 42shawnschreiner.com40 SolarPro | October/November 2009

PV System CommissioningThe commissioning agent must also understand whatdeliverables are required at the end of the process. For amunicipal or federal PV project, for example, the deliverablesare often extensive and detailed in the bid package.For a residential project, the commissioning documentationmay be part of a post-installation punch list that remains inthe customer file for internal use.Commissioning TasksFor a small PV system, commissioning might mean thatthe installer takes a step back, looks over the installation,tests voltage at a few points, watches as everything turns onsuccessfully and verifies system performance. At the otherextreme, for a large PV plant there might be a dedicatedcommissioning team with a multi-day, multi-faceted commissioningagenda, including follow-up activities and writtenreports. Whatever the scale, and whoever does the commissioning,the basic tasks and goals of the process remainthe same.Verify that the installation is complete. Are all componentspermanently installed? Is everything wired completely? Permanentutility power should be connected at the site. Inaddition, if Web based monitoring is being used, the Internetconnection should be operational. Examine the most recentinstallation punch list to make sure all items are complete.Verify that the installation is safe. Has the permit beensigned off ? Are the mechanical and structural systems adequateand built according to plan? Has any required waterproofingbeen completed satisfactorily? Has the electricaldesign been adapted properly?A few common problem areas are worth checking:elements and the environment it will be subjected to for thedesign life of the system, usually 30-plus years for PV systems.Fasteners should be stainless steel, and steel rack elementsshould be hot-dipped galvanized or better. Dissimilarmetals must be isolated to avoid galvanic corrosion. Wiringand raceways must be suitable for their location. Sunlightresistant wire is required under arrays, for example, andelectrical metallic tubing (EMT), intermediate metal conduit(IMC) or rigid metal conduit (RMC) is required on theroof. Make sure that NEC required labeling is present andthat it is made of appropriate materials, such as engravedmetal or plastic.Document as-built conditions. During the visual systemreview, note anything out of the ordinary. continued on page 44Photo document In addition to approving installation practices,like proper conduit support spacing and the tightnessof conduit fittings, the commissioning agent should documentthe installation’s as-built condition with many photos.• Make sure working clearances are maintained.• Verify that all metallic surfaces that might becomeenergized are grounded.• Ensure that wire and conduit sizes installed in thefield are as shown on the plans.Verify that the installation is aesthetically acceptable. Checkto see that the PV array is only as visible as it was designed tobe. Verify that module lines are straight and parallel to rooffeatures, especially where visible from the ground or hightraffic areas. Is all other equipment installed plumb, leveland with good workmanship?Are any required aesthetic treatments complete? If thiswas part of the contract, for example, inspect whether conduitsystems and disconnects are painted to match the walls.Ensure that PV array skirts, where required, are installedand satisfactory. Check that inverter fences or enclosuresare built as designed.Verify that the installation is robust and permanent. Ensurethat all outdoor equipment is designed to withstand theshawnschreiner.com42 SolarPro | October/November 2009

Bright Thinking in SolarR

PV System CommissioningEach questionable item should be written down and photographed,with the photo location marked on a roof planor other appropriate drawing. Take pictures of all arrays,ideally from at least two angles. Also take pictures of conduitruns, combiner boxes, disconnects, inverters and theinterconnection.Verify that the module layout matches the approved roofplan drawing. Note any discrepancies on the drawing. Verifythat the module string layout is as shown on the as-builtstring diagram, including consistency of wire and stringnumbering. Accurate string diagrams are extremely helpfulfor future maintenance and troubleshooting. For smallersystems, if a string diagram does not exist, identify the stringlocations and document them on the roof plan. For large systemsmissing a string layout, identify this as an action itemfor the integrator.Document the model number and quantity of the modules,inverters, combiner boxes, disconnects and monitoringsystem.Expected PerformanceProbably the most difficult and the most important aspectof commissioning a PV system is evaluating whether it isperforming as well as it should be. First, the expected performanceneeds to be determined. Then, the actual performanceneeds to be measured.To determine the expected performanceof the PV system, referto the basis of design. Assumingthat the system was sized properlyin the design phase, it should meetthe owner’s requirements for energyproduction. Based on the equipmentspecified, estimate the monthly,annual and lifetime energy outputof the system.Many software packages and Webbased calculators can simplify thistask. For example, you can use thefree PVWATTS Web based calculatorto get a very quick energy harvestestimate by inputting the peak dcCell temperature An infrared thermometeris often the easiest toolfor measuring cell temperature. Forperformance verification testing,average one set of cell temperaturemeasurements at the beginning andanother at the end of the performancemeasurement period.shawnschreiner.comrating of the system, the system location and the array orientation;monthly and annual kWh performance estimates aregiven as an output. The California Solar Initiative (CSI) rebatecalculators are also available to the general public, althoughthey are of interest primarily to California utility customers.For example, the CSI Expected Performance-Based Buydown(EPBB) calculator (see Resources) allows for the input ofspecific module and inverter combinations, monthly shadingdata, as well as information about the site location andarray orientation. It does not, however, allow changing otherassumptions such as module mismatch, wire losses and systemavailability. EPBB uses PVWATTS for its back end.Many integrators, PPA providers and third-party softwaredevelopers provide performance calculators. Some productsavailable for purchase, like Clean Power Finance and Quick-Quotes from Clean Power Research, include updated electricalrate schedules and other information not only to estimatePV production but also to provide detailed financialanalyses. Fortunately, for commissioning purposes, all thatyou need are the power and energy output of the PV system.Since all of the energy calculators are based on averagehistorical weather data, a PV system should not be expectedto produce exactly the amount predicted by the energy calculatorin a given day, week or month. The longer the interval,the better the actual performance should match the predictedperformance. While thereis significant variation in weathereven from year to year, certainlyafter 5 or 10 years the system’s totalaccumulated energy productionshould match the predicted output.Unfortunately, 10 years is too longto wait to make sure the system isworking as intended.At initial system commissioning,very little historical productiondata is available. Therefore, thesingle best metric to verify systemperformance in the short term isthe instantaneous power output ofthe system. The following processis one way to estimate the expectedvalue of the system power output atany moment.1. Determine the peak dc powerrating of the system. This value willbe the sum of the power outputs ofideal individual modules at STC.Obtaining this number is straightforward,because it is the product ofthe nameplate module rating (P STC)and the total quantity of modules.44 SolarPro | October/November 2009

2. Calculate the irradiance factor,K I. First, use a pyranometer to measurethe actual irradiance in wattsper square meter. This measurementshould be taken in the same plane asthe modules, with the same azimuthand tilt angle. Divide the measuredirradiance by the STC irradiance(1000 W/m 2 ) to obtain the irradiancefactor.3. Calculate the module cell temperaturefactor, K T. Measure the cell temperatureT Cof the modules in Celsiususing a thermocouple, thermistoror infrared (IR) thermometer. Findthe module temperature coefficientof power, C T, from the module datasheet or module manufacturer. Thiscoefficient is typically in the range of−0.003/°C to −0.005/°C for crystallinesilicon modules. Then, calculate K Tas follows:K T= 1 + (C T× (T C− T STC))SProbably the mostdifficult and the mostimportant aspectof commissioning aPV system is evaluatingwhether it is performingas well as it should be.First, the expectedperformance needs tobe determined. Then,the actual performanceneeds to be measured.The cell temperature factor usually represents a reductionin power from the STC rating of a module due to celloperating temperature well above STC temperature (25°C).4. Determine the system derating factor, K S. This factor is aproduct of all of the system efficiencies and miscellaneoussubfactors, including: module mismatch, inverter efficiency,module soiling, module nameplate tolerance, wiring losses,shading, system availability, tracking efficiency and age.PVWATTS describes many of these factors and providesdefault values. For instantaneous power measurement atsystem commissioning, the following values are typical,although module-dependent factors can vary substantiallybetween manufacturers:Module mismatch = 0.97 This is representative unless thesystem uses individual module power point tracking devices,such as microinverters or dc-to-dc power optimizationdevices, in which case the mismatch is eliminated and thissubfactor becomes 1.0.Inverter efficiency = 0.96 A value in the 0.94 to 0.96 range istypical for most modern high efficiency grid-tied inverters.Module soiling = 1.0 Assuming the system being commissionedis brand-new, there is no need to derate for soiling.Module nameplate tolerance = 0.99 It is reasonable to use0.99 or better for most high-quality module manufacturers.Wiring losses = 0.98 These include dc wiring losses andconnection losses up to the inverter, where instantaneouspower output measurements are usually made.Shading = 1.0 If the array is shadedat all, proper verification of performanceoutput is very difficult.Make sure it is not shaded duringcommissioning.System availability = 1.0 Duringcommissioning there is no need toderate for availability; the systemmust be operating (available) whentaking power measurements.Tracking efficiency = 1.0 Trackersshould be in perfect working order duringcommissioning. Since irradiancevalues are taken in the module plane,this factor is irrelevant regardless.Age = 1.0 A brand-new systemhas yet to experience any age relateddegradation.Typically, the resulting systemderating factor, the product of allsystem derating subfactors, is approximatelyK S= 0.90.5. Calculate expected system performance,P E. Each of the factorsabove—irradiance, cell temperatureand system efficiency—adjusts the expected output ofthe system relative to the controlled STC power rating.The overall expected power output from the combinationof these calculated and measured factors is determinedas follows:P E= P STC× K I× K T× K SIt is important to maintain perspective on the calculationof this expected power output. For a given set of modules,the irradiance is by far the factor with the most variation. Itis imperative to get reliable irradiance measurements to calculateK I; otherwise, the power estimate will have so muchuncertainty that all of the other factors become meaningless.Assuming that shading is avoided, the system deratingfactor, K S, usually varies by a few percentage points, at most.The cell temperature factor, K T, is not very sensitive to moderatechanges in temperature. Assuming a module with a temperaturecoefficient of power C T= −0.004/°C, for example, arelatively large cell temperature change of 10°C changes thecell temperature factor by only about 4%. The net effect onthe power estimate is only a few percentage points if the IRthermometer used to take cell temperature readings is nothighly accurate. The same is true if the cells measured happento be abnormally high or low by a few degrees, or evenif the cell temperature is estimated based on a certain riseabove ambient temperature.solarprofessional.com | SolarPro 45

PV System CommissioningThe irradiance reading in the module plane, however, caneasily vary from 400 W/m 2 to 1200 W/m 2 . From the 800 W/m 2nominal terrestrial environment base value, irradiance inthe plane of the array might change 50% in either direction.The effect of this range of irradiance on the net predictedpower output is also +/− 50%. Clearly, it would be unacceptableto look up at the sky and guess “bright,” “overcast”or “hazy,” rather than taking an accurate in-plane irradiancemeasurement. On a residential system with as few asthree paralleled strings, an entire string could be disconnectedand the commissioning test might not catch it if thein-plane irradiance is not measured with precision.PERFORMANCE MEASUREMENTSThe second half of performance verification is comparingthe expected power output to the measured power output.After you have verified that all of the specified equipmentwas installed, you can measure and document the performanceof that equipment and compare it to the expectedvalues. Personal protective equipment is mandatory. Severaltests are mandatory prior to inverter start-up. After start-up,you can capture measured power output and compare it tothe expected performance.Megger test each homerun. Homerun wiring should be testedwith a megohm-meter before modules are connected. In fact,depending on the type of racking and accessibility under themodules, often homerun wiring should be Megger testedbefore the modules are installed. If problems are found, thehomerun wiring is completely accessible for examinationand replacement. Also, after all of the homerun wiring checksout, both module-to-module connections and module-tohomerunconnections can be made as the modules are placed,as long as the inverter ends of the homeruns are safely terminatedand locked out. Even though Megger testing is typicallycarried out before the PV installation is complete and full commissioningcan occur, the test results should be documented asthey are obtained to avoid the need to repeat testing later.Measure Voc of each string. Open-circuit voltage can bemeasured only while the strings are independent of eachother and before they are combined. For small string inverters,this may mean measuring Voc on the line side of the dcdisconnect, with the dc disconnect open. For larger inverters,it likely means measuring Voc on the line side of thefuseholders in the combiner boxes, with the fuses removed.Once the combiner box fuses are inserted or the dc disconnectis closed in a system with no combiner box, all of thestrings are combined in parallel. Therefore, they will all measurethe same Voc, which is misleading when trying to verifyindividual strings. Verifying individual string Voc measurementsis the quickest way to ensure that continued on page 48Inverter start-up The sequence of steps required prior to inverterstart-up includes line-to-line, line-to-neutral and line-to-ground measurementsat the ac disconnect.Voltage measurements As evidenced by thisopen-circuit voltage measurement, the samepersonal protective equipment required forbuilding the PV system is required duringsystem commissioning.shawnschreiner.com (2)46 SolarPro | October/November 2009

PV System Commissioningall strings have the same number of modules and the correctpolarity. After this is verified, replace the series fuses andclose the fuseholders.Inverter startup sequence. After you have completed all thevisual inspections and confirmed the dc open-circuit stringvoltages, the system can be started up. Always follow theinverter manufacturer’s directions for initial startup. Typically,the steps will include the following:• Verify all connections.• Verify correct ac voltage at the acdisconnect.• Verify correct dc voltage and polarity atthe dc disconnect(s).• Close the ac disconnect.• Verify correct ac voltage at the inverterac terminals.• Close the dc disconnect(s).• Verify dc voltage and polarity at theinverter dc terminals.• If applicable, switch the inverter “ON.”• Wait for the inverter to step throughits internal startup sequence.• Once the inverter is running, wait about15 minutes for internal temperaturesand power point tracking to stabilize.Measure Imp for each string. Before paying much attentionto the total inverter output, verify that each string is producingapproximately the same amount of current. At the combinerbox or another accessible location, use a dc clamp meter tomeasure the current in the ungrounded source circuit conductorof each string. If weather conditions are consistentduring the testing and all strings are oriented with the sameazimuth and tilt angle, the measured current values shouldbe identical, or at least within about 0.1 A of each other. Forsystems with individual module monitoring, verify that allmodules are producing the same power levels.If one string has no current at all, check again to make sureboth homeruns and all module leads are plugged in. If onestring has lower current than the others, double-check to makesure that string is not partially shaded either by a distant tree,a nearby person or the commissioning agent’s notebook restingon one of its modules. If no shading is present, measure thecurrent on the grounded dc string conductor. If the current isdifferent on the grounded conductor and the ungrounded conductorof the same string, a ground fault is likely carrying thedifference in current. For larger central inverters, the groundfault current from a fraction of one string may not be enough totrip the detection circuitry or blow the fuse.Measure ac power output. If measured current on all stringschecks out, it is time to verify the inverter ac power output.Pyranometer readings For best results, measure irradianceand inverter ac output simultaneously. This is most easilyaccomplished with two people. Alternatively, you can set thepyranometer up on a tripod near the inverter and align it tomatch the azimuth and tilt angle of the modules.Using a clamp meter for current and a multi-meter for voltage,verify that the voltage, current and power displayed on theinverter match the measured values. Ideally, an independentpower meter is used for this purpose, since it can also verifypower factor and other power quality components. Once youhave verified the inverter’s internal meter and display, you canuse the power readings displayed on the inverter for all subsequentpower measurements and reporting.Performance VerificationAfter completing all of the commissioning tasks and performancemeasurements as described, it is time to measurepower performance and compare this to predicted values.Only three measurements are necessary: cell temperature,irradiance and inverter ac output.Of the three, cell temperature is the most stable, andac output is less sensitive to changes in temperature thanchanges in irradiance. Take one set of cell temperature measurementsat the beginning and another at the end of theshawnschreiner.com48 SolarPro | October/November 2009

performance measurement period. Theeasiest tool to use for this purpose is anIR thermometer. Use this instrument tomeasure a few cell temperatures in differentplaces on a module and in a varietyof locations throughout the array. Writedown the average cell temperature indegrees Celsius.Irradiance and inverter ac output mustbe measured simultaneously. Even on a relativelyclear day, high clouds or haze canquickly change irradiance. Remember tolook up at the sky periodically during testing.In one case, I was so focused on jumpingback and forth between reading theinverter displays and getting the pyranometer lined up withthe modules, I was surprised when I looked at the measurementsI had written down over a period of about 2 minutes.One irradiance value was much higher than the other two. Atfirst, I thought I must have written it down wrong or held thepyranometer at the wrong angle—pointing directly at the sun,for example—but then I noticed that the inverter output wasalso much higher. Finally, I looked up at the sky and noticedOur system DOES NOT search forthe sun, it FOLLOWS the arc of thesun, returns at midnight, and adjustselevation for the changing seasons.SIt is imperative to getreliable irradiancethat what had been a completelyclear sky now had a couple of hardedgedcumulous clouds. I had justmeasured about a 10% increase inirradiance and production fromthe elusive edge-of-cloud effect.With a full monitoring systemor portable datalogger, 15minutes’ worth of averaged irradianceand ac output provide anexcellent simultaneous reading.However, even with a simple $150pyranometer and the inverter display,you can obtain good resultswith the following method:Find a good location to place the pyranometer so thatit has exactly the same azimuth and tilt angle as the modules.Ideally, the instrument has a square edge or bracketand can be clamped or held in place on the corner of a moduleto ensure alignment. Make sure the pyranometer doesnot shade the modules. Alternatively, set the pyranometerup on a tripod and carefully align it to match the azimuthand tilt angle of the modules. The tripod method requiresmeasurements;otherwise, the powerestimate will haveso much uncertaintythat all other factorsbecome meaningless.Building Large Commercial Tracking Systems ForOver 28 Years!• Standard 16-panelsystem is designedfor 90 mph winds!• For huricane zones,we have a 12-panelsystem rated for150-mph winds!Tracking systemPrice:$4,980.00(Designed to tyour solar panels.)We also make a single-pole xedsystem with a safe, easy winter/summeradjustment. (Sept 21: loosen 2 bolts &adjust crank to winter & tighten bolts.March 21 reverse.)System cost: $3,200(Designed to t your solar panels.)The advantages of a pole-mountedsystem over a roof-mount:• Less Expensive ~ No Roof Leaks• Operates Cooler & More Ef ciently• Winter/Summer Adjustment For More GainThe Future Is Now!20KW system with(6) 3.36KW tracking panels.SOLAR(A Division of DH Satellite)600 N Marquette Rd, Prairie du Chien WI 53821608-326-8406 ~ 608-326-4233 (fax)www.dhsolar.net ~ 800-627-9443solarprofessional.com | SolarPro 49

PV System Commissioninga compass and inclinometer, but it isconvenient if there is a sunny spaceto set up the tripod near the inverter.Make sure that readings on thepyranometer and inverter can betaken within a few seconds of eachother: either with two people andphones, radios or shouting; or withone person when inverters are nearthe pyranometer setup.Write down the pyranometerreading in W/m 2 .Write down the inverter poweroutput in W or kW.Repeat twice more, alternatingback and forth between the pyranometerand the inverter, for a totalof three alternated readings on each.Alternating three times between thetwo devices is a good approximation of “simultaneous” forthis type of measurement.If the variation between readings is small, less than 2%,for both inverter and pyranometer, move on to the nextinverter and array. If the variation is large, start again andrepeat the alternating readings until three consistent valuesare measured.Finally, average the three irradiance readings and thethree inverter power readings. These are the values to usewhen verifying performance.After you have calculated the expected performance andmeasured the actual performance, a simple comparison helpsyou determine whether the system has been successfullycommissioned. Depending on the certainty of the assumedSA simple comparisonof expected andmeasured performancedetermines whetherthe system has beensuccessfully commissioned.The actualperformance shouldbe within about 5%of the expectedperformance.and measured factors, the actual performanceshould be within about 5% of theexpected performance.Some of the necessary measuring andreporting can be automated or accomplishedmore easily by using an installedmonitoring system, also known as adata acquisition system (DAS). Often,these systems report inverter ac power,irradiance and module cell temperature.Some even measure and report individualstring or module outputs. Duringinitial system commissioning, however,the DAS may not be properly calibratedor the network it relies on may not be setup. Further, the DAS reporting shouldbe verified by the on-site field measurementspreviously described.Case Study: 50 kWp Commercial System, MultipleInvertersPV array capacity: 50,310 W STC; 234 SunPower SPR-215-WHT-U modulesInverters: Six SunPower SPR-7000m and one SunPowerSPR-4000mArray installation: Thirty-six of the modules are on a muchsteeper roof plane than the others and are dedicated totheir own inverter.The system was originally commissioned, or partiallycommissioned, just after construction was completed in themiddle of the winter. There was some midafternoon shadingon parts of the array that resulted in overall system performanceof about 5% below the expected, continued on page 52Table 1: Inverter Test Results3/9/2009 Clear sky, no shadingInverter # Time Irradiance 1 Watts 1 Irradiance 2 Watts 2 Irradiance 3 Watts 3AverageirradianceAveragewatts1 1:03pm 840 2,970 842 2,979 843 2,977 842 2,9752 1:05pm 840 5,924 842 5,930 842 5,940 841 5,9313 1:06pm 842 6,010 845 6,030 848 6,041 845 6,0274 1:07pm 846 6,046 845 6,040 843 6,040 845 6,0425 1:08pm 847 6,044 853 6,057 855 6,075 852 6,0596 1:17pm 820 6,053 827 6,037 824 6,022 824 6,0377 1:19pm 1,060 7,057 1,095 7,059 1,078 7,055 1,078 7,05750 SolarPro | October/November 2009

$/W is soooo 2008.It’s all about $/kWh now.Introducing the UJ6 module seriesfrom Mitsubishi Electric212 to 235 wattsWith the solar industry shifting its focus from $/W to $/kWh, a module’s real-life energy performance is extremely important.Mitsubishi Electric PV modules have one of the highest PTC ratings in the industry and are well known for exceeding poweroutput expectations in real life conditions. All of our PV modules have a tight +/- 3% power tolerance, a 25-year poweroutput warranty, and are known for their exceptional quality and reliability.In our new UJ6 series, we’ve not only increased the number of cells per module from 50 to 60, we’ve also improved the cellefficiency to bring you more power per square foot. Mitsubishi Electric PV modules have some of the most innovative safetyfeatures in the industry including a triple-layer junction box, 100% lead-free solder, and a back protection bar for extrasupport. The new modules range in size from 212 watts to 235 watts and are designed for roof mount or ground mountcommercial installations.For more information pleaseemail pv@meus.mea.comcall 714-236-6137 or visitwww.MitsubishiElectricSolar.com

PV System Commissioningunshaded value. Because of the winter shading,the system was recommissioned 3 monthslater, when the weather was clear and therewas no shade. However, there was slight modulesoiling after 3 months (module soiling factorset to 0.99). Multiple irradiance and powerreadings were taken for each inverter, withresults summarized in Table 1 (p. 50).Inverter 1 is the 4,000 W inverter with 18modules, whereas the other six are 7,000 Winverters with 36 modules each. The 36 moduleson Inverter 7 are installed on a steeperroof, which is clearly a great angle for the earlyMarch sun, as seen by the higher irradiance inthat module plane and higher production onthat inverter. In addition, the 36 modules onthe steeper roof plane receiving more irradiancewere operating at a higher cell temperature(42°C) than the other, lower-angle modules (35°C).Temperature factor. The temperature factor, K T, is calculatedas follows: K T= 1 + (C T× (T C− T STC)). In this case, thetemperature coefficient of power, C T, is −0.38 %/°C , as suppliedby the module manufacturer.The measured cell temperature, C T, is 35°C for Inverters1 through 6 and 42°C for Inverter 7. The STC reference temperature,T STC, is 25°C. The temperature factor for Inverters 1through 6 is therefore:K T= 1 + (C T× (T C− T STC))K T= 1 + (−0.38 %/°C × (35°C − 25°C))K T= 1 + (−0.38 %/°C × 10°C)K T= 1 + (−0.038)K T= 0.962Table 2:System Derating FactorWiring losses 0.98Module soiling losses 0.99Module mismatch 0.97Module nameplatetolerance0.99Shading 1.00Inverter efficiency 0.955Age 1.00System derating factor K S0.89Using the same methodology,the temperature factor, K T, forInverter 7 is calculated as 0.935.System derating factor. Table 2illustrates how this is calculatedusing the appropriate subfactors.The system derating factor, K S, forthis system is calculated at 0.89.Irradiance factor. The averagerecorded irradiance values, dividedby the STC reference value of 1000W/m 2 , provide the system’s irradiancefactor, K I. For example, theaverage irradiance during testingof Inverter 1 is listed in Table 1 as842 W/m 2 . The irradiance factorfor Inverter 1 is therefore 0.842 (842W/m 2 ÷ 1,000 W/m 2 ).The performance test results for this system are providedin Table 3. Clearly, the system was performing quite well.Ongoing performance verification is simplified since the dataacquisition system at the site monitors individual inverterproduction, as well as irradiance and cell temperature.Establish performance BenchmarksAnother important function of commissioning is to establishperformance benchmarks for the PV system. Carefully measuringand documenting performance at the beginning ofthe system’s lifetime provides a standard to measure againstduring future maintenance. If the system appears to be performingwell, follow-up measurements might not be takenuntil the next scheduled maintenance. For example, on aresidential system without continuous continued on page 54Table 3: Performance Test ResultsInverter #Quantity ofmodulesSTC wattsper moduleTotal STCwattsSystem deratingfactor (K S)Irradiancefactor (K I)Temp. factor(K T)Predictedwatts acMeasuredwatts acMeasured/predictedwatts ac1 18 215 3,870 0.89 0.84 0.962 2,789 2,975 107%2 36 215 7,740 0.89 0.84 0.962 5,575 5,931 106%3 36 215 7,740 0.89 0.85 0.962 5,600 6,027 108%4 36 215 7,740 0.89 0.84 0.962 5,597 6,042 108%5 36 215 7,740 0.89 0.85 0.962 5,644 6,059 107%6 36 215 7,740 0.89 0.82 0.962 5,458 6,037 111%7 36 215 7,740 0.89 1.08 0.935 6,941 7,057 102%Total 234 215 50,310 — — — 37,667 40,129 107%52 SolarPro | October/November 2009

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PV System Commissioningmonitoring, the system owner can hang a clipboardnext to the inverter and write down the inverter outputat noon on the first sunny day of each monthor the first sunny weekend day. These numbers willform a pattern over the years, and any drop in performancecan be identified and investigated. Of course,the initial numbers must meet expected values. If thebenchmark performance is unnecessarily low, thesystem may never meet its expected performanceand no one will notice.Similarly, after a year passes and system ownersreceive the first “true-up” bill from the utility to findthey owe more than expected, they may point fingersat the integrator. The integrator need only repeatthe measurements taken and documented the yearbefore at commissioning. If these match, the systemwas undersized, or performance was overpromisedfrom the beginning, or the customer has addedloads that were not anticipated. Benchmark data isparticularly useful in this scenario, especially if thecustomer formally accepted the results at the initialcommissioning.Acceptance / certificationVarious parties have varying degrees of interest inaccepting the PV system. In fact, one of the reasonsto perform commissioning is to fulfill acceptance testrequirements. Typical acceptance tests include:Does the PV system operate in normal grid-tie modewhen presented with normal operating conditions, suchas in the presence of sun and utility power?Is the ratio of measured system power output to predictedpower output of the system at least 0.95?Most local jurisdictions will not check to makesure the PV system performs as designed. As with theNEC and most building codes, the AHJ’s main concern is thatthe system is safe. Often, the permit is signed off before thesystem is ever turned on.Similarly, most utilities are satisfied if the system designpasses the engineering review and the proper disconnects areobserved at inspection. Occasionally, the utility will requirethat automatic shutdown of the inverter upon grid failure bedemonstrated. But a utility is rarely concerned with the measuredpower production values of the system.The PV integrator installing the system should be thefirst to pay attention to the initial system production. Frominstallers to system designers to company CEOs, pride intheir final product is linked to kilowatt-hour production.The integrator should not internally accept the installationuntil proper operation and production is verified.Naturally, the system owner is the party with the mostinterest in accepting the newly commissioned PV system.Performance verification After measuring cell temperature, irradianceand inverter output power, the author uses a laptop to verify thatsystem performance is within 5% of expected values.The owner will count on the system to produce the expectedpower for several decades. If the owner is a PPA provider, itusually requires very strict acceptance testing. Funding ofthe project, and the next project, is highly dependent on thepower produced from the system. The original PPA ownermay own the system for only 5 years, at which point it mustbe demonstrably in good working order so that the “fairmarket value” buyout price remains as high as possible.TrainingAs part of the commissioning process, the PV integratorshould train the owner on basic system operation. Thistraining should include a physical walkthrough of theentire system, especially noting disconnect locations andprocedures. Inverter operation should also be reviewed,including any display screens and status lights. Significanttime should be dedicated to studying the monitoringsystem, if one is installed. The owner continued on page 56shawnschreiner.com54 SolarPro | October/November 2009

PV System Commissioningshawnschreiner.comCommissioning forms Keep completed commissioningchecklists and forms for internal use. The system ownermay also require these as part of the O&M or acceptancedocumentation.should be clear on how to access the monitoring systemdisplay. The owner will need the URLs and passwords if theDAS is Web based, and will need to know how to navigatethat display, how often to look at it, what to look for andhow to interpret alarms.The integrator and owner should also review all systemdocumentation, including O&M manuals and warranties. Ifa maintenance contract is included, the scope of the contractshould be reviewed and the schedule and first maintenancevisit should be agreed upon.Increasing Emphasis on CommissioningOther benefits to the owner of commissioned PV systemscome from acceptance, recognition and financialawards from third parties such as green-building certificationorganizations and rebate administration agencies.For example, one of the prerequisites for the Energy andAtmosphere credit category for Leadership in Energy andEnvironmental Design (LEED) certification is the commissioningof all building energy systems, including thePV system. Further, PV system commissioning explicitlyrequires performance verification. In other words, if thePV system performance is not verified, the building is noteligible for 25% of the total available LEED points. Onceperformance is verified, the PV system itself can earn upto three credit points towards certification. For manynew commercial buildings with PV, LEED certification isa big deal. The PV commissioning agent needs to coordinatewith the LEED building commissioning authority toensure proper documentation.Although rebate programs vary from state to state andeven from city to city, most require an upfront predictionof system performance, upon which rebate dollar amountsare based. In California, the Expected Performance–BasedBuydown rebate is based entirely on the expected performance,as the name implies. However, for larger systems—currently systems over 50 kW, but in 2010 everything over30 kW—the rebate is entirely based on performance. Energyproduction is metered and rebates are paid based on kWhproduction. Clearly, the system owner or other entity receivingthe rebate money has a large incentive to ensure thatthe system performs as expected. Similarly, the New SolarHomes Partnership rebate amount is based on expectedperformance, but actual payment is granted only after formalsystem acceptance. For acceptance, site temperatureand irradiance measurements are required. The inverterdisplayedpower output must match the expected power outputcalculated for the measured irradiance and temperaturevalues. In addition, several markets have recently adoptedfeed-in tariffs to stimulate PV installations.The overall trend is clear. As performance based incentivesand feed-in tariffs become more popular in the US,system owners will demand—and integrators will need toprovide—excellent commissioning and performance verificationservices.Special thanks to Sun Light & Power for arranging siteaccess for project photography included with this article.X Web exclusive Go to so l a r p ro f e s s i o n a l.co m/we b e x c l u s i v ef o r th e following sa m p l e, d o w n l o a d a b l e do c u m e n t s: p r e c o m m i s s i o n i ngc h e c k l i s t, c o m m i s s i o n i ng fl o w c h a r t, p e r f o r m a n c e verification fo r m.g CONTACTBlake Gleason / Sun Light & Power / Berkeley, CA /blake@sunlightandpower.com / sunlightandpower.comResources:Building Commissioning Association / bcxa.org (Sample commissioningrequirements at: tinyurl.com/mrbw68)Clean Power Finance / cleanpowerfinance.comClean Power Research / cleanpower.comEPBB rebate calculator / csi-epbb.comLEED / usgbc.orgPVWATTS / nrel.gov/rredc/PVWATTS56 SolarPro | October/November 2009

Solar ThermalBy Bristol Stickney and Boaz SoiferIn many cases, solar heating is the mostenergy effective renewable energy technology andis therefore cost effective as well. Thermal collectorsconvert solar energy to useful heat aboutfive times as efficiently as PV modules convert itto electricity. According to the US Department ofEnergy, space heating and cooling make up about53% of US residential energy usage, with hot wateradding another 16%. Since solar heat is relativelyeasy to collect and heating, cooling and hot waterdemands represent such a large portion of ourenergy usage, it is likely solar heating will becomemore mainstream.shawnschreiner.comSolar Thermal TodaySince the oil embargoes of the 1970s and the Carter administrationtax credits, certain types of solar heating systemshave gone through several generations of market growth.Solar pool heating systems are a mainstay of the industry,with thousands of established installers. Solar domestic hotwater systems are being packaged by dozens of manufacturers,and installations of these nearly plug-and-play systemsare on the rise.Both of these system types are relatively easy to design andinstall, as each addresses a single heating load and each typicallyinterfaces with automated backup heating systems. Solarpool heating systems usually preheat a boiler or operate independentlyfrom the backup boiler. Most packaged solar hotwater systems include a storage tank with an electric elementthat comes on automatically when solar heat is insufficient.58 SolarPro | October/November 2009

Hydronics:Collector Comparisonand SelectionSeasonal solar pool heating systems often have the advantageof using low cost unglazed collectors, and domestic hot watersystems have the advantage of year-round usage, for annualsavings that impact system economics and ROI.Combination (combi) systems, however, have seen muchslower market growth than their simpler cousins. This is dueto their inherent complexity, which involves the integrationof multiple heating loads in a building and regulatingthe interaction between solar and backup heating sources.Square Footage of Collector Shipments in the USby Type and ApplicationCollector type Application Sq. ft. shipped in 2007Low temperature Pool heating 11,917,000metallic andDomestic hot water 4,000nonmetallicSpace heating 63,000Mediumtemperatureflat platePool heating 158,000Domestic hot water 951,000Combi-systems 68,000Table 1 When system technology is packaged in a manner that is easy tospecify and install, the market size can be substantial. Conversely, whenthe system learning curve is steep, as in the case of solar space heatingsystems, the market remains largely untapped. The figure above indicatesinstallation of only 354 combi-systems nationally. Energy Information Administrationdata from 2007, published in 2008When system technology is packaged in a manner that iseasy to specify and install, the market size can be substantial,as Table 1 illustrates. Conversely, when the system learningcurve is steep, as in the case of solar space heating systems,the market remains largely untapped.Solar space heating has great potential to become as popularas pool heating and domestic hot water systems have. Forthis to happen, we need prepackaged, integrated solutionsthat address system functions that currently require customization.Expanded federal solar tax credits,state incentives and financing programs areboosting interest in integrated systems. Otheradvances, such as renewable energy credits(RECs) for solar heat produced (analogousto those enhancing PV system economics inmany states), will make solar heating evenmore affordable. It is likely that demand forintegrated solar heating systems will increase,and the possibility of dramatic industry growthis great. Installers who have a good understandingof the technology and its applicationsshould see their businesses grow.Towards that end, in this article we focuson solar heat collectors—specifically glazedhydronic collectors. For decades, these collectorshave proven themselves to be effectiveat providing hot liquid for a variety of heatingapplications, including domestic hot water(DHW), hydronic (hot water) space heat, radiantwarm floors and year-round heated pools.solarprofessional.com | SolarPro 59

Solar Thermal HydronicsCollector EfficiencySolar collector thermal efficiency can be broadly defined as thefraction of available solar energy converted into useful heatduring a known period of time. This value can be calculated—by measurement or modeling—instantaneously, hourly, dailyor averaged in other ways. Divide the useful energy deliveredby the solar energy available and you get the efficiency, whichcan be expressed as a decimal fraction or as a percent. It isoften referred to by the Greek letter Nu (η).In sales literature, sometimes the only mention of efficiencyis a single number, for example η=0.71. This mightlead you to expect that a given collector will always convert71% of the solar energy into heat. In most cases, however, ηrefers to the best possible theoretical efficiency for the collectorin question, which is also known as the optical efficiency.This is the combined efficiency of the transparentcover and the absorber, and it is identified more properlyby its own symbol (ηO). While it may be interesting to comparethe optical efficiency of one collector to another, thishas little to do with its operational efficiency or heat outputwhen installed.The thermal efficiency of a solar heat collector is notstatic and cannot be accurately expressed as a single number.It changes with the operational conditions, such asweather and temperature. This can make a fair comparisonof one collector to another difficult, since panels come indifferent sizes, are made of different materials, and can beused in countless different climates and temperature applications.Clearly there is a need for standard ways to test andcompare solar heat collectors; in the US, those standards aremaintained by the Solar Rating and Certification Corporation(SRCC).Three main variables can affect the efficiency of any heatcollector during its normal operation:• Collector fluid inlet temperature (T i) in °F• Outdoor ambient temperature (T a) in °F• Solar radiation intensity (irradiance, I) in Btu/hr/ft 2T iis determined by the purpose of the system. For poolheating, the temperature of the water returning from thepool to the collectors may be around 80°–90°F. When thesystem is directly heating a warm mass floor or hot tub,the return fluid may be around 100°–120°F. When heating adomestic water tank, the return fluid might be 120°–160°F.When charging up a heat storage tank for fan coil, fin tubeapplications or other higher temperature processes, the fluidreturning to the collector may be as high as 180°F.Higher return temperatures have a negative effect oncollector efficiency. That is why the common wisdom amongsolar designers has always been “A cool collector is an efficientcollector.” When the collector stays cool on a sunnyday, it means the coolant is carrying away the solar heat, soit is not building up in the collector. Extremely hot collectorscan indicate a coolant flow failure, with corresponding collectorefficiency near zero. Keeping your solar fluid coolerresults in a higher thermal collector efficiency, which meansmore heating energy collected per day. One of our favoriteapproaches for home heating is to use the concrete mass ofthe warm floors to keep the collector fluid cool. In DHW systems,using a slightly larger hot water storage tank will keepthe solar fluid temperature cooler, as long as the design stillprovides useful DHW temperatures under common localweather conditions.Warm T ahas a positive effect on solar heat collectors. Thewarmer the weather is, the more efficient a collector will be.This is because the undesirable heat loss—from the collectorto the outdoors—is driven by the temperature differencebetween the inside of the hot collector and the outdoor air.Heat flows from hot to cold; the greater the difference, thefaster it flows. This is known as back loss from the collector—heatloss back to the ambient environment. It includesthe heat lost from the collector's glass cover, the insulatedback and the side frames of the enclosure around the hotabsorber plates, tubing and manifolds. Manufacturers takegreat pains to reduce these back losses by careful design ofthe glazing system, air or vacuum spaces, selective blackabsorber surfaces that minimize heat loss by re-radiationand insulation details.Irradiance drives the solar heat collection process. Allother things being equal, the more intense the solar radiation,the higher the efficiency.These three efficiency variables can be combined intoa single expression of collector performance known as theinlet fluid parameter (p), which can be calculated as:p = (T i– T a) ÷ IThe temperature difference is often called the delta T andcan be written as:p = (Δt) ÷ IThe SRCC publishes the delta T using the symbol (P), sothe equation then appears as:p = (P) ÷ ISolar collector efficiency is most accurately expressed asa function of this parameter. Testing facilities use this mathematicalrelationship to calculate solar collector efficiencydata, and it is available from most collector manufacturers.This information is most commonly presented in the form of alinear graph, as shown in Graph 1 (p. 62). continued on page 6260 SolarPro | October/November 2009

Harvest the power oftheSeason after season,the sun gives its light to the earth,allowing life to bloom.Every day a limitless crop of free,clean energy reaches our planet.Stiebel Eltron manufactures all the tools youneed for a successful thermal solar harvest.And we’ve been doing so since 1976.From our highly efficient flat plate collectors andstorage tanks to our complete line of mountinghardware, pump stations, controllers, andaccessories, we have it all.SunStiebel Eltron is your one stop source for thermal solar products.SOLKIT 2 includes:2 x SOL 25 PLUSFlat Plate CollectorsSBB 300 Plus Storage TankPump station withSOM 6 Controllerwww.stiebel-eltron-usa.comBecause every installation isdifferent, we have a full line ofSOLKITS and mountinghardware kits available. Allcomponents and accessories areavailable for individual sale.Simply the BestTOLL FREE 800.582.8423info@stiebel-eltron-usa.com

Solar Thermal HydronicsCollector thermal efficiency(decimal %)1.00.90.80.70.60.50.40.30.20.10Unglazed flat plate0.1Glazed flat plate0.2Intercept = 0.86Slope = –3.040.3SRCC publications provide a variety of collector testresults, including the slope and the intercept data for eachcollector tested. The slope and the intercept allow you to drawa straight line on a graph that defines the collector efficiencyfor any conditions of p. Graph 1 shows the efficiency of threedifferent types of collectors: glazed flat plate, unglazed flatplate and evacuated tube collectors. The slope is the (negative)rise over run of the line as it runs downhill to the right;the intercept is the point found on the vertical axis.Keep in mind that this represents the collector thermalefficiency only, which is not to be confused with the systemthermal efficiency. The system thermal efficiency is complicatedby pump and control parasitic energy consumption,heat loss from piping, heat exchanger efficiencies and heatstorage losses, among other factors.0.40.5Inlet fluid parameter0.6T i– T aIEvacuated tube0.7Intercept = 0.52Slope = –0.19Intercept = 0.76Slope = –0.820.80.9ºF x ft( ) 2 x hr( )1.0 1.1Graph 1 Inlet fluid parameter presented as a linear graph. Adapted from idronics #3,January 2008, published by Caleffi Hydronic SolutionsBtuon the SRCC Web site (see Resources),which also provides a detailed list of thetest results for collectors available in theUS market (as long as the manufacturerapplied for and received SRCC certification).The list is continually updatedso that new products are listed as theirtesting is completed.The scope of the SRCC programincludes solar heating systems forswimming pools and recreational heating,space heating and water heating.When testing and certifying solar heatcollectors, the SRCC follows the OG-100standards. The OG-300 standards applywhen testing solar water heater systems.The SRCC tests the durability ofthe solar equipment and determinesthermal performance under prescribedrating conditions. Following the samestandards for every solar product yieldsreasonably comparable results.The following documents can be downloaded from theSRCC Web site. They provide specific details and comparativeresults for the collectors and water heating systems testedunder the SRCC certification and rating programs.Summary of SRCC Certified Solar Collector and WaterHeating System Ratings: This publication lists abbreviatedperformance ratings for solar collectors and systems,typically one line of results per product tested.Directory of SRCC Certified Solar Collector Ratings: Thispublication presents construction and rating informationon certified solar collectors. It is a more completelisting of the test results, typically providing one page ofresults for each product tested.SRCC Test ReportsIn the US, the SRCC is the national clearinghouse for standardcomparative test results for solar heat collectors and packagedsolar water heater systems. It was founded in 1980 as anonprofit organization with the primary purpose of developingand implementing certification programs and nationalrating standards for solar energy equipment. The organizationadministers a certification, rating and labeling programfor solar collectors and for complete solar water heatingsystems. Rating and labeling has become more important toinstallers and owners in recent years because solar tax creditrules in the US generally require an SRCC rating.All these ratings can be found in the SRCC database,organized side by side for easy comparison. This data is freeDirectory of SRCC Certified Solar Water Heating SystemRatings: This publication presents schematics andratings for certified solar water heating systems, typicallyone page of information per solar water heatersystem tested.Annual Performance of OG-300 Certified Systems: Thispublication provides estimated annual performance ofSRCC certified systems for various locations. It comparesthe performance of solar water heater systems in differentUS cities.If you are new to the SRCC test reports and interestedin comparing solar collectors, we c o n t i n u e d o n p a g e 6 462 SolarPro | October/November 2009

®Discover the benefits of our dependablesolar hot water innovations.Simply put, Heliodyne products keep working. Thousands of systems installed in thelate 1970’s are still running smoothly. What’s more, their “plug & play” designsmean less installation time and a better bottom line for your business. And like allour products, the GOBI ® solar collector (featured above) is made in the USA, andcomes factory-tested to 300 psi, with hassle-free American fittings. With so manyinnovative designs, and dedicated service & support, we’re a dependable leader youcan trust. So enjoy the benefits of a better tomorrow, by giving us a call today.Visit us at www.heliodyne.com, or call 1.888.878.8750 for information about us and our products.See us at SOLAR POWER INTERNATIONAL 2009 • October 27-29 • Anaheim, CA • Booth # 2476Heliodyne, Inc. • 4910 Seaport Avenue • Richmond, CA 94804T: 510.237.9614 • T: 1.888.878.8750 • F: 510.237.7018Information & Support: info@heliodyne.comSales Inquiries: sales@heliodyne.comwww.heliodyne.comEXCELLENCEBY DESIGN ®

Solar Thermal Hydronicsrecommend starting with the Summary of SRCC CertifiedSolar Collector and Water Heating System Ratings, whichpresents two useful collector ratings:• Linear efficiency graph results (given as a slope andan intercept) per square foot of collector• Daily collector heat output in “Category C” conditions(moderate operating conditions), allowing aquick comparison of heat delivery when comparingone collector to anotherFor the most comprehensive listing of SRCC collectorratings, refer to the Directory of SRCC Certified Solar CollectorRatings, which is packed with useful data. Each pagecontains heat output test results, the gross area, the netaperture area, weights and capacities, construction materials,and the pressure drop through the collector at variousflow rates. The real meat of the test outcomes appears as efficiencyequation results, which are explained in detail below.Finally, each page includes incident angle test results thatcan be used to model the performance of the collector whenthe sun is not directly facing it.We have created an Excel spreadsheet that contains datafor most of the SRCC listed glazed solar heat collectors. Thedata for each individual collector is summarized on one linefor easy comparison. The file is available for download atsolarprofessional.com/webexclusive.Making Sense of SRCC RatingsThe OG-100 standard for each solar collector includes a testto prove that the collector can stand up to high temperaturesolar stagnation and other harsh conditions. The finalresults include not only the slope and intercept of the linearcollector efficiency graph but also the heat output of thecollector under five different standard temperature and threedifferent solar irradiance conditions. These ratings representsolar heating jobs that range from very easy to very difficultand are presented in the following simplified categories:Category A: pool heating (warm climate) T i− T a= −9°FCategory B: pool heating (cool climate) T i− T a= 9°FCategory C: water heating (warm climate) T i− T a= 36°FCategory D: water heating (cool climate) T i− T a= 90°FCategory E: water heating (cold climate) T i− T a= 144°FResults from each category are presented for three solarirradiance conditions defined as follows:Clear day: 2,000 Btu per square foot per dayMildly cloudy: 1,500 Btu per square foot per dayCloudy day: 1,000 Btu per square foot per dayA collector that is capable of producing heat under allof these standard test conditions will have 15 optional heatoutput ratings; see Table 2 for an example. In a briefer summaryincluded in the Summary of SRCC Certified Solar Collectorand Water Heating System Ratings, and shown on thecollector specific stickers, only Category C, Clear day resultsare given for quick comparison.The SRCC provides information like that shown in Table2 to help you choose the right performance rating fromthe table’s grid. The fine print just below the grid can alsohelp guide you to the right heating category. For example,if you are doing water heating in a cool winter climate, thefine print guides you to Category D. The c o n t i n u e d o n p a g e 6 6Excerpt from SRCC OG-100 Certification ResultsCATEGORY(Ti-Ta)Megajoules Per Panel Per DayCLEARDAY23 MJ/m2-dCOLLECTOR THERMAL PERFORMANCE RATINGMILDLYCLOUDY17 MJ/m2-dCLOUDYDAY11 MJ/m2-dCATEGORY(Ti-Ta)Thousands of Btu Per Panel Per DayCLEARDAY2000Btu/ft2-dMILDLYCLOUDY1500Btu/ft2-dA (-5°C) 41 31 21 A (-9°C) 39 29 20B (5°C) 37 27 17 B (9°C) 35 26 16C (20°C) 32 22 12 C (36°C) 30 21 11D (50°C) 21 12 3 D (90°C) 20 11 3E (80°C) 11 3 – E (144°C) 10 3 –CLOUDYDAY1000Btu/ft2-dA-Pool Heating (Warm Climate) B-Pool Heating (Cool Climate) C-Water Heating (Warm Climate) D-Water Heating (Cool Climate) E-Air ConditioningTable 2 A collector that is capable of producing heat under all of the SRCC’s standard test conditions will have 15 distinct heatoutput ratings, presented in both megajoules and Btu per panel per day.Courtesy solar-rating.org64 SolarPro | October/November 2009

Riverside Correctional FacilityPhiladelphia, PennsylvaniaA Buderus Solar SystemCase StudySee us at Solar PowerInternational in AnaheimOct 27-29 Booth 2376The “greening” of a prison facility through theinstallation of a Buderus solar thermal systemSince December 24, 2008, 800 inmates of Riverside Correctional Facilityhave been in hot water, but not of their own making. This hot water is madeby a Buderus solar thermal system, which is estimated to save the City ofPhiladelphia $1.1 million and prevent one million pounds of carbon emissionsover the estimated 25-year life of the system.Unveiled on December 4, 2008 by Philadelphia Mayor Michael A. Nutter,this is the fi rst solar thermal system installed in a large urban jail in the U.S.and is one project towards the Mayor’s goal for Philadelphia to becomethe greenest city in America. The system was paid for with $400,000 fromthe prison system’s budget (spread over 3 years) with additional fundingof $265,000 from the Mayor’s Offi ce of Sustainability. It is expected tocompletely pay for itself in 8 –10 years.The Riverside Correctional Facility, a multi-building complex, is the centralintake for all women sent to jail in Philadelphia. The solar system wasinstalled on one building with an average daily population of 800 that hadrecurring water heater failures. One project challenge was making thetransition to the new system without interrupting the existing hot waterservice for personal hygiene, laundry, and cleaning. Another challenge wasthe limited existing boiler room space.The Buderus solar system replaced 15-year-old direct-fi red water heaterswith 45 roof-top solar collectors, 15 indirect storage tanks, 2 dual-fuel backupboilers, and associated controller and pumps. The solar panels transfertheir heat to a closed, antifreeze-fi lled system, with “overheat protection”set to 265°F. The heat is transferred via dual coils to the water in the storagetanks. The back-up boilers provide additional heat, if needed, and are dualfuelto take advantage of the lowest energy costs.50 Wentworth Ave., Londonderry, NH 030531-800-Buderuswww.buderus.netwww.buderussolar.comComfortable. Efficient. Intelligent Heating.Project Quick FactsProject PartnersØU.S. Facilities, Phila. - Facility ManagementHerman Goldner Company, Phila. - ContractorØContact: Jim Childs, 267-346-2987J. Lorber Company, Phila. - DistributorØContact: Bruce Kershaw, 215-791-2783Philadelphia Mayor’s Offi ce of SustainabilityMichael A. Nutter, MayorØEquipment45 Buderus SKS 4.0 Flat Plate Collectors,Ømounted in 2 rows at a 40˚ angle facing SSE15 105-gallon Buderus Logalux SM400 Dual CoilIndirect Storage Tanks2 Buderus G515 1 million BTU Dual-Fuel BoilersØ15 Buderus KS0120 Solar Pump StationsBuderus TR0310 U Solar ControllerØCost$665,000SavingsØ1st Year: $54,9748-Year: $673,295 (based on 20% energy costØincrease)10-Year: $712,863 (based on 10% energy costØincrease)$1.1 million over estimated service life ofØ25 years1 million pounds carbon emissionsProject SizeØ1 building, 200,000 ft 2800 inmates average daily population

Solar Thermal HydronicsSRCC also provides figuresquantifying Btu/ft 2 per dayfor various locations acrossthe US. If you are working inAlbuquerque for example,the average solar radiationis over 2,000 Btu/ft 2 per day.The value on the Table 2 gridthat corresponds to this is20,000 Btu per panel per dayfor this particular collector.Using this number informsthe number of panels neededto provide enough heat foryour application.Graph 2 includes theheating category data andthe irradiance data fromTable 2 to show the collectorefficiency data in varioussolar heating categories. Therectangular blue boxes onthe graph represent solar/temperature categories. The left side of each blue box representsthe warmer/sunnier locations in the US. The right sideof each blue box represents the coldest/cloudiest locations.For example, if you have a Category C heating job, the collectorsshown in Graph 2 will perform to the left side of the CategoryC box in Albuquerque or Los Angeles and to the rightside of the box in Seattle or Boston.Using the RatingsSolar thermal systems designers can use the SRCC data tooptimize system design and performance estimates in variousways.Comparing collector heat output and cost. The SRCC heatoutput rating is very easy to use. If one collector puts out 33kBtu per day and another puts out 21 kBtu per day, the winnermight seem obvious. However, you still need to considerif the collector sizes are similar and if there are significantdifferences in cost, mounting hardware or piping hardware.The SRCC provides the following example to show howto compare the energy output for each dollar spent ondifferent collectors. How many Btu does a dollar buy ifspent on Collector #1 versus Collector #2? You can answerthis question by dividing the energy output by the cost ofthe collector.For example, you are considering a solar water heatingapplication. Collector #1 has a rating in Category C ( forwater heating) under the correct climate column of 21,000Btu (per collector panel per day). Collector #1 sells for $387.Collector #2 is rated at 33,000 Btu; it sells for $675. Thus:Graph 2 SRCC heating category and irradiance data allow designers to create graphicalrepresentations of collector efficiency in various heating categories.Collector thermal efficiency(decimal %)1.00.90.80.70.60.50.40.30.20.100Category B—pool heating (cool climate) T i– T a= 9ºFUnglazed flat plate0.25Glazed flat plateCooler fluid, warmer and sunnier weatherCategory C—water heating (warm climate) T i– T a= 36ºF0.50Collector #1: 21,000 Btu/$387 = 54 Btu/dollarCollector #2: 33,000 Btu/$675 = 49 Btu/dollarCollector #1 is the better buy, based on performance underthe test conditions alone. The higher the number of Btu perdollar, the more cost effective the collector—all other thingsbeing equal.Linear efficiency graphs. The SRCC collector efficiencyresults do not include the actual graphs, but rather theyprovide the mathematical descriptions that allow youto plot your own graphs. For example, you could developa spreadsheet to draw the graphs for you. Graph 1 (p. 62)has some points labeled as “slope” and “intercept” to indicatehow those numbers apply to the lines on a graph. Theslope is the rise over the run, just like the slope of a roof.For example, a slope of −0.5 means that as a line is plottedfrom 0 to 1 on the horizontal (x) axis, it drops by 0.5 unitson the vertical (y) axis. The intercept is the point where thesloping line crosses the vertical axis and defines the opticalefficiency (ηO). Since efficiency graphs always drop downwardsas they move to the right, they always have a negativeslope even though the minus sign is sometimes missing indata listings.Linear efficiency is based on the formula:η = A + B (Δt ÷ Ι)Category D—water heating (cool climate) T i– T a= 90ºFEvacuated tubeºF x ft( ) 2 x hr( )T i– T aI BtuInlet fluid parameterwhere η = collector efficiency; A = intercept = ηO = opticalefficiency; B = slope (negative); and (Δt ÷ Ι) = p = (P) ÷ I.0.75Category E—water heating(cold climate) T i– T a= 144ºF1.0Hotter fluid, colder and cloudier weather66 SolarPro | October/November 2009

The slope and intercept values provided by the SRCC testscan be plotted as shown in Graphs 1 and 2, then compared.Graphs 1 and 2 each show three sample linear efficiencycurves, and the comparison is striking. We can see the efficiencyof a glazed flat plate collector compared to an evacuatedtube collector and an unglazed flat plate collector. Asyou move to the right, the value of p (the inlet fluid parameter)increases, which means more severe conditions for ourcollectors, such as colder ambient air, hotter inlet fluid andmore cloudiness.For the sample collectors in Graph 2, the glazed flatplate collector (red) performs with a higher efficiency thanthe evacuated tube collector (green) anywhere to the left ofp=0.40. Both of these collectors are from the same manufacturer.This is a compelling reason why we still use a lot offlat plate collectors in northern New Mexico, since our solarheating conditions are typically on the left side of this graphand flat plate panels are generally lower in cost per squarefoot. If the price of an evacuated tube collector is muchhigher than a flat plate collector, the extra expense may notbe worth it unless you are to the right side of Category D orinto the Category E area.Gross area vs. aperture area. The SRCC uses the gross areaof the collectors in its calculations. Flat plate collectors typicallyhave a higher ratio of absorber plate area per square footof gross collector area than do evacuated tube collectors. Thelatter usually require more roof area to accommodate a givenamount of absorber plate surface. The gross area is the sizeof the top face of the collector, including the frames and thespace between the tubes. It defines the amount of real estatethat the panel will occupy. The gross area is not the same asthe net aperture, which is the size of the glass or other glazingmaterial through which sunlight can enter. Nor is it the sameas the absorber surface area, which can be even smaller thanthe glass surface.In Europe, a testing standard allows aperture area andabsorber area to be compared. This kind of data is available,for example, on the Solar Keymark Web site (see Resources).We used this data for the orange line on Graph 3 (p. 68), whichshows how much difference there is between efficiency calculatedusing the aperture versus gross area for one evacuatedtube collector. Manufacturer generated sales literature is notalways consistent—published values may be based on eithergross area or aperture area. When evaluating any collector’sperformance, make sure to read the fine print. You should keepin mind that the efficiency, based on either gross or net area,Balance of System Solutions for PV Integrators. Cables, Combiners,Fuse Boxes as well as Performance Monitoring Solutions.For details on SolarBOS products and solutions, simply send anemail to newproducts@solarbos.com or call us at 925.456.7744.www.solarbos.comsolarprofessional.com | SolarPro 67

Solar Thermal HydronicsCollector thermal efficiency(decimal %)1.00.90.80.70.60.50.40.30.20.100Unglazed flat plateis not a substitute for a collector’s estimated output under theconditions of independent testing.Efficiency curves. Another set of SRCC test results allowsan even closer look at solar heat collector efficiency. Somecollectors are more sensitive to extreme cold temperatures,and a second order efficiency equation is needed to documentthat effect. The SRCC publishes these second orderresults, which can be used to plot nonlinear efficiency curvesusing the efficiency equation:η= A + B (Δt ÷ Ι) + C (Δt) 2 ÷ ΙEvacuated tube, aperture areaEvacuated tube, gross area(T m– T a [K])where: η = collector efficiency; A = intercept = ηO = opticalefficiency; B = slope (negative); C = second order heat losscoefficient; (Δt ÷ Ι) = p = (P) ÷ I; and (Δt) 2 ÷ Ι = (P 2 ) ÷ I.Glazed flat plate10 20 30 40 50 60 70 80 90Inlet fluid parameter, ºK; T mequals mean collector fluid temperature; T aequals ambient temperature.Graph 3 Collector efficiency: second order curves Graphs that account for the temperaturedependence of a given collector allow for more precise efficiency curves. Examples plotted hereare based on an irradiance of 800 W per square meter. Adapted from a spreadsheet by Jan Erik Nielsen, SolarKeymark, European Solar Thermal Industry Federation (ESTIF), 2006Whether you use theSRCC data pages or plotthe efficiency graphs,you can see that this dataallows useful comparisonsbetween collectors.Keep in mind that whilethe graph data is normalizedper square foot ofcollector, the heat outputdata is not. The heat outputgrids show the heatoutput of each collector,and some collectors arebigger than others. Youcan divide the heat outputby the collector areato make a comparison persquare foot. In the onlinetable, this calculation hasbeen done for you for eachlisted collector.The SRCC data isobviously very usefulbut your choice of collector should not be based on thisalone. Your decision should also include reliability, compatibilityand serviceability as well as hardware accessories andinstallation details that enhance successful installation. Itis always a good idea to talk to someone who has a couple ofyears experience with the solar product you are consideringto find out how it holds up and performs in your climate.g CONTACT100X Web exclusive A c o m p r e h e n s i v e ta b l e th a t co n t a i n s da t a fo rm o s t of th e gl a z e d so l a r he a t co l l e c t o r s li s t e d by SRCC is pu b l i s h e din Ex c e l fo r m a t an d av a i la b l e fo r do w n l o a d at so l a r p ro f e s s i o na l.co m/w e b e x c l u s i v e. Th e da t a fo r ea c h co l l e c t o r is su m m a r i z e d on on e li n e fo re a s y co m p a r i s o n.The variable (C) is a heat loss coefficient that identifies temperaturedependence. The heat loss of a collector depends onthe temperature, and high values of C indicate a large temperatureinfluence or a collector that reacts badly to extreme temperatures.The higher the value of C the more hooked-nosedthe efficiency curve becomes. Graph 3 shows some typical efficiencycurves based on this equation. Temperature dependencehas its greatest effect to the right of the graph, which is wherethe most challenging conditions exist—extreme temperatures,high delta T and very hot fluid. Under moderate conditions inthe middle and left of the graph, the linear efficiency plot is typicallygood enough for comparison purposes.Bristol Stickney / Cedar Mountain Solar / Santa Fe, NM /deltat@cedarmountainsolar.com / cedarmountainsolar.comBoaz Soifer / Cedar Mountain Solar / Santa Fe, NM /deltat@cedarmountainsolar.com / cedarmountainsolar.comResourcesSolar Rating and Certification Corporation (SRCC) / 321.638.1537 /solar-rating.orgSolar Keymark / estif.org/solarkeymark68 SolarPro | October/November 2009

The Resurgence ofMicroinverterTechnologyBy Ron Burden and Joe Schwartz70 SolarPro | October/November 2009

Microinverters providesystem designers withalternatives to thetraditional centralizedinverter approach.The emergence of decentralized inverter ormaximum power point tracking (MPPT)equipment has set the industry abuzz inrecent months. Several companies haveeither introduced or are in the process ofdeveloping components that enable moduleorstring-level optimization, power processingor both. This development may result ina fundamental shift in the way some PV systems are designed, whatcomponents are specified and how systems are installed. The microinverter(micro) is the first technology in this product class to makesignificant inroads into the US PV market.Courtesy e2powered.comTHE CASE FOR MICROSPhotovoltaic arrays are subject to continually, and often rapidly,changing conditions that include irradiance, temperature and shadingpatterns. These parameters create current/voltage (I-V) curvesthat are both dynamic and complex. Additional obstacles to optimalenergy harvest, like module mismatch, are built into systems fromday one.Over the past decade, the dominant trend in string and centralinverter designs has been higher power equipment. Today, invertersused in residential applications typically range from 4 kW to 11.4 kW;250 kW, 500 kW and even 1 MW inverters are often specified in powerplant–scale projects. Higher power inverters drive down the costper kW processed; but as the capacity of the inverter increases, thegranularity of array MPPT necessarily decreases. If optimal energyharvest rather than lowest installed cost is the goal, bigger may infact not always be better.Proponents of decentralized system topologies argue that whilegains in inverter conversion efficiency are close to topping out, significantthroughput gains can still be wrung out of photovoltaic systemsthrough optimization at the string or module level. Instead of a singleinverter tracking the MPP of dozens, hundreds or even thousands ofmodules, solutions such as microinverters allow for optimization atthe most basic level—a single PV module.solarprofessional.com | SolarPro 71

Microinverter TechnologyCourtesy meridiansolar.com (2)Before and after In the “before” photo, Enphase microinverters are shown preattached to ProSolar rail and centered whereeach Sharp NE-170 module will mount. There are six branch circuits of 24 inverters (208 Vac). Meridian Solar chose micros forthis project because the barrel vaulted roof varies from 3° tilt for the row at the crown to 32° tilt for the row at the eaves.Decentralized approaches minimize the financial impactof component failures and system downtime. Many engineerscurrently employ multiple string or central invertersthat segment a system’s power processing. With this designapproach, equipment failures or scheduled maintenance willimpact only portions of the system. Microinverters push thesegmented approach further. In a microinverter based systeman inverter failure reduces system production by onlyone module, while the rest of the array continues to producepower unabated.MICROINVERTER TECHNOLOGY EVOLUTIONPrior to the introduction of Enphase Energy’s microinvertersin 2008, the “in the field” history of micros in the US waslimited. Two companies, neither of which currently manufacturemicroinverters, brought products to market in thelate 1990s: Ascension Technology and Netherlands basedNKF Electronics.Miles Russell and Edward Kern from Ascension Technologydeveloped the 300 W SunSine microinverter, which waspaired with an ASE 300 W module. SCHOTT Solar eventuallyacquired Ascension, and the SunSine product was sidelinedduring the transition. The introduction of the SMA SB700,a 700 W inverter that filled a similar small grid-tied systemniche, influenced this decision.NKF Electronics developed the OK4 inverter line, whichTrace Engineering brought to the US in the late 1990s. TheUL listed Trace MicroSine was short lived, however: Changesin UL 1741 requirements, relatively soft sales due in part tohigh cost per watt compared to the string inverter productsthat were becoming readily available and reliability issuesinfluenced Trace’s decision to pull the plug on the project inthe early 2000s. Over 80,000 of NKF Electronics’s OK4 inverterswere sold worldwide before Optelecom, a video solutionsprovider, absorbed the company and shut down its microinverterefforts.While these two early microinverters never gained anythingclose to significant inverter market share, micro manufacturerEnphase Energy has recently proven that a marketdoes exist for these products. So what changed in the lastdecade? PV industry veteran Sam Vanderhoof was involved,to varying degrees, with both the SunSine and MicroSineprojects, as well as some of the current micro products. Hesums it up: “In many ways, the potential benefits of microinvertersand distributed array optimization are the same nowas those promised in the late 1990s. Advances in power electronicsand monitoring functionality, coupled with the sheersize of the current PV market, allow companies to gain tractionin ways that were not possible a decade ago. The marketis ready for micros.”CURRENT MICROINVERTER ENVIRONMENTTwo manufacturers, Enphase Energy and Petra Solar, currentlyhave micro equipment in production and beingdeployed in the field. A few additional micro developers areon the radar, and numerous others are in the R&D phase.Enphase Energy. Petaluma, California based EnphaseEnergy was founded in 2006, released its first generationmicroinverters in July 2008, and has shipped over 100,000units to date. Enphase’s successful launch was aided by thecompany’s ability to offer module level monitoring via itsEnvoy Energy Management Unit and Enlighten Web basedanalytics and visualization package. Enphase micros arecurrently limited to the 60 Hz North American marketand include 175 W and 190 W units. In July 2009, Enphaseannounced its M210, 210 W ac microinverter, which is optimizedfor use with Sanyo N series modules and has a CECrated efficiency of 95.5%. Enphase plans c o n t i n u e d o n p a g e 7 472 SolarPro | October/November 2009

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Microinverter Technologyto have this product available in September 2009. Enphasemicros carry a 15-year limited warranty and are designedto operate at full power at temperatures as high as 150°F.Petra Solar. Headquartered in South Plainfield, New Jersey,Petra Solar has been supplying microinverters to utilitycustomers under nondisclosure agreements for morethan a year. Petra recently made its efforts public when itannounced plans to deploy 40 MW of single module, utilitypole–mounted systems using its SunWave micro. Thesystems will be owned and operated by New Jersey utilityPSE&G. Petra’s product suite includes the SunWave ACModule and the SunWave Communications system, whichallows centralized management of megawatts of singlepole-mounted systems. Petra appears to be positioning itselffor upcoming Smart Grid technologies, according to itssales literature: “Remote monitoring and control is achievedthrough an integrated communications network that createsan IP-based Smart Grid backbone when deployed inlarge scale.” Petra is expected to make its product availablefor commercial and residential scale applications.SolarBridge Technologies. In May 2009, SolarBridge Technologiesannounced it was seeking to raise $10–15 millionin investment capital. Formerly SmartSpark Energy Systems,Austin, Texas based SolarBridge focuses exclusivelyon microinverters and associateddata monitoring solutions for PVapplications. The company is targetingQ4 2009 for the release of itsmicroinverter, which is designed tobe the power-processing componentof listed PVAC modules.GreenRay. Based in Westford, Massachusetts,GreenRay announced inJuly 2009 that it had raised $2 millionin investment for manufacturing anddistributing a PVAC module. Initialmarketing efforts will be aimed at theresidential segment. GreenRay wasfounded in 2006 by a group of formerSCHOTT Solar employees and is ledby CEO Miles Russell. Russell wasinstrumental in the design and marketdevelopment of the AscensionSunSine microinverter. The companyhas not yet announced a timeline forproduct release.Exeltech. With a long track recordof inverter manufacturing for telecomand other stand-alone markets,Exeltech has been beta testing itsown microinverter solution. The FortWorth, Texas based company plansCourtesy meridiansolar.comto bring a listed module and inverter product to market inthe future.RELIABILITY IS PARAMOUNTWith the short-term history of the current microinverterproducts, considerable apprehension exists regarding productreliability. Because inverters generally fail at a higherrate than other PV components, the warranty for a centralizedinverter is typically 5 to 15 years, whereas the rest of thesystem can carry a warranty of up to 25 years. The fact thatmicroinverters are typically located in rooftop installations—where high ambient temperatures are the norm, and anynecessary replacement is likely time consuming—amplifiessome integrators’ reluctance to embrace the technology. Thisconservative stance is in many ways warranted.Over the years, integrators have taken their fair share oflumps due to inverter failures. While the reliability of invertershas seen significant improvement in recent years, manyseasoned PV professionals are still wary of distributing whatis typically the least reliable component at a module-by-modulelevel. Doing so significantly increases the sheer numberof the one component that is most likely to fail. Says GeoffGreenfield, owner of Third Sun in Athens, Ohio, “Any of us inthe industry have our stories of being ‘burned’ with a failedor subpar product. For instance,our company is still changingout inverters that were installedyears ago, and the manufacturerhas gone out of business. This wasafter careful due diligence. Wewere in good company—even Siemenswas bundling this inverterinto its system packages.” Greenfieldis referring to the AdvancedEnergy GC-1000 inverter.Power inversion at single modulevoltage levels reduces inverterstress and allows for a streamlinedcomponent architecture. This hasemboldened micro manufacturersto offer robust warranties on theirproducts. SolarBridge states thatits microinverter will carry a 25-year warranty. The 15 year warrantyCommunications gateway This EnphaseEnvoy gateway is installed outdoors in a NEMA 4enclosure and communicates with the microson the roof over ac wiring, using a proprietarypowerline carrier system. A standard Ethernetcable is used to make the connection to abroadband router.of the Enphase micros effectivelymatches the longest warrantiesoffered by string inverter manufacturers.In addition, Enphasehas been marketing a mean timebetween failure (MTBF) value ofover 300 years. MTBF should notbe confused c o n t i n u e d o n p a g e 7 674 SolarPro | October/November 2009

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Microinverter TechnologyCourtesy meridiansolar.comMonitoring micros The Web based Enphase Enlightenmonitoring system provides unprecedented transparencyand granularity into PV system performance. In this screenshot,module mismatch, dissimilar orientation or othertransient conditions result in per module output power rangingfrom 120 to 131 W. In some cases, significant variationexists even within a single row where all the modules share acommon tilt angle.with the expected life of an inverter; it indicates the statisticalprobability that a unit will fail under specific operatingand environmental conditions. In some ways the introductionof MTBF to the conversation has muddied the waters,since MTBF values for string inverters are not readily availablefor comparison. The bottom line for installers should bethe length of a product’s warranty; the associated fine print; acompany’s reputation for service and technical support; and,to the extent it can be determined, whether the company willbe in business and handling claims over the duration of thewarranty.THE CURRENT MICRO MARKET NICHESystem component packages that include Enphase invertersare being introduced to reduce the learning curve forac electricians new to PV system design and installation.In addition, integrators are generally employing Enphasemicroinverters in specific applications where there is a clearbenefit to the approach. These include sites with localizedshading or roofs with multiple hips, valleys and orientations.Integrators have found that the Enphase system’s granularmonitoring capability has boosted sales.The selective pattern for specifying microinverter basedsystems is in part due to a relatively severe undersupplyof Enphase products. However, in May 2009, Enphaseannounced it had secured $22.5 million in new financing.“We are experiencing exceptional demand for our microinvertersystems. This financing will be used to ramp up manufacturing,accelerate new product development and expandinto new geographic markets,” says Paul Nahi, EnphaseEnergy president and CEO. The company announced inJuly 2009 that it had successfully completed a manufacturingplatform shift and would be producing thousands ofunits each month in an effort to meet demand and reducelead times.Minimizing the impact of localized shading. Thorough shadeanalysis will always be an indispensable first step in systemsales and design. However, microinverters do change thegame to a degree. Module series string configurations aresignificantly impacted by such factors as shading, soiling,orientation and module mismatch. System designers whoseek to maximize energy harvest at a less than ideal site findthe distributed architecture of a microinverter system tobe advantageous. Shade producing obstacles like chimneyshave less impact on micro systems with module level MPPT.Higher density roof coverage may be possible at shade challengedsites with micro systems compared to string inverterbased designs.Travis Moller, a commercial sales manager with Austin,Texas based Meridian Solar defines the micro niche: “I seespace-constrained residential roof areas with partial shadingissues from chimneys, utility poles and so on, and multipleroof area orientations as the primary market. Additionally, Isee potential for microinverters on multitenant housing toconfigure a larger array to feed multiple units when space formultiple string inverters may not be available.”Simplifying design and installation. Two basic approachesare under way throughout the PV industry to meet theexpected installer workforce demand. The first is to trainelectricians in standard system design and installation. Thesecond, which jibes well with microinverter based systems,is to simplify system design and installation to flatten thelearning curve. Micro products eliminate the more complexaspects of system design—string sizing, inverter MPPTranges, calculations based on historical ambient temperaturesand the like all go out the window. What is left on thedesign side are calculations that ac electricians are intimatelyfamiliar with, including circuit ampacity, disconnectand conductor sizing.Prepackaged microinverter systems could potentiallystreamline sales and installation. Akeena Solar began shippinga microinverter version of its Andalay preengineeredsystem in May 2009. Over the next 2 years, Akeena expectsto include 100,000 Enphase microinverters in the Andalayproduct. The Andalay micro system currently uses SunTechmodules; however, the company is actively seeking othermodule manufacturing partners. continued on page 7876 SolarPro | October/November 2009

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Microinverter TechnologyOn a smaller scale, Hawaii Energy Connection (HEC) hasinstalled over 140 integrated solar power systems using Enphasemicroinverters. This volume makes HEC one of the more experiencedEnphase installers at present. Its KumuKit productincludes two standardized packages with array capacities of875 W and 1.75 kW. HEC has also installed three small commercial3-phase systems with Enphase inverters in the 12–14 kWrange. The packaged approach used by HEC and Akeena willlikely gain traction as micros gain market acceptance.Decreased installation time? While microinverters clearlysimplify system design, the jury is still out on installationtime saving. HEC’s Chris DeBone shares his experience:“There is not much labor savings for our residential kitpackages. Our installation teams install a 10-panel systemin about 6 hours, but the customer is getting about 10%more production [ from the Enphase systems] plus a cleanerinstallation. Our customers like the fact that there is no largestring inverter mounted on the side of the house.”Meridian Solar’s Moller was recently involved in a 25 kWEnphase installation—the first project utilizing micros inAustin Energy’s service territory. He states, “There was abit of a learning curve associated with installing Enphase,DPWSolarPro7.12x4.62Oct09 hires.pdf 7/23/09 4:26:51 PMand the installation took a little longer than usual due tothe challenging roof area. Overall, the Enphase producttakes about the same installation time as a string invertersystem. My understanding is that there may be morepotential time and cost savings available for smaller residentialsystems with fewer circuits than there was with thissomewhat larger installation.”James Reismiller, owner of Abundant Solar in Corvallis,Oregon, echoes other installers we surveyed: “In certainjurisdictions, there may be a reduction in installation costs,but with our regulations in Oregon, that has not been trueof our experience. For example, some jurisdictions do notrequire conduit for the ac wiring. Also, some utilities do notrequire the installation of certain equipment such as a roofmounted disconnect.”When and if the industry reaches the point of developingPVAC products in which the module and inverter are factoryintegrated, it is likely that a reduction in installation timewill be realized.Monitoring advantages. Enphase’s Web based monitoringsystem is a strong selling point for many integrators. HEC’sDeBone states, “90% of our customers continued on page 8078 SolarPro | October/November 2009

Microinverter Technologyuse the Enlighten monitoring system. We actually had a customerfind a defective PV module in a string of 15. We wouldnever have known that one panel was producing below itsmanufacturing tolerance if a string rather than microinverterapproach was used. That one panel would have loweredthe production of the entire string of modules.”Meridian Solar’s Moller had a positive experience duringthe bidding phase of a recent Enphase project. “Thedata monitoring package and module-level clarity was abig bonus in the client’s mind. They are [members of ] anarchitectural firm specializing in schools and see it as a toolto use when introducing solar to their clients.” Moller continues,“Providing the Enphase option did make our proposaland attention to detail stand out among the other bidsthey solicited.”THE NEC AND MICROINVERTERSThe NEC specifically addresses ac modules: Article 690.6(A)states the requirements of Article 690 pertaining to PV sourcecircuits shall not apply to ac modules, and that the PV sourcecircuit, conductors and inverters should be considered asinternal wiring of the PVAC module. The output of a PVACmodule is considered an inverter output circuit per Article690.6(B). A number of PVAC modules may be connected onthe same circuit, according to ampacity limitations, but thecircuit must be dedicated to the PVAC module(s) and terminateat a dedicated circuit breaker according to Article690.6(C). The micro products currently available do nottechnically qualify as PVAC modules as defined by the NECbecause the inverter and module do not carry a single ULproduct listing. However, this minor disparity has not causedsignificant permitting issues in the field.John Wiles addresses PVAC modules in Photovoltaic PowerSystems and the National Electrical Code: Suggested Practices,published in 2005. Wiles states, “There are no external dc circuitsin the PVAC module, and none of the dc code requirementsapply. Unlisted combinations of small listed invertersmated to listed dc PV modules do not qualify as a PVACmodule and will have to have all code-required dc switchgear,overcurrent and ground-fault equipment added.”The Enphase microinverter is designed to be a stand-aloneunit. This enables integrators to utilize the product in combinationwith most off-the-shelf modules, rather than beinglimited to a specific listed module and inverter pairing. However,this strategy appears to contradict the requirements ofArticle 690.6 to some degree. We followed up with Wiles, andhe clarified that, in his interpretation, the Enphase productdoes meet NEC requirements. Wiles states, “1. The moduleconnectors can serve as the dc disconnects. 2. The inverterhas a ground fault protection device. 3. The Code does notrequire any overcurrent protection when there is no source ofovercurrents that exceed the module series protective fuse.”Marv Dargatz, Enphase Energy director of engineering,expands on the intent of the NEC: “The dc disconnect requirementscontained in Article 690 are clearly intended for multiplemodule arrangements. Article 690.13 states that you mustprovide means to disconnect all current-carrying conductorsof a photovoltaic power source from all other conductorsin a building. By the very nature of the microinverter, thereis no mixing of dc source wiring with the building wiring.The Enphase microinverter connecting to a single module isclearly not a traditional string inverter and is closer in conceptto the PVAC module as defined in 690.2. In addition, the dialogand explanation in 690.14(B) states that, ‘there is no intent orrequirement to have a disconnecting means located in eachPV source circuit or located physically at each PV module.’Finally, the 2008 NEC has added 690.33 to allow module connectorsof the latching or locking type and requiring a tool foropening to disconnect the dc.”MOVING FORWARDIn a paper presented at the 2nd World Conference and Exhibitionon Photovoltaic Solar Energy Conversion held in Vienna,Austria, in 1998, Henk Oldenkamp, developer of the OK4inverter, stated, “In order to make ac modules a serious option,more attention should be given to the integration of the ac moduleinverter with the PV module itself.” Eleven years later, PVACproducts in which the inverter is truly integrated with the modulehave yet to be introduced to the mass PV market. However,product integration is clearly moving in that direction.String and central inverters will undoubtedly hold theoverwhelming share of the inverter market for the foreseeablefuture. These products have proven to be reliable andcost effective. Outside of beta programs, today’s micros havelogged less than 2 years of field time. One cannot help butwonder if they, too, will disappear like the microinvertersintroduced in the late 1990s. Will the current generation ofmicros represent a dead-end shoot on the industry’s evolutionarytree? It is possible, but in our opinion, not likely.g CONTACTRon Burden / SolarPro magazine / Ashland, OR /ron.burden@solarprofessional.com / solarprofessional.comJoe Schwartz / SolarPro magazine / Ashland, OR /joe.schwartz@solarprofessional.com / solarprofessional.comManufacturersEnphase Energy / 877.797.4743 / enphaseenergy.comExeltech / 800.886.4683 / exeltech.comGreenRay / 978.631.0509 / greenraysolar.comPetra Solar / 732.379.5566 / petrasolar.comSolarBridge Technologies / 512.637.6860 / solarbridgetech.com80 SolarPro | October/November 2009

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InterviewAnExperienced PerspectiveBlake Jones, Namasté SolarRocky Mountain Integrator Shines on National StageBlake Jones is the president ofNamasté Solar, a Boulder,Colorado based PV systems integrator.Blake cofounded Namasté Solar in early2005, implementing a unique businessplan that emphasizes conscientiousbusiness practices, holistic wealth andemployee ownership. Four years later,Namasté has grown from three to 55co-owners; it is a market leader inColorado, with a portfolio of more than750 projects totaling more than 4 MW.On February 17, 2009, Blake introducedPresident Barack Obama at the signingof the American Recovery and ReinvestmentAct in Denver.—SolarPro Senior Technical EditorDavid Brearley reached Blake by phoneto learn more about Namasté Solar andits recipe for success.DB: What are the market conditions inColorado that have enabled NamastéSolar to grow from three employees in2005 to 55 employees 4 years later?BJ: Our grid-connected PV market gotstarted with the passage of [Colorado’s]Amendment 37 in November2004. At the time, it was the 19th or20th state RES [renewable energystandard] or RPS [renewable portfoliostandard] to pass. It was significantbecause it was the first one passed byvoters, as opposed to state legislature.At the time, the RES was 10% by 2015and had a solar carve-out, mandatingthat 4% of that 10% come from solar.Of that 4%, half has to come fromcustomer-sited or distributed solar.That provided the foundation forthe market to explode. It took abouta year and a half before the law wasinterpreted, so it wasn’t until March2006 that the first incentive programwas launched. Since then, the stateCourtesy namastesolar.comBlake Jones, CEO Namasté Solar A civil engineer byeducation and training, Blake worked for a subsidiary ofHalliburton for 5 years before deciding to dedicate his lifeto the implementation of renewable energy technologies.legislature has doubled the RES to 20%by 2020, with the 4% solar carve-outintact. Of course, the RES doesn’t applyto all utilities in the state. It mainlyapplies to the investor owned utilities,of which there are two that cover 60%to 70% of the state population. About18 MW were installed in Colorado in2008, making it the third largest marketfor PV in the US.DB: What are the biggest challenges tocontinued market growth in Colorado?BJ: One of the biggest challengesthat we face in the solar industry isdependence on policy.It’s very difficult toplan a business in anuncertain, short-termpolicy environment.While everyone inthe industry sharesthat concern, herein Colorado we don’thave a good long-termoutlook like Californiadoes. The CSI [CaliforniaSolar Initiative]program is fantasticbecause it has a longtermoutlook. Thefunding is secured;you know exactly howrebate levels will bereduced based oncertain volumes. Wedon’t have that certaintyin Colorado.The problem weface is that Coloradois ahead of schedulein complying withits RES. Xcel Energy,the main utility, isplanning on scalingback its incentive program. So whileColorado currently enjoys leadershipstatus in the PV market, we’re facinga market cliff. We need to enact newpolicy to extend our market outlookwell beyond this year and to retain ourleadership position.DB: That’s a significant task. How hasNamasté Solar decided to allocateresources in order to meet that challenge?BJ: Great question. Some companiesput their head in the sand and hopesomebody else deals with the problem.Other companies c o n t i n u e d o n p a g e 8 482 SolarPro | October/November 2009

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Interviewstep up to the plate and say, “Hey, Iwant to be involved. I want to helpshape the market that feeds us.”We’re a company in that lattercategory. We’ve always had a full-timeperson dedicated to policy issues. We’revery actively involved in CoSEIA [ColoradoSolar Energy Industries Association].I was on its board for 3 years,and now one of my fellow co-owners,Eriks Brolis, is on the board. We thinkthat involvement is imperative. It’s notjust for the benefit of the market; it’salso a benefit to the company. Whenyou’re involved, you have a better ideaof what’s going on in the policy landscape.Getting that real-time informationhelps you make more informeddecisions about planning, about riskmanagement and about what to do. Fora solar company to have no idea what’shappening in the policy environment islike flying blind.From a short-term perspective,dedicating somebody full-time topolicy costs money. But over the longrun, it has a positive benefit. Whenyou’re actively involved, you get tomeet movers and shakers in the industry.You have a great chance for peopleto get to know you, the caliber of yourcharacter and the great work you do.Our involvement in policy may havecontributed to our being noticed bythe Obama administration, resultingin our presence at the stimulus bill–signing event.DB: That was a proud moment for theindustry, and a lot of people, includingmyself, were deeply moved by yourspeech. Thank you for representing theindustry so well.BJ: It was a tremendous honor to representall green industries. Of course,it was fantastic that Obama chose asolar company. He could have chosenany company in the green industries,but he chose a solar company, and wetook the responsibility very seriously.It was an amazing moment forthe solar industry. It really energized“There is a unique claim that we can make aboutgreen jobs: that green jobs aren’t just good for those of us that havethem; green jobs are good for everyone. There are widespread benefits,such that with every green job we create, our nation takes onestep closer toward achieving energy independence, strengtheningnational security, bolstering the economy, protecting the environmentand improving public health.”—Blake Jones of Namasté Solar, introducing President Barack Obamaprior to the signing of the Recovery Act in Denver, CO.Colorado, and it put pressure on thestate—in a good way—to do more forrenewable energy markets. The Presidentalso toured our installation at theDenver Museum of Nature & Science.DB: Namasté Solar is headquarteredin Boulder, but has a branch office inDenver. Other business owners in thePV industry must wrestle with when andhow to open a satellite office. How didyou make the decision to open a Denveroffice? Do you have other offices?BJ: No, we’re just in Boulder and Denverright now. When a PV integratorshould open a branch office is a toughdecision. We have a relatively easysituation because Boulder and Denverare very close to each other.From the start, even though ourfirst brick and mortar location wasin Boulder, we were doing a lot ofbusiness in Denver. We also have alot of people who live in Denver. Wewant their commutes to be as shortas possible. We want the emissionsfrom their transportation to be as lowas possible. We want to improve theirquality of life by having a place that’snear their home. We’ve had the Denveroffice for two years now and it makesgood sense for us.If people live in Denver but workout of a Boulder office, they’re not ableto participate in the local communityas well as they might otherwise. Wetake community participation veryseriously, which is why we love to haveoffices that are centrally located. It’stempting to get an office outside thecity in industrial areas where you havecheaper warehouse and office space.But we would rather pay more in orderto be centrally located.This is a great example of how wemeasure profit holistically. We thinkpaying more for rent actually contributesto a bigger bottom line. It’s easierfor customers to come see us; it’s easierfor us to commute by bicycle and bybus. We’re happier because our commutesare shorter and because thereare better places to go to lunch. It’s justeasier to interact with the community.DB: What about interaction betweenoffices? Were there technological andprocedural hurdles involved with startingup a branch office?BJ: Definitely. You need to work out alot of communication issues. It’s easyto have a meeting when everybody’sin the same office; it’s harder when youhave branch offices. There are phoneissues to resolve. There are IT issues.You may need to change your accountingsoftware to allow for multiplewarehouses, for example.We’re lucky that we got to open abranch office located so close to ourfirst office. It’s like an office with trainingwheels. We’re still able to have allcompanymeetings; people only haveto drive 30 or 45 minutes, and they canall carpool. We think that opening anoffice in another c o n t i n u e d o n p a g e 8 684 SolarPro | October/November 2009

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Interviewfstate would be easier for us now,but I can also see how that would besignificantly more challenging.DB: Since Namasté Solar is a 100%employee-owned business and youmake major decisions based on consensus,I’m curious what health careplan you arrived at as a group. Healthinsurance is a major expense for smallbusinesses, but it’s also an importantbenefit for employees. When 55co-owners weigh the benefits and thecosts, what does the plan look like?BJ: With any contractor business,one of the biggest expenses iscompensation and that includeshealth insurance. At Namasté, we geta choice between a health savingsaccount and a preferred provider organization.Everybody can find the righthealth insurance plan to meet theirfamily’s needs.In general, what you get with ourdecentralized ownership structure—we don’t really have some people withmore control than others—is you geteverybody thinking and acting likeowners. We all take ownership for thepolicies, for the decisions, for the qualityof work that we do.Small-business challenges canbe exacerbated by really fast growth.We’ve had our share of growing pains,but I think we’ve been able to tacklethem better because everybody at ourcompany is thinking and acting likean owner. We benefit from 55 uniqueperspectives to find the optimal solution.Compared to a contractor that isone sole proprietor and 54 employees,American Recovery and Reinvestment Act BlakeJones and the co-owners of Namasté Solar wereselected to participate in the signing ceremony for thehistoric stimulus act on February 17, 2009.we have 55 times the entrepreneurialenergy. That resource has allowed usto come up with some amazing solutionsto small-business challenges.Small-business challenges can be exacerbated byreally fast growth. We’ve had our share of growingpains, but I think we’ve been able to tackle thembetter because everybody at our company is thinkingand acting like an owner.Courtesy namastesolar.comDB: What percentage of Namasté Solar’sinstalled PV capacity is commercial versusresidential? Have you identified one ofthese particular markets as your dominantgrowth vehicle?BJ: We want the balanced approach. Itis interesting to see models out thereof companies just focusing on commercialor just focusing on residential.We really like focusing on both. We’renot focusing on multi-megawatt,utility scale solar installations. We’rereally focusing on DG or customersitedsolar.Part of our reasoning for the balancedapproach is diversification.You’ve seen incentives favor commercialprojects, bothat the federal and statelevels. At other times you’veseen projects or even theeconomy favor residential.Another part of it is logistics,planning. When youhave a few big commercialprojects, there’s a spike inperson-power requirements.If you’re doing only commercialprojects, I think itwould be very, very difficultto mobilize and demobilizepeople. You’d have to scheduleprojects so they’re backto back to back. If you haveresidential projects, you cansalt-and-pepper them inbetween big commercial projects.Right now I think we’re balanced,approximately half residential andhalf commercial. Back last October orNovember, commercial projects weredead in the water because they werehardest hit by the capital marketsbeing frozen, whereas our residentialprojects were still going full steamahead. The state incentive programhas also favored one or the other fromtime to time. So it’s hard to have astrategy that focuses on commercialor residential when things are sodynamic. You have to be adaptableto changing market conditions andpolicy environments.DB: Looking at your Web site, I noticedthat co-founder Ray Tuomey has anextensive marketing background. Howhas that helped Namasté Solar grow andsucceed in a very competitive market?BJ: Ray has a long background in ourcommunity; he knows everyone. Yougo out to lunch with Ray, chances arethere will be four or five people whogo, “Hey, Ray, how you doing?” Youcan’t underestimate the value of someonelike Ray who’s a good networker,who’s been doing business in yourmarket and your c o n t i n u e d o n p a g e 8 986 SolarPro | October/November 2009

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community for a long period of time,who really understands relationshipbuilding.Plus, Ray understood marketingand PR better than I did. Advicegiven to someone starting a companyis to partner with people who havecomplementary strengths and weaknesses.That was definitely the casein our situation.DB: Are there marketing and PR strategiesthat seem to work the best for you?Does Namasté Solar dedicate a lot ofresources to marketing and PR?BJ: We don’t. We do things a little bitdifferently than most solar companies.Our conventional advertising andpromotional budgets are really small.We prefer to promote ourselves via ourco-owners. We love attending fairs andfestivals, for example, as most solarcompanies do. But that’s not the onlyplace where we get to interact with thecommunity. We spend thousands ofhours doing educational outreach forfree each year. We actually have a fulltimeposition dedicated to communityand educational outreach.We also have an innovative grantprogram. We donate 1% of our revenuesin the form of solar systems to communitynonprofits. Instead of giving them$5,000 or $10,000 that will help themthis year, we’re giving them a solar systemthat will decrease their operatingbudget by thousands of dollars everyyear, for the next 30 years or more.This does multiple things. Not onlydoes it increase awareness about solar;not only does it free up importantresources for the nonprofits so theycan accomplish their missions; but it’salso a way for the constituents, membersor supporters of the nonprofitto learn about our company. Manycompanies have corporate responsibilityprograms or give charitable donationsas a way of getting their nameout in a positive way. We’ve definitelyfound in some ways our grant programcan double as a form of advertisingand promotion. Although that’s not theprimary intention, it ends up being oneof the fringe benefits. We would rathergive 1% of our revenue away in theform of solar systems for communitynonprofits, with that advertising benefiton the side, than spend 1% straightup on conventional advertising.Rather than increasing our advertisingbudget, we emphasize qualityinstallations and customer satisfaction.Both activities can increase leadsand sales. But we prefer the betterquality, better customer service route.We think referral leads are better thanadvertising leads; the sales conversionrates are better.Sunny PRO Club | A Professional PartnershipBuild your business by joining forces with SMA.With unprecedented growth projected in the renewable energyindustry, competition is getting fi erce. Are you ready?Join the Sunny PRO Club and give your business the edge itneeds by teaming with the marketing power of SMA.Your expertise, our resources: the perfect partnership. Join today.Visit www.SunnyPROClub.com to apply.Members can receive...» Customized Marketing Materials» Free Annual Training» Online Solar Professional Listing» SMA Sales Leads» Priority Technical ServiceFor more informationcall 888.476.2872SPCBUILDBUSIN-AUS090515solarprofessional.com | SolarPro 89

TrainingContinuingEducation for the ProARIZONAPV Installer TrainingSunWize TechnologiesNov 3 – Nov 4Phoenix, AZsunwize.comCAliforniASolar PV Boot CampBoots on the RoofNov 2 – Nov 7Fremont, CA$3,195N-EL/N-TP:PV/Nbootsontheroof.comSolar PV Boot CampBoots on the RoofNov 16 – Nov 21Fremont, CA$3,195N-EL/N-TP:PV/Nbootsontheroof.comSolar PV Boot CampBoots on the RoofNov 30 – Dec 5Fremont, CA$3,195N-EL/N-TP:PV/Nbootsontheroof.comPV System Design forEngineers & DesignersHigh Sun EngineeringDec 7 – Dec 9San Francisco, CA$985N-CEsunengineer.comSolar Thermal Boot CampBoots on the RoofDec 7 – Dec 11Fremont, CA$2,495N-EL/N-TP:PV/Nbootsontheroof.comSolar PV Boot CampBoots on the RoofDec 14 – Dec 19Fremont, CA$3,195N-EL/N-TP:PV/Nbootsontheroof.comSolar PV for SalesProfessionalsBoots on the RoofJan 11 – Jan 14Fremont, CA$2,395N-EL/N-TP:PV/Nbootsontheroof.comSolar PV Boot CampBoots on the RoofJan 18 – Jan 23Fremont, CA$3,195N-EL/N-TP:PV/Nbootsontheroof.comSolar Thermal Boot CampBoots on the RoofJan 25 – Jan 29Fremont, CA$2,495N-EL/N-TP:PV/Nbootsontheroof.comSolar PV Installer/DesignerSales & Estimator I, II, IIIGreen Career Instituteclasses weeklyOakland and Ontario, CA$299/$149Ngreencollarschool.comCOLORADOSolar Thermal & Hot WaterSystems for InstallersColorado Mountain CollegeOct 3 – Oct 10Rifle, CO$300N-ELcoloradomtn.eduDELAWAREThe Business of Solar PVIEC ChesapeakeNov 18Wilmington, DE$125N-ELiec-chesapeake.comFLORIDAPV Installer TrainingSunWize TechnologiesDec 8 – Dec 9Tampa Bay, FLsunwize.comHAWAIIGrid-Tied PV DesignSolar Energy InternationalNov 9 – Nov 13Honolulu, HI$895ISPQ/N-TP:PVsolarenergy.orgAdvance PV: Design Criteria& NEC ComplianceSolar Energy InternationalNov 16 – Nov 20Honolulu, HI$995ISPQ/N-TP:PVsolarenergy.orgMARYLANDPV Systems & the NECwith John WilesIEC ChesapeakeNov 4Elkridge, MD$100N-ELiec-chesapeake.comThe Business of Solar PVIEC ChesapeakeNov 17Elkridge, MD$150N-ELiec-chesapeake.comNORTH CAROLINAGrid-Tied PV DesignSolar Energy InternationalDec 7 – Dec 11Raleigh, NC$895ISPQ/N-EL/N-TP:PVsolarenergy.orgNew JerseySolar PV Boot CampBoots on the RoofNov 9 – Nov 14Newark, NJ$3,195N-EL/N-TP:PV/Nbootsontheroof.comSolar PV for SalesProfessionalsBoots on the RoofNov 16 – Nov 19Newark, NJ$2,395N-EL/N-TP:PV/Nbootsontheroof.comSolar PV Boot CampBoots on the RoofDec 1 – Dec 12Newark, NJ$3,195N-EL/N-TP:PV/Nbootsontheroof.comSolar PV Boot CampBoots on the RoofJan 25 – Jan 30Newark, NJ$3,195N-EL/N-TP:PV/Nbootsontheroof.comPENNSYLVANIAPV Systems & the NECwith John WilesIEC ChesapeakeNov 5Newtown, PA$100N-ELiec-chesapeake.comTEXASPV System Design &InstallationImagineSolarNov 9 – Nov 13Austin, TX$1,295ISPQ/N/N-ELimaginesolar.comPV System Design &InstallationImagineSolarDec 7 – Dec 11Austin, TX$1,295ISPQ/N/N-ELimaginesolar.comPV System Design &InstallationImagineSolarJan 18 – Jan 22Austin, TX$1,295ISPQ/N/N-ELimaginesolar.comTraining accreditation keyISPQ Institute of Sustainable Power Quality program or providerN-ELN-TP:PVN-TP:STN-CENNABCEP PV Entry Level Certificate of Knowledge approved providerONLINENABCEP Board recognized training provider for PV installer exam qualificationPV Design ONLINESolar Energy InternationalNov 2 – Dec 13ONLINE$795ISPQ/N-ELsolarenergy.orgAdvanced PV ONLINESolar Energy InternationalNov 2 – Dec 13ONLINE$795ISPQ/N-ELsolarenergy.orgWebinar: RE Micro GridSEPA (Satcon, SunPower, FLSolar Center)Nov 12ONLINEfree to members or $125regonline.com/sepawebinarsWebinar: Satcon’s SolsticeSatconNov 17ONLINEfreesatcon.comPV InstallerStep Up EducationAnytimeONLINE$1,795solarclassesonline.comNABCEP Board recognized training provider for solar thermal installer exam qualificationNABCEP continuing education credit providerInstructor holds NABCEP installer certificationRE Career TrainingAllied SchoolsAnytimeONLINE$188 – $688 per courseN-EL/N-TP:PVtraining4green.comPost professionaltrainings online at:solarprofessional.com/training90 SolarPro | October/November 2009

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Projects SystemProfilesCOMMERCIAL GRID-DIRECT PHOTOVOLTAIC SYSTEM:Pearl Brewery, Full Goods BuildingOverviewDESIGNER: Tommy Jacoby, VPof design, Meridian Solar,meridiansolar.comPROJECT MANAGER: JasonComstock, Meridian SolarDATE COMMISSIONED: March 2009INSTALLATION TIMEFRAME: 10 weeksLOCATION: San Antonio, TX, 29.5°NSOLAR RESOURCE: 5.4 kWh/m 2 /dayRECORD LOW/AVERAGE HIGH TEM-PERATURE: 0°F / 95°FARRAY CAPACITY: 200.6 kWAVERAGE ANNUAL AC PRODUCTION:267 MWhEquipment SpecificationsMODULES, FLAT ROOF: 608 SCHOTTSolar ASE 300 DGF/50, 300 W STC,+4%/−4%, 5.9 Imp, 50.6 Vmp, 6.5 Isc,63.2 VocMODULES, AWNINGS: 96 Sanyo HIP-190DA3, 190 W STC, +10%/-0%, 3.44Imp, 55.3 Vmp, 3.7 Isc, 68.1 VocINVERTERS: 3-phase, 208 Vac service,four SMA ST42 (SunnyTower),42 kW each, six SB7000US per tower,600 Vdc maximum input, 250–480Vdc MPPT range; one additional SMASB6000US, 6 kW, 600 Vdc maximuminput, 250-480 Vdc MPPT rangeIn April 2001, when the Pearl Brewery inSan Antonio, Texas, shuttered its doorsafter 118 years of operation, many consideredthe buildings on the 22-acre sitea prime target for demolition. Instead,the historic landmark was saved thanksto the vision of investor Silver Venturesand the site’s proximity to a planned1.3-mile extension of the famous SanAntonio River Walk. Providing a terminusfor tourist barges, the renovatedPearl Brewery complex anchors thesustainably built urban revitalizationproject known as Rio Perla. At the heartof the project is the Full Goods Building,a former beer distribution warehouseredeveloped as mixed-use office, retail,restaurant and residential space. Renovatedto LEED standards, the Full GoodsBuilding is home to a 200 kW gridconnectedPV array, the largest privatelyowned PV system in Texas.Designed by Meridian Solar, thebulk of the PV generating capacity—182 kW—is installed on a new TPOmembrane roof using SCHOTT Solar ASE300 W modules and the manufacturer’sproprietary SunRoof FS mounting system.TPO-compatible slipsheet materialis installed under each array base plate.The locations and types of rooftop equipmentand skylights changed over time orwere not built as specified. This necessitatedmultiple engineering reviews toensure that ballast and setback requirementswere met and the manufacturer’swarranty remained intact.An additional 18 kW of PV areinstalled as shade canopies at the building’smain and service entrances. MeridianSolar worked closely with architectLake|Flato to custom design canopiesusing standard metal I-beams or trusses,ProSolar SolarWedge hardware and Sanyobifacial 190 W HIT Double modules. AUL-listed polypropylene film separatesthe aluminum mounting baseplate fromthe building’s structural steel to preventgalvanic corrosion associated with thecontact of dissimilar metals.Due to space constraints, the invertersare located on the roof, installed on aCourtesy meridiansolar.com (4)92 Solarpro | October/November 2009

custom elevated steel platform. SMASunnyTowers simplify transportationto the roof but were primarily specifiedto facilitate the use of multiple moduletechnologies. Within the SMA ST42, eachinverter operates independently; this allowsthe Sanyo and SCHOTT modules to bewired to separate inverters on the sametower. CPS Energy, the municipal utility,required that Meridian Solar tighten thevoltage trip points on each inverter, whichwas unexpected since smaller PV systemsin its service territory interconnect usingunmodified inverters.CPS Energy provided partial fundingfor the PV system at the Full Goods Buildingand intends to study system performance.Therefore, the data acquisition solutionprovided by Draker Laboratories includesweather sensors and performance analytics.In addition, the high profile installationfacilitates public outreach and education bymeans of an interactive kiosk with a largescreendisplay located in the Full GoodsBuilding lobby. Information about the PVsystem at the Pearl Brewery, including aninstallation video, is available online atpearl.kiosk-view.com.“When the utility told us to tighten voltagesettings in the inverters, we complied—thoughwe advised otherwise. After they saw theinverters nuisance tripping due to their owngrid signature, they gave us permission torestore the factory settings. This not onlyproved our expertise, but also our commitmentto customer service.”—Andrew McCalla, CEO,Meridian SolarEquipment Specificationsc o n t i n u e dARRAY, FLAT ROOF: Twenty 28module subarrays with sevenmodules per string (2,100 W, 5.9Imp, 354.2 Vmp, 6.5 Isc, 442.4 Voc)and four circuits per inverter (8,400W, 23.6 Imp, 354.2 Vmp, 26.0 Isc,442.4 Voc); two 24 module subarrayswith eight modules per string(2,400 W, 5.9 Imp, 404.8 Vmp, 6.5Isc, 505.6 Voc) and three circuitsper inverter (7,200 W, 17.7 Imp,404.8 Vmp, 19.5 Isc, 505.6 Voc)ARRAY, AWNINGS: One 36 modulesubarray with six modules perstring (1,140 W, 3.44 Imp, 331.8Vmp, 3.7 Isc, 408.6 Voc) and sixcircuits per inverter (6,840 W, 20.6Imp, 331.8 Vmp, 22.2 Isc, 408.6Voc); two 30 module subarrayswith six modules per string andfive circuits per inverter (5,700 W,17.2 Imp, 331.8 Vmp, 18.5 Isc,408.6 Voc)ARRAY COMBINER: Inverterintegrated with 15 A fusesARRAY INSTALLATION, FLATROOF: SCHOTT Solar’s selfballastedSunRoof FS mountingsystem on TPO membrane, 190°azimuth, 5° tiltARRAY INSTALLATION, AWNINGS:Professional Solar Products(ProSolar) SolarWedge hardwarestructurally attached to metalI-beams at main building entrance(10° tilt) and metal trusses atservice entrance (15° tilt),190° azimuthSYSTEM MONITORING: DrakerLaboratories Sentalis 1000PVmonitoring package with publickiosk; utility installed revenuegradePV metersolarprofessional.com | SolarPro 93

OCTOBER 27-29ANAHEIMCALIFORNIANORTH AMERICA’SLARgESTB2B SOLAREvENT“The Solar Power International conference and expo is by far the biggest and bestin the United States. And the prospects for solar energy have never been brighter.”— CAlIfornIA Governor Arnold SChwArzeneGGer650+ exhibitors featuring the latest inphotovoltaics, solar heating and coolingand concentrating solar technologies65+ education sessions featuring200+ speakers focused on technology,markets, policy and finance25,000+ solar industry experts from90+ countries gather to networkand drive the future of solar energyRegister now at SolarPowerInternational.com!PRESENTED BY:

Advertiser IndexCompanyPageAEE Solar 9Allied Moulded Products 88Blue Oak PV Products 73Buderus / Bosch Thermotechnology 65BP Solar 83Centrosolar America 37Conergy 15DC Power Systems 13DEGERenergie 81DEHN 91DH Solar 49Direct Power and Water 78Draker Laboratories 87EasyFlex 57Element Solar 79Enphase Energy 1ET Solar 55Flat Jack Solar Mount 53Fronius USA 23Company Page Company PagegroSolar 4 SMA America 5, 7, 89Heliodyne 63 Solar DepotIBCKaco Solar 27 Solar Energy International 85Lumos Solar 12 SolarMagic 25Lyon Financial 91 Solar Power International 94Magnum Energy 19 SolarBOS 67Meca Solar 69 SolarEdge Technologies 88Mitsubishi Electric 51 SolarWorld CaliforniaBCNABCEP 95 Solectria Renewables 33Ningbo Solar 41 Stiebel Eltron 61ONTILITY 75 SUNOWE Photovoltaic 47OutBack Power Systems 10-11 SunWize Technologies 77Phocos USA 91 Trina Solar 29Power-One 21 Trojan Battery 17PVselect.com 91 UniRac 43REC Group 2-3 Zep Solar 39S-5! 16 Zomeworks 88Satcon Technology CorporationIFCSCHOTT Solar 31Get THE Distinguished Mark forRenewable Energy ProfessionalsFind out how to become aCERTIFIED INSTALLER –visit our brand new website:www.nabcep.orgSince 2003, the North American Board of Certified Energy Practitioners(NABCEP) has been awarding professional credentials to renewableenergy installers. NABCEP’srigorous competency standardsfor certification send a clearmessage to consumers, installers,investors, and public officials that the industry stresses high quality,safe and ethical business practices, and strong workmanship standards.NABCEP Solar PV orSolar Thermal Certification800-654-0021solarprofessional.com | SolarPro 95

ProjectsRESIDENTIAL GRID-DIRECT PHOTOVOLTAIC SYSTEM:Habitat for HeroesOverviewDESIGNERS: Patra Ngaotheppitak,solar design engineer, and DavidBaker, mechanical engineeringmanager for research and development,Akeena Solar, akeena.comLEAD INSTALLER: Tom Spangler, fieldsuperintendent, Community ActionPartnership of Orange County,capoc.orgDATE COMMISSIONED: August 2009INSTALLATION TIMEFRAME: Fourhomes per dayLOCATION: San Juan Capistrano, CA,33.5°NSOLAR RESOURCE: 5.7 kWh/m 2 /dayRECORD LOW/AVERAGE HIGHTEMPERATURE: 21°F / 79°FARRAY CAPACITY: 1.4 kWAVERAGE ANNUAL AC PRODUCTION:2,075 kWhEquipment SpecificationsMODULES: Eight Andalay ST175-1,175 W STC, +3%/−3%, 4.95 Imp,35.2 Vmp, 5.2 Isc, 44.2 VocINVERTERS: Eight EnphaseM190-72-240-S12, 190 W, 54 Vdcmaximum input, 22–40 Vdc MPPTrange, single-phase, 240 Vac outputARRAY: Eight inverters per branchcircuitARRAY INSTALLATION: Roof mounton flat tile roof, Andalay flat tilemounts, 213° azimuth, 22° tiltSYSTEM MONITORING: EnphaseEnlighten online monitoring, revenuegradekWh meterDo you have a recent PVor thermal project we shouldconsider for publication inSolarPro?Visit: solarprofessional.com/projectsHabitat for Heroes is a 27-unit housingdevelopment for low income familiesand veterans being built by Habitat forHumanity of Orange County, California.Each of the homes has a 1.4 kW grid-tiedPV system aimed at reducing the homeowner’selectricity bills by up to 70%. Apublic/private partnership—consisting ofAkeena Solar, Morgan Stanley Solar Solutionsand the Community Action Partnershipof Orange County (CAPOC) fundedthrough the state of California—wasformed to provide the PV systems.Workers with no previous solarexperience are involved in the project,including CAPOC weatherization fieldcrews, the Orange County ConservationYouth Corps and Habitat forHumanity volunteers, so easeof installation and simplicityof design are a must. AkeenaSolar’s Andalay AC panel systemis an ideal solution.Each Andalay AC solar panelhas an integrated Enphase microinverter.The ac output of groupsof eight panels forms a dedicatedbranch circuit. A flashed, roofmount SolaDeck junction box—apart in RSTC Enterprises’ Commdeckproduct line (rstcenterprises.com)—isused to transitionconductors off the roof. The acwiring is run through interior walls, likeany other branch circuit, and interconnectsvia a 15 A circuit breaker.Time on the roof is minimized dueto Andalay’s frame-integrated mountingsystem. No additional racking isrequired. Flashed standoffs ensure thatthe tile roof remains watertight.“We created four working groups using25 crew members from three differentcompanies—all of whom were new tosolar—and installed four systems in oneday. Participants were able to build off theirtrade experience and quickly learned howto install these panels.”—Tom Spangler, CAPOC fieldsuperintendentCourtesy Robert Rooks Photography (RRphoto.net)Courtesy akeena.com96 Solarpro | October/November 2009

LOOKING FOR ADISTRIBUTOR THAT WON’TCOMPETE WITH YOU?Solar Depot is exclusively focused on serving its dealer network and providing themwith all the products and services they need to be successful.Our business is to support our customers, not compete with them.GET THE SOLAR DEPOT ADVANTAGEPre-engineered Packaged Systems Superior Technical SupportRebate Filing AssistanceJobsite DeliveryProduct Shipment NationwideMarketing & Advertising SupportSOLAR PV / SOLAR WATER HEATING / SOLAR POOL / RADIANT FLOOR HEATINGSOLAR DEPOT BRANCHES:Northern CA: Central CA: Southern CA: NEW! Florida:Petaluma, CA Sacramento, CA Corona, CA St. Augustine, FL1-800-822-4041 1-800-321-0101 1-800-680-7922 1-904-827-9733BOOTH #521Your One-Stop Shop for All of Your Solar NeedsWholesale Distributor / System Integrator Since 1979www.solardepot.comSOLAR DEPOT

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October/November 2009New PTC Module Ratings | Article 690.31(A) ComplianceOptimal Design, Installation & Performancesolarprofessional.comPhotovoltaic SystemMicroinverterMarket ShareEnphase Establishesan Application NicheCommissioningSolar ThermalCollectorsNavigating SRCC Dataand RatingsPV EquipmentTrendsSolar Power InternationalProduct PreviewInterview:Blake JonesNamasté SolarBusiness Perspectivesfrom a Leading IntegratorSun Light & PowerBerkeley Bowl West MarketplaceBerkeley, CA findustry professionalsSUBSCRIBE FOR FREEsolarprofessional.com

SatconUtility Ready SolarThe Most Widely Used Utility Scale Solar Inverters On the Market TodayHundreds of Millions of Grid Connected kWh Delivered• Proven in the World’s LargestSolar Installations• Simplified Grid Interconnection• Unparalleled Efficiency &Performance• Remote Command & Control1 Megawatt PowerGate® PlusFor over 24 years Satcon has set the standard for large scale advanced powerelectronics. Our utility ready solutions have delivered more kWh to the gridthan any large scale solar PV solution on the market today, with over 160megawatts of our PowerGate® 500 kW units installed in the field since 2006.Call 888-728-2664or visitwww.satcon.comto learn moreSuccessful large scale solar PV requires grid proven technologies. Contactyour local Satcon consultant today and develop the most profitable largescale power plants in the world.©2009 Satcon Technology Corporation. All rights reserved. Satcon is aregistered trademark of Satcon Technology Corporation.