INTRODUCTORY SPECIAL INTRODUCTORY ... - PHOTON Info

How a microinverter works
Varistors (variable resistors),
voltage – dependent, resistors
to prevent overvoltage
Connector (AC input), can be used to
connect several microinverters in parallel.
Chokes and capacitors (blue) serve as filters,
to keep grid disturbances form interfering
with the inverter, and vice versa.
ers. Their 150 W product, available for
purchase in the EU only, was released
in 1995. Interestingly enough, Dorfmüller’s
products have been on the market
since 1995 with just 2 to 5 year warranties,
effi ciencies of 89 to 92 percent, and
no sophisticated monitoring system. The
company’s owner, Joachim Dorfmüller,
says the products have been used in
a variety of different sized installations,
but admits that demand has never been
stronger than this year. In 2008 he sold
3 MW, says Dorfmüller, and this year he
sold 4 MW. He would have sold more, if
he had been able to keep up with the fl ood
of orders. Next year, he says, he expects
to sell 10 MW. And Dorfmüller hopes to
test the US market soon, too, since that’s
where all the action seems to be.
Where is the market?
In truth, fi nding the right market – or
rather, market niche – is a challenge new
start-ups are still sorting out. Enphase is
cozying up with everyone from Suntech,
Transistors break up the current from the capacitors into different
length pulses - a preliminary step toward the 60Hz-frequency
sine waves that synchronize with the grid.
AC output Cable
Coils smooth the alternating current
coming from the transistors into a clean
sine wave form.
DC input - the module
is hooked up to the inverter
with a traditional solar connector.
who sells Enphase’s inverters along with
its modules, to several start-ups building
DIY kits ultimately destined for retail. The
advantages vary according to system size.
One of the fi rst companies to search
for a microinverter niche was Los Gatos,
California-based Akeena Solar, Inc., one
of the larger US installers. The company,
which offers a ready-to-install product
called Andalay to private customers
and other installers, has just completed
a two-year test phase with Enphase microinverters.
Now, the company is rolling
out an Andalay AC module. CEO
Barry Cinnamon says the microinverter
is a key development in making solar
power accessible to a wide market of residential
and small commercial installations.
Cinnamon says it has installed
thousands of Enphase microinverters,
and not one has failed.
Akeena is just one of a small herd of
companies chomping at the bit to increase
their market shares by narrowing
balance-of-systems costs. Solar Red,
Electrolytic capacitors for DC input: These store
DC power until the transistors call for it.
Because the energy that a capacitor can hold is a
factor of voltage and capacitance, microinverters with
low voltage input require high capacitance.
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Inc., Armageddon Energy, Inc., Ready
Solar Inc., and Veranda Solar Inc. are a
few early-stage companies developing
systems with built-in AC wiring and integrated
microinverters – systems that
require no string-sizing calculations and
can be purchased and built module by
module, or even snapped together all at
once as a full array. And each story echoes
the next: as module prices fall, bloated
balance-of-systems labor costs become a
larger proportion of total system costs.
Companies must compete to offer better,
simpler installations.
Enphase and other microinverter
manufacturers are promising signifi cant
benefi ts for non-integrated systems too.
Much like companies that build poweroptimizer
systems for tracking each
module’s maximum power point – for
instance, National Semiconductor’s SolarMagic,
SolarEdge’s Power Box, and
Ehw Research’s Smart Power Box – these
micro-inverters claim to recover anywhere
between 5 and 25 percent of a
graphic: Udo Rohnke / PHOTON