SOLAR TODAY - May 2011 - Innovative Design

SunShot Boosts NREL’s
Incubator Program
Not all SunShot funding went toward
the projects at 1366 Technologies,
3M, PPG, Varian Semiconductor and
Veeco, a fifth recipient. Another $7 million
was injected into the National Renewable
Energy Lab’s Photovoltaic (PV) Technology
Incubator program.
Started in 2009, the incubator program
is primarily tasked with hastening
nascent PV technologies’ transition from
the drawing board into the lab. There
are two funding tiers: The first supports
the development of commercially viable
prototypes; the second helps companies
scale up to the pilot-project manufacturing
stage. The latest funding targeted the
four companies below.
Tier One
Caelux — $1 million
Caelux of Pasadena, Calif., is developing
a flexible PV-manufacturing process that
minimizes the amount of semiconducting
material used.
Solexant — $1 million
Solexant of San Jose, Calif., is developing
a new printable nanoparticle thin-film ink
from common nontoxic substances.
Stion — $1 million
Stion of San Jose, Calif., is developing a
technology consisting of two stacked
high-efficiency thin-film devices, offering
improved absorption of light.
Tier Two
Crystal Solar — $4 million
Crystal Solar of Santa Clara, Calif., is commercializing
single-crystal silicon wafers,
four times thinner than standard cells.
Arnie Funkenbusch and Tracie Berniard, of 3M’s renewable energy division, with a roll of 3M Ultra Barrier
Solar Film. The Maplewood, Minn.-based company was awarded $4.4 million in SunShot funding to scale
up manufacturing of the film in February.
able Energy Laboratory (NREL). Using feedback
from NREL and the CIGS module manufacturers,
Funkenbusch expects the redesign to have
increased light transmission, better durability and
lower cost. “What we want to do is make sure we
have a product that lasts 25 years,” Funkenbusch
says. “That’s where SunShot helps us out.”
The new manufacturing line will go in at an
existing 3M factory in Columbus, Mo. According
to the Columbus Daily Tribune, the line will
add 120 jobs to a plant that’s shed jobs for years.
Construction of the line is underway and production
is set to begin in early 2012. There are
indications that CIGS module manufacturer
SoloPower, which recently secured a $197 million
DOE loan guarantee for a new factory in
Wilsonville, Ore., will be the first customer.
Varian Semiconductor
Target: IBC Cell Production, Expense
Recent NREL tests have measured SunPower’s
interdigitated-back-contact solar (IBC) cells
at the highest conversion efficiencies to date. The
principle is very simple: IBC cells eliminate frontside
metallic conductors, which typically cover 5
to 8 percent of the physical surface of a wafer.
Move the wiring to the backside, more sunlight
gets absorbed, and cell efficiency spikes.
The only factor preventing IBC PV from
becoming the industry standard is cost.
“Currently, IBC solar has the highest efficiencies,
but it’s very expensive to make,” says
Jim Mullin, general manager for solar products
at Varian Semiconductor (vsea.com). “In solar
manufacturing, every step adds cost, adds complexity,
and can result in potential yield loss.” In
Gloucester, Mass., Mullin and his associates at
Varian are using $4.8 million in SunShot funding
to develop an ion-implant tool that promises to
slash the number of manufacturing steps from
21, necessary in the conventional IBC process
today, to eight.
Ion implantation is far from a novel concept
— implanters are integral to semiconductor
device fabrication and have long been used
to make computer chips. Varian’s been selling
the tools to the electronics industry since 1975
and has an ion implanter, the Varion Solion, for
conventional PV cells that’s already running in
high-volume production. SunShot backing will
be used to redesign the Solion to give it the capability
to do backside wafer patterning necessary
for IBC cell production. No manufacturer has
attempted it. “We’re the first ones to do this,”
Mullin says. “We are in a unique position because
we’re the only ones that can really do it without
impacting the tool’s productivity — because we
own the intellectual property.”
Mullin says that Varian has matched its DOE
funding with internal investments well north of
$20 million. He expects the tool to be commercially
ready within three years.
It’s unclear how much the reduction in production
complexity will reduce IBC costs. Module
manufacturers have some ground to make
up before IBC solar is cost-competitive with
other PV technologies. San Jose, Calif.-based
SunPower is the only company commercially
producing IBC modules today and is operating
at a production cost of around $1.70 per watt.
Chinese crystalline-silicon manufacturers are
producing at about $1.20 per watt, while First
Solar, a CdTe thin-film manufacturer, is now
down below the $0.75 mark. ST
3M
Copyright © 2011 by the American Solar Energy Society Inc. All rights reserved.
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