innovators | ken Zweibel
last October, when General Electric began mov- ing its PrimeStar solar-module manufacturing division into what will soon be a 400-megawatt- capacity plant in Aurora, Colo., Ken Zweibel had a good reason to feel satisfied. For three decades, he
had nursed cadmium-telluride research along at the Solar
Energy Research Institute (SERI) and then the National
Renewable Energy Laboratory (NREL), until it could stand
on its feet as a profitable commercial technology.
When Zweibel got his Bachelor of Science degree in
physics at the University of Chicago in 1970, he didn’t
expect to do science research. Instead, he wanted to write
fiction. For most of a decade he tried to sell novels and
mystery stories, but what paid
the rent was technical writing
and editing. And so, in 1979,
he joined SERI as a full-time
technical editor.
A couple of years later,
Zweibel teamed up with
colleague Paul Hersch to
write “Basic Photovoltaic
“We started out with programs in polycrystalline silicon,
thin-film copper indium selenide (CIS), cadmium sulfide/
copper sulfide (CdS/Cu2S) and some in cadmium telluride
(Cd Te),” Zweibel recalled. “We had three or four million
dollars in annual funding, and mostly supported Boeing’s
CIGS (copper indium gallium selenide) and Ting Chu’s
low-cost substrate programs at Southern Methodist University. Chu went on to be the most important person in
cadmium telluride from the 1980s onward because he catalyzed progress in thin-film efficiency from 10 percent to 15
a technical
Writer Leads
a thin-Film
Revolution
by SETH MASIA
JESSIcA mccONNEll bUr T/ THE GEOrGE WASHING TON UNIvErSITy
14 March/April 2012 SOLAR TODAY solartoday.org
Seth masia is an editor of
SOLAR TODA Y and director
of communications at the
American Solar Energy
Society. Contact him at
smasia@solartoday.org.
Copyright © 2012 by the American Solar Energy Society Inc. All rights reserved.
percent — his cadmium-telluride cell of 1992 was the first
15 percent thin-film cell of any kind, before CIS, and it got
others to jump into the commercialization of Cd Te. One
of the first things I was asked to do was to cancel a major
copper-sulfide program at the University of Delaware. Cop-
per sulfide had a stability problem and CIS was viewed as
the solution, but I still wonder if copper sulfide would have
made a major impact. John Meakin was a pioneer there.”
Zweibel notes that the 1980s were a heyday for amor-
phous silicon research. “Cd Te thin film was the stepsister
of the SERI program, constantly threatened with cancel-
lation,” he said. “It took a lot of effort to keep it going.”
Researchers didn’t like cadmium, a poisonous heavy metal
that had potential to be an environmental hazard. “There
was a sense that we could do this technology without the
cadmium, so CdTe got half the money that CIS did. But
Cd Te performed very well.”
When Allen Hermann left SERI to do research in
superconducting compounds at the University of Colora-
do-Boulder, Zweibel took over management of the thin-
film programs.
By 1995 it had become clear that amorphous silicon was
never going to outperform the other thin films. The multiple
programs were therefore consolidated into a single department, the Thin Film Partnership, with Zweibel as director.
The goal was to move thin-film technologies rapidly into
mass production.
“We had a good relationship with internal NREL
research and external research at universities and start-up
companies,” Zweibel said. Among the external partners was
glass manufacturer Harold McMaster, who abandoned his
Glasstech Solar amorphous silicon project and, at the urging of his production chief Jim Nolan, launched Solar Cells
Inc. to commercialize Cd Te. That enterprise evolved by
1999 into First Solar. In El Paso, Texas, John Jordan coated
Cd Te onto glass and built Photon Power, later selling the
company to ACX, owned by the Adolph Coors family in
Golden, Colo. Matsushita entered the market. Efficiency
crept up to 11 percent. British Petroleum (BP) opened a
Cd Te plant in Fairfield, Calif., and then, in a move that seriously damaged the investment climate for thin film, closed
it after four years, in favor of monocrystalline silicon.
After the BP setback, the U.S. Department of Energy
(DOE) reevaluated its solar programs and, for fiscal year
2001, launched NREL’s Solar America Initiative. As much
as $90 million was available annually to support deployment of solar technology — most of it earmarked for photovoltaics. Solar America continued the traditions of the
Thin Film Partnership and the PV Manufacturing Initiative,
which were absorbed into it.
Early in 2006, Zweibel, Bryan Murphy, Fred Seymour, Jack Little, Russell Black, Joe Beach and Mark
Auble set up PrimeStar Solar, with the goal of adapting flat-screen display production techniques to thin-film solar production. With the help of Mark Waller at
