Special Reports
Large-Scale, Cheap Solar Electricity

By Kevin Bullis
Technology Review
June 23, 2006

A well-financed California startup is promising to build
a solar-cell factory that could finally make solar power affordable.

This week, Nanosolar, a startup in Palo Alto, CA,
announced plans to build a production facility with the
capacity to make enough solar cells annually to generate
430 megawatts. This output would represent a substantial
portion of the worldwide production of solar energy.

According to Nanosolar's CEO Martin Roscheisen, the
company will be able to produce solar cells much less
expensively than is done with existing photovoltaics
because its new method allows for the mass-production of
the devices. In fact, maintains Roscheisen, the
company's technology will eventually make solar power
cost-competitive with electricity on the power grid.
Nanosolar also announced this week more than $100
million in funding from various sources, including
venture firms and government grants. The company was
founded in 2001 and first received seed money in 2003
from Google's founders Larry Page and Sergey Brin.
Experts say Nanosolar's ambitious plans for such a large
factory are surprising. "It's an extraordinary number,"
says Ken Zweibel, who heads up thin-film research at the
National Renewable Energy Laboratory in Golden, CO. Most
groups building new solar technologies "add maybe 25 or
50 megawatts," he says. "The biggest numbers are closer
to 100. So it's a huge number, and it's a huge number in
a new technology, so it's doubly unusual. All the
[photovoltaics] in the world is 1,700 megawatts."

Today, the lion's share of solar cells are based on
crystalline silicon, which is about three to five times
too costly to compete with grid electricity, Zweibel says.

Nanosolar's technology involves a thin film of copper,
indium, gallium, and selenium (CIGS) that absorbs
sunlight and converts it into electricity. The basic
technology has been around for decades, but it has
proven difficult to produce it reliably and cheaply.
Nanosolar has developed a way to make these cells using
a printing technology similar to the kind used to print
newspapers, rather than expensive vacuum-based methods.
Although the company expects to start selling solar
cells next year, ramping up to full production will take
more time. Meanwhile, high demand for solar cells
worldwide will keep prices high, Roscheisen says.
Eventually, however, he says the company hopes to
attract more customers with lower prices, in several
years reaching prices that make solar-power electricity
competitive with the grid.

Zweibel says the company is likely to face challenges in
ramping up production, although their pilot
manufacturing facility is a big step. And he adds that
Nanosolar is not alone in developing inexpensive
manufacturing processes for CIGS solar cells, and at
least one other company is working with a printing process.

Meanwhile, Andrew Gabor, senior engineer at Evergreen
Solar, a silicon solar-cell developer and manufacturer
in Marlboro, MA, says current supply problems related to
conventional solar cells are easing as more production
capacity is coming on line. This could mean that prices
for silicon cells start dropping again, eventually
becoming competitive with grid electricity. He suggests
that in the future solar electricity supply will likely
be met by a mix of technologies.


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