Friday, June 23, 2006

Large-Scale, Cheap Solar Electricity

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

By Kevin Bullis

Part of a solar-cell printing machine in Nanosolar’s pilot manufacturing plant. The technology might make solar power competitive with electricity from the grid. (Courtesy of Nanosolar.)

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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.