From: Reuters
Published April 2, 2008 01:00 PM

New solar CIGS cells creep up on silicon

By Matt Daily

NEW YORK (Reuters) - Silicon cells have been the mainstay of the solar photovoltaic industry, but advances in competing technologies could give those manufacturers a toehold in the rapidly growing renewable power market.

Last week, researchers at the U.S. Department of Energy's National Renewable Energy Laboratory said they had achieved a new efficiency record for one of those promising technologies, putting it within reach of the silicon cell mark.

The new technology uses copper indium gallium selenide, or CIGS, to turn sunlight into electricity inside a thin-film solar cell that is generally less expensive than versions relying on polysilicon.


CIGS technology converts 19.9 percent of the sunlight hitting the cell into power, beating the previous mark of 19.5 percent and nearing the multicrystaline silicon cell record of 20.3 percent.

Although the increase in efficiency looks modest, it would represent a 3 percent rise in production capacity for a company putting out one megawatt of electricity per year, said Ingrid Repins, a researcher on the NREL team. One megawatt can power about 850 homes.

Silicon-based solar cells held 94 percent of the global market in 2006, according NREL data, with the remaining 6 percent split among thin-film companies, including CIGS makers.

But that thin-film market share appears to be growing rapidly, helped by the opening of plants by companies such as First Solar, which uses different materials to construct its cells.

Just a few years ago, CIGS cells' efficiency stood near 15 percent, Repins said, and the technology is probably capable of reaching 23 percent in coming years.

Global Solar, a privately held company that licenses CIGS technology from the NREL, last month opened an Arizona plant that will be capable of producing 40 MW of thin-film solar cells per year, and it plans to open another in Germany later this year.

Other companies using CIGS technology include NanoSolar, which sparked market interest last year with its promise to make low-cost cells, as well as Ascent Solar Technologies, Miasole, International Solar Electric Technology Inc, SoloPower Inc and Solyndra.

Analysts do not expect many public offerings from the sector in the near-term because of market turmoil that has caused shares of even the largest solar companies to swing wildly.

Daystar, one of the only publicly listed CIGS makers, has seen its stock sink by about half this year to around $3.40 as it moves toward putting its production plant on line.


Natixis Bleichroeder analyst Mark Manley said the CIGS producers still needed to prove they could turn technological advances into viable products.

"What you can do in the lab is one thing, but what you do in commercial production is another," he said. "What matters ultimately in solar from the economic standpoint is how many kilowatt hours you can produce for your dollar."

Global Solar cells' efficiency is about 10 percent, or half the level NREL achieved on a small scale in the lab.

The company's long-range goal is to mass-produce cells with 15 percent efficiency, said Chief Technology Officer Jeff Britt.

"We have to develop manufacturing processes that are much faster ... and we have to coat many square meters (with the CIGS semiconducting material)," he said.

Under their nonexclusive pact, the NREL provides Global Solar with updates on its technological advances.

"In many cases, we're able to emulate the changes that they made in our own production," Britt said. "It's very helpful."

(Editing by Lisa Von Ahn)

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