San Jose's Nanosolar, a manufacturer of thin-film solar panels, said Wednesday that it has raised $300 million to help it complete production lines in Silicon Valley and in Germany. It's the largest amount of money raised by a solar start-up this year, and confirms that investors see the company's technology as ready for prime time.

"It's obviously a huge win for us," Martin Roscheisen, Nanosolar's chief executive, said in an e-mail from Europe.

The company, located in South San Jose's Edenvale clean-technology development district, uses copper indium gallium selenide (CIGS) rather than silicon for its solar panels. The promise of thin-film solar is that it will be much cheaper than traditional panels. Previously, Nanosolar talked about being the first company capable of profitably selling solar panels for 99 cents a watt.

Describing the investment as "one of the larger funding rounds we've seen in the solar energy marketplace," an industry observer noted that big dollars are flowing into solar now as the technology moves from the lab to the factory.

"Nanosolar has plenty of company in the photovoltaic and concentrating solar power start-up space," said Michael Bates, managing editor of Solar Industry magazine. "Companies such as HelioVolt, SolFocus and Suniva have all taken part in investment rounds exceeding $50 million."...