OptiSolar joins others in raising huge rounds for solar farms

Thin-film solar company OptiSolar raised another $20 million from investors, according to a regulatory filing, topping its Series B-1 at $97 million, and bringing its year-to-date total to $229 million.

The company previously raised $132 million in April from Richardson Capital and an undisclosed venture firm.

The company did not respond to a request for comment, but the money may be going to help finance, among other projects, a 550-megawatt solar farm in San Luis Obispo, Calif., that is expected to power about 190,000 homes when it is completed in 2010.

Hayward, Calif.-based OptiSolar is one of a handful of young companies to raise mega-financing rounds recently to build out solar power plants.

Last month, Nanosolar announced it had raised $300 million. The majority of the funding came from The Carlyle Group, power company AES, Energy Capital Partners and French utility EDF. Other investors include GLG Partners, Beck Energy, Grazia Equity, the Skoll Foundation, Lone Pine Capital and individual investor Pierre Omidyar, founder of the Omidyar Network. Nanosolar intends to build a 430-megawatt plant in San Jose, Calif., and a 620-megawatt facility in Berlin.

SunEdison raised $131 million in equity and an additional $30 million in debt financing from HSH Norbank Kapital, Applied Ventures and Greylock Partners in May. The company is building a 21.5 megawatt photovoltaic farm that it boasts will be the largest solar installation worldwide when it is completed in 2009.

BrightSource Energy, which makes solar-thermal power plants, collected $115 million from new investors Google.org, BP Alternative Energy, StatoilHydro Venture and Black River in May. Return backers included VantagePoint Venture Partners, Morgan Stanley, DBL Investors, Draper Fisher Jurvetson and Chevron Technology Ventures.

BrightSource is looking to build five large solar-thermal plants in the Mojave Desert of Southern California, and the company has signed agreements to tentatively provide PG&E Corp. with 900 megawatts of energy a year once the plants are completed in 2011. —Alexander Haislip