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Thin-film solar maker Nanosolar was already one of the more well-funded startups in cleantech with at least $150 million behind it. But this morning Nanosolar’s CEO Martin Roscheisen writes on the company blog that Nanosolar has raised $300 million in an oversubscribed equity financing round, which closed in March, that brings its total to just under half a billion dollars. That could make it one of the most well-funded startups. Period.

Roscheisen says the funding comes from power company AES, the Carlyle Group, French utility EDF and Energy Capital Partners, which made investments through Riverstone Holdings, and EDF Renewables; the funding occurred at the same time as AES and Riverstone formed AES Solar, and the funding was part of the business case for forming the joint venture, Roscheisen explains. A smaller part of the round came from Lone Pine Capital, the Skoll Foundation, Pierre Omidyar’s fund, GLG Partners, Beck Energy, and Grazia Equity.

Roscheisen says the funding will go toward ramping up production of the 430 MW San Jose plant and the 620 MW Berlin factory. Nanosolar has been producing its thin-film solar product for utilities since December. But given we’ve seen a few U.S. utilities sign solar power contracts that included thin film solar — PG&E with OptiSolar and Southern California Edison with First Solar — we asked Roscheisen if Nanosolar has been bidding on solar power projects in the United States. Rocheisen tells us that yes, Nanosolar is involved in U.S. utility solar bids through the AES partnership.