Are you ready to bring more awareness to your brand? Consider becoming a sponsor for The AI Impact Tour. Learn more about the opportunities here.

Thin-film solar company Nanosolar has been sitting on a big secret for much of this year, it turns out: The company took a $300 million financing this March, and has remained mum ever since, only detailing it on the company’s blog this morning after VentureWire reported the funding.

While Nanosolar hasn’t been entirely secretive about its technology, with chief executive Martin Rosencheisen showing off a rapid manufacturing technique early in summer, but apparently it didn’t want details leaking on this giant-sized investment until necessary. Word slipped out in April about $50 million of the total, but at the time, Nanosolar didn’t want to talk — and it’s now clear why.

The race for funds, and ever-larger production targets, is definitely on for thin film. Secretive thin-film silicon company Optisolar has raised over $200 million this year, and Nanosolar’s thin-film CIGS competitor Miasole is trying to close on a similar amount. And while dozens of other startups are also on the hunt, large companies like Oerlikon Solar and Applied Materials are pouring money into ventures of their own.

In many ways, it looks like an overheated sector. But on the other hand, Optisolar’s recent deal with PG&E to provide 550 megawatts of electricity suggests that the potential for thin film panels is larger than previously expected, even when considering one analyst firm’s prediction earlier this year that the sector will grow at 45 percent annually.

That figure could now be much higher, especially for a few big winners — of which Nanosolar will likely be one. The company will be doing some utility-scale projects of its own, Rosencheisen tells us, with experienced partners. It also has a panel built specifically for use by utilities. And one of the backers of this funding, AES Corp., is also one of the world’s biggest power companies.

At the moment, Nanosolar is still working toward a gigawatt of annual manufacturing capacity, but it will grow beyond that after completing its plants in Palo Alto, Calif. and Germany.

The backers in the funding were mainly private equity firms and large companies: EDF Energies Nouvelles, AES Solar, Riverstone Holdings, Energy Capital Partners, the Carlyle Group, Lone Pine Capital, and the Skoll Foundation. Previous backers GLG Partners and Beck Energy also joined in. The company has taken almost half a billion dollars to date, including grants.

VentureBeat's mission is to be a digital town square for technical decision-makers to gain knowledge about transformative enterprise technology and transact. Discover our Briefings.