It's been an interesting few weeks in the CIGS photovoltaic panel world.

Solyndra went bankrupt; Intel is transforming MiaSolé, Ascent found an Asian white knight -- and now, so has HelioVolt. Today we learned that HelioVolt is receiving $50 million from SK Innovation, South Korea's biggest refiner and a company that accounts for 10 percent of South Korea's gross domestic output. This news leaked out in Bloomberg News -- we'll get you an update later today. SK has an existing battery business.  

SK Innovation's stake was not revealed.

In April, we learned that HelioVolt had put itself up for sale. This is being framed as an investment from SK, not an acquisition.

Once again, an oil giant, as in the Total/SunPower arrangement, has made its move into solar.

According to Scott Sandell, a general partner with VC firm and HelioVolt investor New Enterprise Associates, in an earlier interview with Reuters, the Austin, Texas-based company's investors decided a few months ago that "we really needed to find a partner that could bring a lot more capital to bear."

HelioVolt was founded in 2001, received its initial VC funding in 2005, and aims to fabricate CIGS solar panels using a process the firm calls "reactive transfer."

Ten years since their founding and about $150 million in venture funding later, HelioVolt has shipped no commercial product of consequence.

The firm does boast a monolithically integrated module structure (as opposed to a selected cell architecture like Nanosolar), as well as some encouraging NREL efficiency test data.

HelioVolt has been backed by Masdar Clean Tech Fund, Morgan Stanley, New Enterprise Associates, Paladin Capital Partners Fund, Solucar Energia, Sunton United Energy, Texas Emerging Technology Fund, and Yellowstone Capital.

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An incomplete list of thin film solar firms, VC-funded and otherwise:

CIGS: AQT, Global Solar, Heliovolt, ISET, MiaSolé, Nanosolar, NuvoSun, SoloPower, Odersun, Solyndra, Sulfurcell, Stion, Telio, Solar Frontier, Wuerth Solar

CdTe: Abound Solar, Primestar, Solexant, Bloo Solar, Willard and Kelsey, Xunlight26

a-Si: Sharp Solar

Others: Alta Devices,  Precursor Energetics (which is developing a high-efficiency ink for CIGS films)