5MW supply deal for cell maker Solar Junction

25 May 2012

Venture-backed developer of high-efficiency, multi-junction cells signs agreement with concentrated PV specialist SolFocus.

SolFocus, the US-based company at the forefront of concentrated photovoltaics (CPV) systems that generate utility-scale electricity by focusing sunlight onto very high-efficiency solar cells, has agreed a 5 MW supply deal with cell developer Solar Junction.

The agreement follows the latest round of financing closed by SolFocus, with the company raising a further $10.75 million in equity investment earlier this month. One of the SolFocus investment partners named on the company’s filing, New Enterprise Associates, is also an investor in Solar Junction.

Last year, San Jose-based Solar Junction developed a solar cell with a world-record efficiency of 43.5%. Unlike the silicon or CdTe PV modules that are now seen commonly, these high-efficiency devices are manufactured from III-V semiconductors – meaning that they are much more complex and expensive to produce.

However, when sunlight is highly concentrated using either reflective or refractive optics onto one of the tiny cells, it generates far more power per unit area than a conventional solar cell – meaning that in sunny climates the approach has the potential to be highly cost-effective.

Jim Weldon, Solar Junction’s CEO, said of the SolFocus agreement: “It is great to see growth in the sales and manufacturing sides at Solar Junction. It’s an indication that ‘technical’ innovation in solar will win the day.”

The backing for CPV technology comes at a time when the mainstream PV industry is in a state of turmoil caused by sudden changes to subsidization policies in key markets, and plummeting prices of crystalline silicon cells and panels partly caused by the low technical barrier to entry in producing those cells in volume.

SUNPATH award
Last year, Solar Junction had been hoping to receive a Department of Energy (DOE) loan guarantee to help finance a scale-up of its manufacturing facilities in California. However that deal did not come to pass, and earlier this year the company instead signed an equity and manufacturing agreement with IQE, the UK-headquartered company that specializes in III-V semiconductor wafer production.

Since then, Solar Junction has also won a “SUNPATH” (Scaling Up Nascent PV at Home) award from the DOE, as part of the wider “SunShot Program” that is seeking to make PV technology price-competitive with conventional energy sources by the end of the decade.

Announced last August, the SUNPATH program was set up to allocate a total $50 million towards projects that promise to help the US “reclaim its competitive edge in solar manufacturing”. The program is intended to help companies with pilot-scale facilities scale up to full production.

Through its SUNPATH funding and the IQE manufacturing agreement, Solar Junction is aiming to produce CPV cells with a median efficiency of 42% on 6-inch semiconductor wafers. The company’s proprietary approach uses so-called “dilute nitride” semiconductor layers (layers of GaInNAs material in the semiconductor stack to produce a 1 eV absorber, meaning that more of the solar spectrum can be absorbed by the cell).

Solar Junction also uses gallium arsenide wafers instead of the more typical germanium substrates on which to produce the cells, something that ought to help decrease the cost of the cells thanks to wider availability.

Last year, the company told optics.org that it could see a pathway to producing cells with an efficiency of 50%, by adding further junctions to the semiconductor stack – although this would inevitably come at a higher cost.

SolFocus, which unlike most CPV developers is using reflective mirror optics in its modules, recently agreed a major deal to supply thousands of systems for the first part of a huge 450 MW solar farm being built in the northern Mexico region of Baja California.