Semprius to Produce Dot-Sized, Low Cost-High Efficiency Solar CPV Cells, Modules at NC Plant

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Tiny solar cells developed by Durham, NC-based Semprius were validated by the US Dept. of Energy’s (DOE) National Renewable Energy Lab (NREL) as achieving an energy conversion efficiency of greater than 41% at a concentration of 1,000 suns. That’s one of the highest efficiencies ever recorded at this level of concentrated sunlight, NREL announced Dec. 14.

With seed funding from the DOE and the help of experts at the NREL-based SunShot Incubator Program, Semprius now aims to manufacture and commercialize its technology utilizing its patented micro-transfer printing process, a low cost, massive parallel process that simultaneously transfers thousands of the preformed circuit elements from a source semiconductor to almost any other substrate.

Construction of Semprius’s manufacturing plant in Henderson, NC began earlier this year. North Carolina and local agencies contributed $7.9 million for the 50,000-square foot plant, which is expected to employ 256 people at full build-out. The plant’s due to be commissioned in 2012 with an initial capacity of 5 megawatts (MW), expanding to 35 MW over time.

Tiny CPV Cells Competitive with Fossil Fuels

The market for highly-concentrated solar photovoltaics (CPV) is expected to at least double every year over the next nine years, reaching greater than 10 gigawatts (GWs) of power by 2020, according to Semprius CEO Joe Carr. The modules produced at the Henderson plant will be 24 inches by 18 inches, and about 2-1/2 inches deep, have a concentration of more than 1,100 suns and an efficiency of more than 31%. It’s believed that Semprius’s CPV modules would be cost competitive with fossil fuel technology at high volume.

About the diameter of a dot made by a ballpoint pen, Semprius’s solar photovoltaic (PV) cells are triple junction cells made of gallium arsenide. Low cost lenses concentrate sunlight 1,100-times onto the cells. Their tiny size reduces module cost as they take up only 1/1000th of the entire solar module area. It also enables a high density of cells per module, which better distributes unwanted heat across the entire solar module solar area. That eliminates the need for heat dissipation hardware, such as heat fins, further reducing production costs.

Semprius’s patented micro-transfer printing process allows thousands of its concentrated solar PV cells (CPV) to be transferred from a growth substrate to a semiconductor wafer or other form factor. It’s a continuous, massive parallel process that runs continuously and allows the growth substrate to be used repeatedly, which cuts costs dramatically, according to NREL and Semprius.

The process was originally developed by University of Illinois Professor John Rogers and his R&D team, which they initially envisaged being used to manufacture flexible electronics. Rogers then realized that applying the technology to CPV design could be much more lucrative, NREL recounted.

“We’re using a completely different approach to what has been practiced,” said Kanchan Ghosal, CPV Applications Engineering Manager and the principal investigator for Semprius’ PV Incubator Award. “This approach uses micro-cells and transfer printing to significantly reduce the use of materials in highly concentrated PV modules. And it provides a highly parallel method to manufacture the module, based on established microelectronics processes and equipment.”

Semprius claims its low-cost manufacturing approach by 50%. Progress to data has been enough to grab the attention of multinational power industry giant Siemens, which took a 16% equity stake in the company as part of a $20 million investment from venture capitalists.

The venture capital investment further illustrates how federal government investment, scientific and technological research, development and support is being leverage by private sector companies. The DOE has invested $50 million in 35 solar start-ups participating in the SunShot Incubator Program. Private investment in these companies now totals more than $1.3 billion, a 25:1 multiple.