Silicon solar cell startup Suniva is on its way to triple its manufacturing capacity, which would enable it to better compete with competitors with much larger factories.
The Norcross, Ga., company has begun manufacturing at its new 64-megawatt line, and expects to reach full production run by the end of this quarter, said Brian Ashley, vice president of manufacturing and sales. The company began commercial production on a 32-megawatt line last October.
Suniva's technology grew out of research by Ajeet Rohatgi at the Georgia Institute of Technology. Rohatgi founded the company and set out to commercialize a process to make cheaper monocrystalline silicon cells. The company makes cells and sells them to companies that assemble the cells into panels.
Crossing the 100-megawatt capacity would be crucial for any startup company wishing to compete with large competitors in the United States, Europe and Asia -- and they are many. The larger you are, the more easily you are able to shave manufacturing costs.
Besides announcing a manufacturing expansion, Suniva also said Wednesday that solar cells coming off its production line, branded ARTisun, could convert "more than 18 percent" of the sunlight that strikes them into electricity. The figure isn't verified by an independent lab, however.
Back in September, the company said its cells made with the ARTisun technology in its lab could achieve 18.5 percent efficiency. Suniva's researchers also were able to fabricate other cells that could achieve roughly 20 percent efficiency, a claim the company said was verified by the National Renewable Energy Laboratory.
Lab-made cells tend to have higher efficiencies than what can be achieved in a factory, where the process of producing cells in high volumes could cause snafus that affect the quality of the products.
Improving the efficiency of its commercial cells is important for Suniva deliver on its claim that it could make highly efficient cells at low production costs, which would lead to cheaper electricity. The company hasn't disclosed its manufacturing costs.
The new efficiency number for its commercial cells also puts Suniva in a club of companies that are producing more efficient silicon cells than most.
Suntech Power in China, for example, is using a new process it calls Pluto that has produced commercial cells with 18.8 percent efficiency. The Fraunhofer Institute for Solar Energy Systems in Germany verified the efficiency claim.
SunPower in San Jose, Calif., meanwhile, has been producing monocrystalline silicon cells with a little over 22 percent efficiency for about two years now. The company's panel holds a world record (20.3 percent),
Suniva is using a conventional screen printing method for making the metal contact lines on the front of the cells, unlike SunPower and Suntech, said Suniva's spokesman David Briggs. Contact lines are metal, typically silver, that transport electricity generated from each cell.
The conventional method is cheaper than fancier processes and has been around for decades. But it poses limitations that make it more difficult to improve efficiencies, which hover in the mid-teens. Figuring out a way to gain efficiencies while using screen printing enables Suniva to make higher performing cells with a low-cost method.
Suniva is able to print thinner metal lines so that more of the cells' surface is exposed to sunlight. The company also has figured out a way to manipulate the texture of the cells to allow them to trap more light. Other startups, such as 1366 Technologies in Lexington, Mass., also are working on similar improvements.
SunPower also uses screen printing, said spokeswoman Helen Kendrick. But the company has an unusual approach of creating the contact lines on the back of the cells, and that frees up space on the front of the cells to trap more light.
Suntech's Pluto technology does make use of screen printing, but not the conventional kind, said Martin Green, a professor at the University of New South Wales whose research led to the Pluto technology. Green led the team that created the world's most efficient silicon cell (25 percent), according to Progress in Photovoltaics, a scientific journal that keeps track of efficiencies achieved by companies and research institutions.