A Solar Hybrid: Crystalline Silicon and Thin Film in One Cell  

Earth2Tech has a post on hybrid solar cells using both thin film and regular silicon PV technology - A Solar Hybrid: Crystalline Silicon and Thin Film in One Cell.

Who says a solar company has to choose between conventional silicon and thin-film solar cells? RoseStreet Labs Energy, a Phoenix-based private company, is combining the two in a double-layered cell that it claims can achieve “practical efficiencies” – meaning efficiencies of cells actually available on the market, not just in the lab – of 25 to 30 percent. On Monday, the company announced the world’s first (or as RoseStreet put it, the “first known”) nitride/silicon tandem solar cell, which it plans to produce in the fourth quarter of next year.

The potential efficiency might not sound breathtaking considering that the National Renewable Energy Laboratory and the Defense Advanced Research Projects Agency both announced last year that they had produced cells that achieved more than 40 percent efficiency in the lab. But lab efficiencies and production efficiencies are not the same thing, and the highest efficiencies for mass-produced solar cells hover around 22 percent. SunPower Corp., which introduced 22-percent efficiency monocrystalline cells in 2007, last year announced it had produced a prototype with 23.4 percent efficiency, which it expects to launch commercially next year.

RoseStreet thinks its new hybrid cell – which “marries low-cost nitride thin film with the massive infrastructure of silicon solar cells,” as CEO Bob Forcier said in the press release – could be cheaper than crystalline silicon cells. The nitride film, the same material used in solid-state lighting and blue lasers, enables the cells to make use of more of the light spectrum, Forcier told us.