Cheap and dirty solar

A research team led by engineers at the University of California, Berkeley, has developed a new technique to handle metal defects in low-grade silicon, an advance that could dramatically reduce the cost of solar cells.

Nearly 90% of solar, or photovoltaic, cells in the world are made from a refined, highly purified form of silicon, the same material used to make integrated circuits. But the growth of the semiconductor and solar cell industries has put increasing pressure on relatively limited supplies of this high-quality silicon, consequently driving up the price of the material.

Attempts to use the far more abundant and cheaper form of silicon - one that is laden with metal impurities and defects - have failed because solar cells made from this material do not perform as well. In addition, manufacturing techniques used to remove impurities are expensive, negating the cost benefits of using the cheaper material.