According to The Earth Policy Institute production of photovoltaics (PV) jumped to 3,800 megawatts worldwide in 2007, up an estimated 50 percent over 2006. At the end of the year, according to preliminary data, cumulative global production stood at 12,400 megawatts, enough to power 2.4 million U.S. homes. Growing by an impressive average of 48 percent each year since 2002, PV production has been doubling every two years, making it the world’s fastest-growing energy source.

A key force driving the advancement of thin-film technologies is a polysilicon shortage that began in April 2004. In 2006, for the first time, more than half of polysilicon production went into PVs instead of computer chips. While thin films are not as efficient at converting sunlight to electricity, they currently cost less and their physical flexibility makes them more versatile than traditional solar cells. Led by the United States, thin film grew from 4 percent of the market in 2003 to 7 percent in 2006. Polysilicon supply is expected to match demand by 2010, but not before thin film grabs 20 percent of the market.