The push to design green has turned the photovoltaic market into a $4 billion global industry that grows an average of 20% to 25% a year. Richard King, team leader for photovoltaics research and development for the U.S. Department of Energy (DOE), says the U.S. photovoltaic industry currently generates about 120MW a year, but by 2020, the nation could produce a few gigawatts. By bringing down the cost of the technology, the photovoltaic market could follow its current growth pattern and double every two to three years. To fuel growth in the industry, the DOE launched its Million Solar Roofs Initiative to install solar energy systems on 1 million U.S. buildings by 2010.

“Photovoltaics could eventually become 10% of the new electricity generation going up in the country,” King says. “Since 1980 we've created an industry, and now it's up and running. The more electricity we can get from clean technologies, the better off we are.”

The photovoltaic market has also experienced a fundamental shift from a “mom-and-pop” business to a multi-billion dollar global industry. Large corporations are now trying to become more competitive by establishing “green teams” to look for ways to eliminate waste, conserve energy, and build energy-efficient buildings.

Several factors are driving the commercialization of photovoltaics — state rebates and incentives, the current cost of conventional electricity in large cities like New York City and Los Angeles, environmental building guidelines, concern over climate change, and net metering. About 36 states currently have net metering laws, which allow a consumer to run the electrical meter backward if the energy production exceeds the energy consumption.