Photo: Joson

It's another brilliant day at the world headquarters of the hottest company on the planet. Some shirtless employees are playing a lunchtime game of volleyball while others stride across campus with laptops tucked under their arms. The place fairly crackles with energy, and in more ways than one.

Up here on a roof at Google's leafy and sprawling Mountain View, Calif., campus, with the shouts of the volleyball game just barely audible, sunlight glints off 9212 polysilicon solar panels stretching out toward the horizon. Amid the irregular jumble of angular roofs, a single south-facing wave stands out, a pitch and roll frozen in place against a backdrop of foothills.

Today, like most days, the panels will generate 9000 kilowatt-hours of electricity before the sun fades into a fat orange ball and disappears into the Pacific. All are connected to Mountain View's section of the electricity grid. The solar modules blanket virtually all the free roof space on the eight buildings at the center of the Googleplex [see "Up on the Roof"]. Even part of the parking lot is covered: two rows of carports, shaped like miniature gas stations, support yet more panels. When the last building is fully connected, by the end of this year, the panels will produce 1.6 megawatts of electricity. It'll be enough to satisfy 30 percent of the buildings' peak demand or power a thousand California homes.

Google's project is the largest corporate installation of solar panels in North America. It has grabbed headlines since Google announced it a year ago. That said, it isn't even in the worldwide top 10 of roof-mounted solar projects. A handful of factories in Germany and Japan take that honor, as well as a couple of roofs in Spain and the Netherlands. At the very least, the search giant's solar play adds one more country to the list of star performers in the world of commoditized sunshine. And it seems clear that Google's array won't be tops in North America for long.

After languishing through much of the 1990s, the market for photovoltaic installations in the United States and several other countries took off about five years ago, and it's now increasing by 40 percent annually in the United States alone [see sidebar, "Photovoltaic Hot Spots"]. Spain's bullish market grew 100 percent in the past year. And percentages never tell the full story, as Noah Kaye, a spokesman for the Solar Energy Industries Association (SEIA), points out. “The German market was relatively flat in the past year, but Germany still installed more [photovoltaics] than the U.S. did,” says Kaye, on behalf of the trade and lobbying group.

California has nonetheless become the second-fastest-growing 
solar market in the world, and that surge, especially in the United States, is being driven mainly by activity on corporate rooftops. Travis Bradford, president of the nonprofit Prometheus Institute for Sustainable Development, in Cambridge, Mass., calls corporate attention to solar power “an exploding interest.” In 2006, the commercial sector accounted for 60 percent of newly installed capacity in the United States, up from 13.5 percent in 2001, according to data from the U.S. Department of Energy.

“We've stopped reporting the biggest systems,” Bradford adds. “A new record is set every few months.”

In March, Applied Materials of Santa Clara, Calif., announced a plan to install 1.9 MW of solar power on the rooftops of its Sunnyvale, Calif., complex. And it's not just high-tech titans retooling their roofs: Tesco, the British-based supermarket chain, says it intends to put up a 2-MW solar installation at an office complex in northern California. Wal-Mart, the world's largest retailer, intends to outshine all these companies with multipart plans to put more than 5.6 MW's worth of solar panels on the roofs of 22 stores in California and Hawaii. Two other discount-retailing giants, Target and Kohl's, have also begun transforming their roofs into tiny, independent utilities.

“It's not an illusion,” says Craig Cornelius, program manager for the Department of Energy's solar division. “Corporate solar is really happening.”