World's biggest solar plants to be built in California [Again; New Story!]

Two solar power plants to be built in California together will put out more than 12 times as much electricity as the largest such plant today, a fresh indication that solar energy is starting to achieve significant scale.

The plants will cover 12.5 square miles, or 32 square kilometers, of central California with solar panels, and in the middle of a sunny day will generate about 800 megawatts of power, roughly equal to the size of a large coal-burning power plant or a small nuclear plant. A megawatt is enough power to run a large Wal-Mart store.

The power will be sold to Pacific Gas & Electric, which is under a state mandate to get 20 percent of its electricity from renewable sources by 2010. The utility said that it expected the new plants, which will use photovoltaic technology to turn sunlight directly into electricity, to be competitive with other renewable energy sources, including wind turbines and solar thermal plants, which use the sun's heat to boil water.

"These market-leading projects we have in California are something that can be extrapolated around the world," Jennifer Zerwer, a spokeswoman for the utility, said. "It's a milestone."

Though the California installations will produce 800 megawatts at times when the sun is shining brightly, they will operate for fewer hours of the year than a coal or nuclear plant would and so will produce no more than a third as much total electricity.