Pickens writes "Two photovoltaic solar power plants will be built in San Luis Obispo County in California, covering 12.5 square miles, that together will generate about 800 megawatts of power, the latest indication that solar energy is starting to achieve significant scale. 'If you're going to make a difference, you've got to do it big,' said Randy Goldstein, the chief executive of OptiSolar. OptiSolar will employ enough of its amorphous silicon thin-film solar panels at its Topaz Solar Farm project to generate 550 MW. Meanwhile, SunPower will install mechanical tracking for its more expensive 250 MW-worth of crystalline silicon photovoltaics at High Plains Ranch II in a bid to boost their efficiency by 30 percent from following the sun across the sky. 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 to be competitive with other renewable energy sources, including wind turbines and solar thermal plants. 'These landmark agreements signal the arrival of utility-scale PV solar power that may be cost-competitive with solar thermal and wind energy,' said Jack Keenan, chief operating officer and senior vice president for PG&E." Reader thefickler notes some related news that researchers have developed a method of collecting infrared rays at night to supplement day-time solar power.