California is showing the awesome potential of scaled-up solar power to provide the United States and the world with clean, renewable electricity. For three hours on March 11 the state got 50 percent of its electricity from solar — 40 percent from large-scale solar power plants and 10 percent from distributed solar installations on homes and businesses. The estimate came from the U.S. Energy Information Administration (EIA), the statistics division of the U.S. Department of Energy. The federal government used data from the California Independent System Operator (CAISO), which manages the electricity grid for 80 percent of California and part of Nevada.
There are enough big solar facilities in California to generate up to 9.8 gigawatts of electricity, nearly matching the output of 10 nuclear reactors. The state is also increasing other renewables such as wind power, biomass, small hydroelectric dams and geothermal power. According to CAISO, on March 23 renewable sources accounted for 56.7 percent of all power on the grid.
What California doesn’t have enough of at this point is large-scale energy storage. On sunny days the state often produces too much solar power that is shunted off the grid, a process known as curtailment. If the state expects to meet its ambitious target of getting half of its electricity from renewable sources by 2030, storage capacity will have to increase.
While Californians continue to pay some of the highest average retail electricity prices in the nation, as more solar is added to the grid there are days when power prices reach zero or even get into negative territory. Zero to negative prices generally occur during late winter and early spring daylight hours. For example, according to EIA, last month during the hours of 8:00 a.m. to 2:00 p.m., system average hourly prices were frequently at or below $0 per megawatt hour.
Images via Brightsource Energy