Another Solar Record Set, Renewables Power Nearly Quarter of California

Yet another milestone in California's quest to go solar: the state's industrial-sized solar power producers pumped more than 4,500 megawatts into the grid around noon on Monday.

According to the California Independent System Operator (CaISO), the agency that runs the grid serving most of California, utility-scale solar power plants set a new record of 4,566 megawatts of output at 12:03 p.m. on May 19.

Around 575 megawatts of that noontime peak came from solar thermal plants, which use the sun's energy to generate steam which in turn turns turbines. The remainder came from photovoltaic panels, which convert sunlight directly into electricity.

As always when we report on utility-scale solar peaks reported by CaISO, there are a few things to keep in mind. First, the actual amount of solar power generated in the state and fed into the grid was significantly larger Monday. CaISO measures only those large energy generators that are hooked up to the grid without a consumer's electric meter in between them. That means that none of the residential or commercial rooftop solar in the state counts toward that 4,566-megawatt total.

According to the California Solar Statistics website, there were at least 2,050 megawatts of rooftop solar capacity installed in California as of May 14, and that figure omits a significant amount of California solar. There are at least 216 megawatts of solar in Los Angeles, San Diego, and San Jose alone not reflected in the California Solar Statistics' site's totals.

Secondly, even with the growing output of California solar, the state still lags well behind more forward-looking places like Germany, which by July 2012 had 29,700 megawatts of solar panels installed.

Caveats aside, Monday was a banner day for California renewables in more ways than just setting a heavily qualified solar output record: Renewables met almost a quarter of the state's power demand for the day. Monday's total power output from solar, wind, geothermal, biomass, and small hydro amounted to 149,895 megawatt-hours, which was around 24 percent of the state's total 24-hour demand of 627,144 megawatt-hours.

149,895 megawatt-hours worth of renewable energy is 149,895 megawatt-hours of power we didn't need to generate by burning natural gas, the conventional fuel of choice in California. Generating that much power in a natural gas fired plant would have released about 83,000 metric tons of CO₂ into the already over-CO₂ed atmosphere.

So there's that.