FOLSOM, Calif. – When the moon partially obscured the sun here on Monday, dozens of engineers watched from a large, gray control room outside Sacramento.
Electric grid operators at the California Independent System Operator (CAISO), which delivers 80 percent of the electricity in a state that has more solar energy capacity than every other state in the country combined, watched intently as solar generation began collapsing here at 9 a.m. Pacific Standard Time as the shadow of the moon swept from west to east across the United States.
Above them hung a wall of screens charting the 26,000 miles of high-voltage transmission lines winding through California. One screen showed the state losing half of its solar ability during the morning of the eclipse before spiking back up to normal. Grid operators didn’t don eclipse glasses but instead focused on the task at hand – working in a windowless room to keep the lights on elsewhere in California, without even seeing the event firsthand.
The scene offered a rare window into what might happen as the Golden State’s electric grid – and indeed the nation’s – becomes increasingly reliant on renewable sources like solar and wind to meet Americans’ energy needs while curbing the amount of greenhouse gases those needs generate.
Right now, solar energy provides only a small slice – slightly less than 1 percent in 2016 – of the electricity generated by utilities in the United States and nearly 10 percent in California alone. But that sliver, much as the crescent of the sun swells after a total eclipse, is only expected to grow as the price of solar panels continues plummeting.
Other states like North Carolina, which also sports many solar panels, had to adjust as Monday’s squeezed their energy supply for several hours.
For most of them, the eclipse went off without a hitch.
“Things went really, really well,” said Eric Schmitt, vice president of operations at the CAISO.
In California, hydroelectric and natural gas-fired power plants, along with power drawn from seven surrounding Western states as part of preexisting agreements, stepped in to make up for the loss of between 3,000 to 3,500 megawatts in solar power, according to initial estimates from the CAISO. FFor a cloudless August day, the grid operator estimated a loss of about 6,000 megawatts from both solar panels owned by homeowners and utility-scale solar facilities.
Nature helped, even if it blotted out the sun in the first place. The weather was generally mild statewide, meaning fewer Californians likely turned on their air conditioners. And elevated reservoirs at the Helms Pumped Storage Plant in the Sierra Nevada, for example, were flush with water from the rainy season that was used to power hydroelectric pumps.
California Survives the Eclipse without Losing Any Energy, by Dino Grandoni, The Washington Post, August 21, 2017.