August solar eclipse could strain California’s electricity supply

The near-total solar eclipse arriving Aug. 21 could strain California’s electricity supply.

An alert issued Thursday by the Public Utilities Commission is testament to how much Californians depend on solar energy. The PUC didn’t warn of blackouts, but is calling on utility customers to turn off or unplug appliances, postpone using washing machines and taking other steps to conserve electricity during the eclipse.

“When the sun goes away, so does the energy that powers our renewable solar panels,” said PUC President Michael Picker in a prepared statement.

The eclipse is expected to last from about 9 a.m. to noon. The sun will be 76 percent obscured in Northern California and 62 percent in Southern California, according to the PUC.

At the peak of the eclipse, the PUC said state’s major investor-owned utilities will lose about 5,600 megawatts of solar-electricity capacity. That won’t plunge homes and businesses into darkness, but it could put a strain on supplies. The PUC is asking for conservation measures as an alternative to ramping up production from the state’s portfolio of natural gas-fired plants.

The Independent System Operator, which runs the transmission grid serving about 70 percent of California, said solar accounted for 9 percent of California’s electricity needs last year. That was a one-third increase from the year before.

The ISO said it doesn’t expect serious problems Aug. 21 but acknowledges it doesn’t know what the energy picture will look like when the sky starts going dark.

“We could be in the middle of a big heat wave,” said ISO spokesman Steven Greenlee. “There could be wildfires playing havoc with transmission wires.”

The eclipse will be a big one. The sun will be totally eclipsed to those viewing in a swath about 70 miles wide, running from Oregon to Charleston, S.C., according to NASA.

This will mark the first total solar eclipse in the continental United States since 1979, although that one was only visible in five states and was hampered by lousy weather, according to Astronomy.com.

Since then, California has embraced solar energy. Commercial solar farms are popping up throughout rural California. More than 450,000 customers of the major utilities, Pacific Gas and Electric Co., Southern California Edison and San Diego Gas & Electric, have solar panels, according to the PUC.

About 3 to 4 percent of SMUD’s power is generated by solar, said Sacramento Municipal Utility District spokesman Chris Capra.

The eclipse comes as California pushes to increase its reliance on solar and other renewable energy sources. By law, utilities must generate half of their electricity from renewables by 2030, and Democratic lawmakers have introduced a bill that would require California to go all-renewable by 2045.