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Why the solar eclipse could strain California’s electricity supply

Watch the total solar eclipse in Indonesia in 35 seconds

Members of Slooh watched and captured the total solar eclipse from Indonesia on March 8, 2016. Slooh is a community observatory dedicated to bringing astronomy from the stars to screens, according to representatives. It regularly live broadcasts m
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Members of Slooh watched and captured the total solar eclipse from Indonesia on March 8, 2016. Slooh is a community observatory dedicated to bringing astronomy from the stars to screens, according to representatives. It regularly live broadcasts m

Solar panels have become a prominent feature of California’s landscape, sprouting from rooftops, parking lots and farm fields as badges of the state’s commitment to renewable energy.

But what happens when the sun goes dark on a hot summer day? Californians could find out in August.

The Public Utilities Commission warned this week that the state’s electricity supply could be strained by the near-total eclipse Aug. 21.

The PUC didn’t warn of blackouts but called on utility customers to turn off or unplug appliances, postpone using their washing machines and take other steps to conserve electricity during the eclipse.

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 squeeze on supplies. The PUC is asking for conservation as an alternative to ramping up production from the state’s portfolio of natural gas-fired plants.

The Independent System Operator, a quasi-state entity that runs the transmission grid serving about 80 percent of California, doesn’t expect serious problems, either. But the ISO acknowledged it doesn’t know exactly what the energy picture will look like when the sun starts disappearing that morning.

“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.”

Either way, the PUC’s alert is a testament to California’s growing dependence on solar energy. Solar accounted for about 9 percent of California’s electricity needs last year, Greenlee said. That was a one-third increase from the year before.

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.

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

Others outside of California will see a total eclipse. The sun will be completely obscured in a swath about 70 miles wide, running from northern 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 to a degree rarely found in other states. 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 percent 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. Solar makes up about half of California’s renewable energy supply.

Talk about interesting timing: Aug. 12, 2045, is the scheduled date of the next major solar eclipse in the United States, according to GreatAmericanEclipse.com.

NASA's Solar Dynamics Observatory captured video of a double solar eclipse from space. SDO caught both Earth and the moon passing in front of the sun on the morning of September 1.

Dale Kasler: 916-321-1066, @dakasler

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