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State Grid Operators Prepared to Manage Power Flows During Solar Eclipse

No negative impacts for SCE customers are expected from the Aug. 21 celestial event.

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The Southland will experience a partial solar eclipse on Aug. 21 that will affect Southern California Edison’s service territory, obscuring 58 to 76 percent of the sun’s light for about three hours in the morning (9 a.m.-noon).

That may sound like it will substantially darken the sky, but the effect will be more like a cloudy or overcast day and should not impact the daily activities of Southland residents.

But for the California Independent System Operator staff responsible for balancing the flow of power on the state’s electrical grid, planning for the event began months ago.

Grid operators, including those at SCE, are prepared to manage the effects of the eclipse on the state’s solar power production. About 10 percent of the power SCE provides to customers comes from solar and the utility has more than 230,000 customers with solar panels on their homes or business.

solar eclipse
SCE electrical grid operators are prepared to manage the effects of the eclipse on the utility’s system. 

“One of the advantages of being a national leader in the amount of solar energy connected to the grid is that our operators are experienced with dealing with fluctuations in solar power production due to weather conditions, such as stormy or cloudy weather,” said Paul Grigaux, SCE vice president of Transmission Substations and Operations. “SCE expects no operational issues with our system due to the eclipse, and we have accounted for the anticipated reductions in solar production in our forecasts and planning for the day.”

California has long been a leader in solar production and the system operator expects the reduction in the sun’s light to reduce the output of commercial solar power plants in the state and create a roughly 6,000-megawatt shortfall relative to a normal day — an amount that could power a large city.

To compensate, the independent system operator and utilities will balance the state’s energy needs by adding power generated by hydroelectric and natural gas plants and customers should not notice any effect during the eclipse. SCE operators will complement the effort within its system in Southern California.'

solar eclipse
This graphic shows how the placement of the moon causes a solar eclipse.

Balancing the system can be approached both by adding power and reducing electricity demand, and conservation always benefits the system and customers. The state grid operator has not asked customers to conserve in anticipation of the eclipse, but to be prepared for circumstances that may require a Flex Alert. Flex Alerts ask customers to voluntarily conserve energy to help ease pressure on the system.

“We expect that the eclipse will have a minimal impact on the SCE transmission and distribution systems and that the CAISO will have adequate resources available, so this is an event we can both manage,” said Grigaux. “Most importantly, customers should not notice any difference in their service. Providing safe, clean, reliable energy is what we strive for every day in managing the grid.”  


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