California utilities work to restore power after Tropical Storm Hilary

California utilities are working to restore power after Tropical Storm Hilary blew through Southern California, causing solar generation to plummet as storm clouds covered much of the state.

Hilary weakened from a hurricane to a tropical storm before it made landfall Aug. 20 on the northern Baja California Peninsula and later moved into Southern California.

"After moving inland across Southern California late Sunday, moisture associated with Hilary is forecast to continue streaming northward through the Intermountain West [Aug. 21]," the US National Weather Service said in its Aug. 21 daily discussion.

Several areas in Southern California reached new low temperature records Aug. 20 and set daily precipitation records. Lake Cuyamaca received 4.11 inches of rain, breaking a 1984 record, while San Diego received 1.82 inches of rain, breaking a record from 1906, according to the weather service. In Palm Springs, 3.18 inches of rain fell Aug. 20, bringing the monthly total to 3.1 inches above normal, according to the weather service.

"We're already back to normal weather, which will allow crews to access where the outages are," Southern California Edison spokesperson Jeff Monford said.

Power outages

At the peak outages, there were roughly 500,000 customers without power, according to utilities. There were more than 51,000 outages across California as of 1pm CT Aug. 21.

SCE had 10,643 customers without power as of 9:30am PT Aug. 21, down from 380,154 Aug. 18, Monford said.

The storm caused a considerable amount of wind damage across Pacific Gas and Electric service territory that caused a total of 68,100 customers to lose power, spokesperson Denny Boyles said. The majority of the remaining roughly 12,000 outages were expected to be restored Aug. 21.

"Most of the severe impacts from the Tropical Storm happened south and east of our territory," Boyles said.

San Diego Gas & Electric has about 15,000 customers without power at the peak of outages and most were restored without a few hours, spokesperson Candace Hadley said. By 10:30am PT Aug. 21, there were about 100 storm-related outages remaining.

"We do not anticipate any further storm related outages at this time; however, situational changes and unplanned outages are always possible," Hadley said.

The California Independent System Operator grid is stable with sufficient supplies forecast, spokesperson Anne Gonzales said.

Solar generation impacts

The cloud cover from the storm significantly decreased solar-powered generation for the CAISO footprint as most solar facilities are located in Southern California.

Solar market share plummeted to 4.4% of the total fuel mix Aug. 20, a seven-month low, according to CAISO. Thermal, wind and imports each increased about 2 percentage points day on day to fill in the gap.

Solar generation output dropped to 3.715 Aug. 20 but is forecast to jump 173% day on day to a high of 10.131 GW Aug. 21, according to CAISO data. In comparison, solar generation has averaged 12 GW so far this month.

Last month, solar generation set a peak record of 15.96 GW July 6, according to CAISO's Key Statistics report for July.

Peakload dropped to 30.577 GW Aug. 20, a 42-day low and the lowest daily August load in two years, according to CAISO data.

California Governor Gavin Newsom proclaimed a state of emergency Aug. 19 for much of California ahead of the storm's impact. He expanded on Aug. 20 the number of counties under the state of emergency proclamation.