Lights out: Eclipse to have big impact on California power

SACRAMENTO » When the moon passes in front of the sun during Monday’s eclipse California will lose enough solar energy to power more than 1.5 million homes, a figure that underscores the state’s growing reliance on energy from the sun.

California has rapidly deployed renewable energy and now produces 40 percent of the nation’s solar power. The eclipse presents an unusual challenge for those who manage the state’s power grid because the solar energy will drop off and re-emerge more quickly than during usual conditions involving clouds or nightfall.

For about three hours Monday, there will be diminished solar power available.

Grid managers say they’ve been preparing extensively for more than a year and are confident nobody will lose power. They’ll ramp up other sources of power, mainly hydroelectric and natural gas, as the sky darkens and ramp them back down as the sun re-emerges.

“Our grid operators are going to be functioning very similar to a director of an orchestra, trying to keep everything flowing,” said Lynsey Paulo, a spokeswoman for Pacific Gas & Electric, which serves electric customers in Central and Northern California.

The grid requires power supply and demand to match precisely. Grid managers now have years of experience adjusting power sources when clouds and gusts affect solar and wind energy, which are much less predictable than a solar eclipse.

During the eclipse, however, the sky will darken and lighten two or three times as fast as a usual, according to the California Independent System Operator, which runs the grid for most of California and a small portion of Nevada.

Solar energy now makes up only about 1 percent of the U.S. power supply, but it’s far higher in some areas. On Monday morning solar supplied about 30 percent of the power

for the California ISO, said Deane Lyon, a shift manager. Solar’s precise share fluctuates constantly based on weather and demand.

California ISO projects it will need to replace just over 6,000 megawatts of capacity during the peak of the eclipse, about two-thirds from lost production at commercial solar farms and the rest due to higher demand from people and businesses that would otherwise draw from rooftop solar panels. The Solar Energy Industry Association says California solar panels produce enough energy to power 258 homes on average.

Other areas of the country also will take a hit, albeit a smaller one. PJM Interconnection, the nation’s largest grid operator which manages the power supply in 13 Eastern states and Washington, D.C., anticipates replacing up to 2,500 megawatts of solar capacity.