Sunny California will see its skies darken for about three hours in mid-October by a rare annular eclipse, and officials now are working overtime with regional authorities, as well as natural gas interstate and intrastate suppliers, to ensure there are adequate resources available to make up for the expected solar shortfall.

An all-hands effort is underway, led by the California Independent System Operator (CAISO), for the partial eclipse, which is set to darken large swaths of the state beginning at 8 a.m. PT on Oct. 14. As the eclipse moves east, maximum obscuration in California is estimated to arrive at 9:30 a.m. 

“On the eclipse day, partial obscuration of the sun will reduce output of rooftop solar and increase load by 4,843 MW or 29.6% at 9:15 a.m. relative to normal...