According to the U.S. Energy Information Administration, the solar eclipse forecast for August 21 will impact energy production at approximately 1,900 utility-scale solar photovoltaic (PV) power plants in the United States. The good news is that only 17 of these plants lie in the path of totality—where the sun will be completely obscured by the moon for about 90 minutes. However, these locations will need to make adjustments to protect against service disruptions.
These solar-powered generators will only be without sunlight for about three minutes, but will have to operate without the same amount of sunlight for the entire duration of the eclipse, which will last about three hours. Plants that generate a total of about four gigawatts (GW) of capacity—mostly in North Carolina and Georgia—will be at least 90 percent obscured during totality.
Another 2.2 GW and 3.9 GW of capacity are in areas that will be at least 80 percent and at least 70 percent obscured, respectively. One gigawatt is enough to power about 700,000 homes. During the eclipse, electric generators will be asked to pick up the slack and increase their output.
This includes plants in California that generate 8.8 GW of utility-scale solar, which represents 40 percent of the U.S.’s total solar output. The eclipse will cut this total in half. To compensate, the state plans to replace solar generation with electricity from natural gas and hydropower plants.
North Carolina has the greatest number of PV installations that will be at least 90 percent obscured. Duke Energy, one of the largest utilities in North Carolina, estimates that solar energy output across their system will drop from about 2.5 GW to 0.2 GW at the height of the eclipse. The state will also use electrical generators to compensate for the power loss.