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The solar eclipse could block 9,000 megawatts of solar power

That’s enough electricity to power 7 million homes

The solar eclipse on August 21 will offer a unique challenge to the country’s growing solar industry.

The approaching August 21 solar eclipse, which will traverse the continental United States, is expected to cause numerous disruptions, as curious Americans take time off or even travel to witness the celestial anomaly. Businesses across the country are gearing up, but few are taking it as seriously as solar power operators.

According to a release from Climate Nexus, the brief period of darkness will have a sizable impact on the nation’s growing number of solar installations. Expected to stretch across 14 states, the eclipse will obstruct as much as 9,000 megawatts of solar power, or the equivalent of nine nuclear reactors. That would be enough power to supply 7 million homes.

The impact will be most clearly felt in California, which can rely on solar for up to 40 percent of its power on certain days. Experts estimate that state alone will lose roughly 4,194 megawatts of generating capacity. Other solar-heavy states expected to see an impact include North Carolina and New Jersey (despite being outside of the direct 70-mile wide path of the eclipse).

This energy challenge results from solar’s growing popularity over the last decade. At of the end of 2016, the U.S had 1.4 million solar installations. According to Bloomberg, rooftop panels will account for 80 percent of outages.

U.S. Quarterly PV Installations, Q1 2012 - Q1 2017
GTM Research

The temporary loss of power, however, has already been anticipated by utilities that rely on solar. According to the release, grid operators don’t anticipate any power outages or price impacts due to the eclipse.

“The eclipse presents some grid management challenges for California and the West,” Nancy Traweek, the executive director of systems operations for the California ISO (CAISO), the state’s power grid, said in a statement. “However, with detailed planning and engagement among all parties we are expecting no shortage of electricity or reliability incidents related to the eclipse.”

During the eclipse, CAISO says it will fill any power gaps with natural gas and hydropower, and has already begun reaching out to customers to request they lighten their energy load during the big event. CAISO also reached out to German grid operators to learn any lessons they may have picked up from their experience with a 2015 European eclipse. Dealing with this event will present important lesson for U.S utilities to learn; during the next anticipated U.S. eclipse in 2024, solar power will likely be an even bigger part of the nation’s power system.

PJM Interconnection, which serves 65 million customers across 13 eastern states, operates the largest grid in the country. In a press release, the utility says that when the moon blocks the sun on the afternoon of Aug. 21, it expects a temporary reduction in solar power of up to 2,500 megawatts, depending on how sunny or cloudy it is that afternoon. PJM also says that it has ample options at hand to cover the disruption in solar generation.