An upcoming solar eclipse is anticipated to see a significant drop in energy supply to Texas's power grid, as a lack of sunlight will see solar generation suddenly and dramatically decline.
A total solar eclipse—when the sun is completely shrouded by the moon—is set to occur on April 8, passing from northern Mexico across the southwest and into New England. A 100 percent loss of sunlight is due to take place in Texas from around 12:10 p.m. to 3:10 p.m. CT (1:10-4:10 p.m. ET).
According to Hugh Cutcher, a data scientist for solar power forecaster Solcast, most of the continental U.S. will experience a "significant drop" in solar generation, but the Electric Reliability Council of Texas (ERCOT) will be "heavily impacted by the effects of the eclipse."
Solcast projections suggest that, should the skies be clear that day, because the eclipse will occur in the middle of the day, ERCOT's solar production will suddenly drop from nearly 15,000 megawatts to around 1,000 megawatts, before returning to normal. It estimates that the overall loss to the grid will be 11.7 percent of its total daily solar generation.
Cutcher said that this would amount to a loss of 16.9 gigawatt-hours—enough to power 1.69 billion LED lightbulbs—but that further solar projects coming online before April "makes it likely this number could be higher."
ERCOT's own projections, published on March 7, suggest solar output would drop from 99.2 percent just after noon on April 8 to 7.6 percent at 1:40 p.m.
While the eclipse is expected to affect power generation in other regions, Texas's power grid has a larger proportion of its supply generated by solar power, whereas for grid operators in New York or New England, solar power tends to be limited to residential buildings.
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By comparison, the New York power grid solar generation is predicted to peak at just over 3,500 megawatts, before falling to less than 250 megawatts.
ERCOT says it is planning for the eclipse and "will use available tools to balance the system" when it occurs. In the days and hours leading up to the eclipse, it will be monitoring generation and weather forecasts to ensure demand is met.
A spokesperson for ERCOT told Newsweek that it "is working on forecasting models to reflect solar generation on the grid during the eclipse" and "does not expect any grid reliability concerns during the eclipse."
ERCOT has previously suffered from strains on the power grid due to extreme weather patterns. In January, it noted "tight grid conditions" due to a cold snap increasing demand. A prolonged heat wave in the summer of 2023 threatened to do the same.
When a solar eclipse occurred in August 2017, the U.S. Department of Energy's Office of Scientific and Technical Information estimated that the U.S. lost around a quarter of its solar power generation capacity but noted that it did not cause any operational issues.
The challenge for power grip operators is not just the loss of power, but the suddenness with which it happens, which can place strain on transmission, like any large fluctuations in supply or demand.
Vahe Peroomian, professor of physics and astronomy at the University of Southern California's Dornsife College of Letters, Arts and Sciences, explained in a March 8 article for The Conversation: "Because solar power production falls quickly during the eclipse's peak, grid operators may need to tap into reserves at a rate that may strain the electrical transmission lines.
"To try to keep things running smoothly, grid operators will rely on local reserves and minimize power transfer between grids during the event."
He noted that, like other renewable energy sources, solar power was variable—only being generated when the sun was shining—and so power grids normally rely on battery storage to bridge the time difference between when solar power is generated most and when it is needed most, which could also be used in the event of an eclipse.
"ERCOT will use all available tools to maintain grid reliability and will continue to monitor conditions and keep the public informed through our communications channels," the spokesperson said.
Update 3/18/2024, 9:30 a.m. ET: This article was updated to include comment from an ERCOT spokesperson.
Update 3/19/24 7:10 a.m. ET: The headline was changed.
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