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Total Solar Eclipse May Briefly Impact Solar Power and the Grid


On April 8, 2024, a total solar eclipse is expected to be visible in a relatively narrow path from Mexico through the U.S. and up to Canada. A total solar eclipse occurs when the Moon is positioned directly between the Earth and the Sun such that the Moon obscures all of the Sun except its corona.  The most recent total solar eclipse on the U.S. mainland was in 2017, but, after 2024, the next total solar eclipse on the contiguous U.S. will not be until August 23, 2044.  The eclipse’s “path of totality” -- the area on which the eclipse will be a total eclipse -- is 124 miles wide, with the totality lasting from 3.5 to 4.5 minutes depending on the location.  The amount of time during which the Moon partly obscures the Sun will be about 2.5 hours at any given location.  This rare phenomenon has caused excitement as well as some level of concern about its impact or potential impact on solar power and thus on the electricity grid. 


The total solar eclipse planning of the largest regional transmission operator (RTO), PJM Interconnection, LLC (PJM), is illustrative PJM anticipates potential impacts to electricity supply and demand when the sunlight is briefly blocked on April 8th.


PJM’s March 18, 2024, News Release on this subject states in part:


PJM’s advance analysis of the weather, electricity demand and available generation supply for April 8 accounts for various scenarios as the earth falls into the moon’s shadow and helps determine how PJM dispatchers will respond in real time.


Weather is the main determining factor in the production of electricity from solar panels, as solar generation generally decreases in direct proportion to the presence of cloud cover. The eclipse will occur when solar radiation is at its highest, Michael Stewart, PJM Sr. Engineer – Load Forecasting, told PJM stakeholders in a presentation at the March 7 Operating Committee meeting.



Even under cloudy skies, PJM is preparing to observe temporary losses of at least 80–85% of the production from the approximate 8,200 MW of grid-connected solar or metered solar resources that are part of the PJM solar generation fleet in early April.

PJM is also preparing for the potential temporary loss of up to 4,800 MW of non-metered or behind-the-meter solar resources during the eclipse.

For another example, the Electric Reliability Council of Texas (ERCOT), which handles most of the Texas electric grid, which also in the path of the solar eclipse, has reported that it forecasts a sudden, brief drop in solar power. ERCOT has stated that it has been proactively modeling what to anticipate with a reduction in solar power, although they do not foresee any disruptions in service.


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