A full solar eclipse on April 8 will briefly but fully obscure sunlight to utility-scale solar generation facilities from Texas through Maine with a combined 6.5 GW of capacity, the Energy Information Administration said on April 5.
In addition, the eclipse will partially block sunlight to facilities with a combined 84.8 GW of capacity in an even larger swath of the U.S. around peak solar generating time.
“Solar-powered generators centered in the path of totality — where the moon will completely obscure the sun — will be affected the most because the moon will block all direct sunlight for more than four minutes. The partial eclipse could limit the sunlight in the path of totality for more than two hours. Areas around the path of totality will have varying levels of diminished solar generation during the eclipse,” EIA said.
It noted that a number of grid operators have released plans for how they plan to deal with the change in solar generation during the eclipse.
Eclipse Will Challenge Grids in Two Ways
The solar eclipse will challenge electricity grids in two ways, EIA said.
First, utility-scale solar generation of 1 megawatt or greater, “much of which is managed by balancing authorities, will have lower solar output along the path of the eclipse. System operators will respond by dispatching other generating resources.”
Homes and businesses that use small-scale solar “will also require more electricity from the grid than usual. Because small-scale solar is not managed by balancing authorities, the increased demand from these homes and businesses will likely appear as an overall power demand increase on the electricity grid rather than a shift from solar power to grid power,” EIA said.
Second, battery storage is a significant factor in the grid’s response to the eclipse, EIA noted. In the United States, there are 15.4 GW of battery storage. During the last solar eclipse, in 2017, only 0.6 GW of battery storage was operating in the United States.
According to EIA, Texas will lose the most solar generating capacity because most of the state is in the path that will lose 90%–99% of solar power during the eclipse.
Although most of California is in the 40%–59% partial reduction range, the state’s significant use of utility-scale and small-scale solar capacity makes the eclipse’s impact more significant, EIA said.
“Florida is noteworthy because when the eclipse occurs, solar generation is likely to be the second-leading energy source on the system and account for about 20% of the state’s total generation.”
According to EIA, solar electricity capacity has grown rapidly in the U.S. since the 2017 solar eclipse, especially in Texas.
Utility-scale solar capacity was 8% (91 GW) of total U.S. capacity at the end of 2023.
Solar power can be the third-largest source of midday generation in the United States during the spring and summer months. Solar is the largest source of midday generation in California and the second-largest source of midday generation in Texas, Florida, other parts of the East Coast, and in the Southwest.
“Even with the eclipse, we still expect solar generation to be the third-largest contributor of electricity in the United States on April 8, behind natural gas and nuclear,” EIA said.
