Will America’s Epic Eclipse Impact Our Electric Grid?
For about three hours on August 21st, power grid operators across the United States will be confronted with a sudden drop in available electricity, owing to the first coast-to-coast solar eclipse in nearly a century. Power disruptions are not expected, but only because measures are being taken to make up for the sudden energy shortfall. Here’s the amount of solar power the US is expecting to lose and what grid operators are going to do about it.
The last time Americans saw an eclipse like this was in 1918, and much has changed since then—especially how we get our energy. We’re in the midst of a green energy revolution, where more traditional sources like coal, gas, hydro, and nuclear are slowly being replaced by wind, solar, and geothermal. Solar in particular has taken off in the US, with total solar capacity increasing 8,500-fold in the past 17 years. Today, approximately 1.26 percent of all energy consumed in the United States comes from solar, the primary drivers being the states of California, North Carolina, Arizona, Nevada, and New Jersey.
Grid operators in the US are already familiar with solar power disruptions due to changes in cloud cover, intense, rainstorms, and seasonal shifts in the length of the day. But for a few critical hours on August 21st, the Moon is going to spoil the solar power show. Skies across the continental US will darken from 11:35 am ET to 2:30 pm ET, most prominently within the 14 states along the path of totality—the stretch along which the Moon will completely obscure the Sun. Even areas outside the path of totality will experience diminished sunlight, creating a challenge for power companies working to keep the lights on.
The eclipse may only last for a couple of minutes at any given location, but grid operators across the US are bracing for the effect.
To avoid power disruptions, grid operators will have to perform a delicate juggling act, transporting energy across the country to make up for the temporary shortfall in solar-dependent regions, while carefully monitoring the ebb and flow of available solar energy as the Moon drifts across the surface of the Sun. Thankfully, we’d had ample time to prepare—it’s not like we didn’t know this eclipse was coming.
Grid operators also have a precedent to work with: Back in 2015, a similar event happened in Europe. The solar eclipse of March 20, 2015, caused a “great deviation in the amount of solar generation that was available before, during, and post eclipse,” forcing the intense “coordination of primary, secondary, and tertiary reserves across Europe within a reduced time frame,” according to a policy brief produced by Solar Power Europe in the wake of the celestial show. In Germany, the eclipse caused solar power output to temporarily drop from 14 GW to 7 GW, compared with a 38 GW solar power capacity.
“The August 21 eclipse is a multi-state event because solar or photovoltaic resources are an increasingly significant part of the electricity generation mix throughout the United States,” said Martin J. Coyne, Communications Coordinator for North American Electric Reliability Corporation (NERC), in an interview with Gizmodo. “The capacity of solar or photovoltaic resources for generating electricity across the United States grew from five megawatts in 2000 to 42,619 MW in 2016.”
Coyne said the impact of an eclipse on the bulk power system depends on several factors, including the event’s duration and timing.
“For most states, the timing of the eclipse is when electricity demand is below the morning [between 6:00 to 9:00 am] and evening peaks [between 4:00 and 8:00 pm],” he explained. “The greatest need for grid operators to plan for the availability of additional generation are in California because it has more solar capacity than any other state and in North Carolina because the eclipse occurs there near the evening [demand] peak.”
If the eclipse occurred at the peak hour in each state, which it is not going to do, the expected impact to solar resources would be between 5,534 MW and 6,329 MW, said Coyne. For comparison, 6,000 MW is the amount of power needed to run six million homes, or a city the size of Los Angeles.