Operators will see a speedy loss of large loads of solar energy and the whiplash as it comes back to the grid when the eclipse ends.

The total solar eclipse will be a test of how well the country’s grid will handle an unprecedented swing in solar-power production.

Operators will have to balance a speedy loss of large loads of solar energy as well as the whiplash of that energy coming back to the grid as the eclipse runs its course.

Don’t reach for a flashlight just yet.

The eclipse will obscure the sunlight needed to generate electricity at some 1,900 utility-scale solar-power plants in the country, the Energy Information Administration said this week.

Relatively little solar-power capacity lies directly on the path of totality, or where the sun will be completely obscured by the moon, and no reliability issues are expected in the U.S.

Naturally, solar-powered generators on the path of totality will be affected the most, as the moon will block all direct sunlight for up to three minutes. The generators will also be affected to a lesser extent throughout the entire eclipse, expected to last up to three hours. Generators outside totality will be less affected, depending on how much sunlight is obscured.

During the eclipse, electricity generators in the areas obscured will have to increase output from other sources of electricity generation to make up for the decrease in solar power.

Utilities do that on a regular basis, albeit on a much smaller scale, when they reach out to “peaker” power plants to smooth out swings. Peakers, as their nickname implies, run when demand is higher, such as in the afternoon, or when the weather turns extreme. They not only prevent blackouts and brownouts but also instability in the power grid. Peakers are usually powered by natural gas.

The next eclipse over North America will occur on April 8, 2024, sweeping a diagonal southwest-northeast path across Mexico, U.S., and Canada. The next U.S. coast-to-coast eclipse is not until Aug. 12, 2045.