Sign In or Create an Account.

By continuing, you agree to the Terms of Service and acknowledge our Privacy Policy


Saturday’s Eclipse Will Wreak Havoc on America’s Solar Power

Ever wonder how an eclipse affects solar? We’re about to find out.

An annular eclipse.
Heatmap Illustration/Getty Images

The annular solar eclipse Saturday morning will darken a stripe of the United States stretching from Texas’s Gulf Coast to the Four Corners to the northwest corner of California and Southern and Central Oregon. A broader stretch around this already massive area will experience 65 percent to 90 percent of that darkness.

NASA eclipse mapNASA

While Saturday’s solar eclipse will only be partial — with 90 percent obscuration — compared to the full eclipse in 2017, the effect on electricity will be greater. That’s because of the spectacular growth of solar power.

The eclipse’s swath includes a huge portion of the United States’ solar power, especially in Texas and California, which will affect these areas’ electric grids. ERCOT, the energy market that covers nearly all of Texas, projected that its power capacity will dip from 79.2 gigawatts at 10 a.m. CT to 71.6 gigawatts at 11 a.m., whereas on Sunday capacity is projected to go from 77.6 gigawatts at 9 a.m. to 78.6 gigawatts at 11 a.m. ERCOT said in a statement that it anticipates the eclipse affecting solar output from 10:15 a.m. to 1:40 p.m..

Solar eclipses aren’t new, of course, but the amount of solar power, especially in the western United States, has grown tremendously since 2017. Back then, California’s grid had 10 gigawatts of solar installed and 5.8 gigawatts on rooftops; now it’s 16.5 gigawatts installed on the grid and 14.4 gigawatts of solar on the roofs of homes and businesses.

In California, the state’s system operator projected that solar output could fall by a whopping 9.7 gigawatts at the eclipse’s maximum, assuming the sky is clear before the eclipse, reducing solar capacity by about a quarter. That’s enough generation to power some 2.7 million homes disappearing off the grid.

As the eclipse ends, solar production will surge by 10.8 gigawatts, which the California Independent System Operator estimated was 10 times the normal rate that solar ramps up at as the sun rises and moves across the sky.

“An eclipse is a unique and rare event that captures the public imagination and requires a lot of coordination,” CAISO said in a statement.

Matthew Zeitlin profile image

Matthew Zeitlin

Matthew is a correspondent at Heatmap. Previously he was an economics reporter at Grid, where he covered macroeconomics and energy, and a business reporter at BuzzFeed News, where he covered finance. He has written for The New York Times, the Guardian, Barron's, and New York Magazine.


The Electrolyzer Tech Business Is Booming

A couple major manufacturers just scored big sources of new capital.

Heatmap Illustration/Screenshot/YouTube

While the latest hydrogen hype cycle may be waning, investment in the fundamental technologies needed to power the green hydrogen economy is holding strong. This past week, two major players in the space secured significant funding: $100 million in credit financing for Massachusetts-based Electric Hydrogen and $111 million for the Australian startup Hysata’s Series B round. Both companies manufacture electrolyzers, the clean energy-powered devices that produce green hydrogen by splitting water molecules apart.

“There is greater clarity in the marketplace now generally about what's required, what it takes to build projects, what it takes to actually get product out there,” Patrick Molloy, a principal at the energy think tank RMI, told me. These investments show that the hydrogen industry is moving beyond the hubris and getting practical about scaling up, he said. “It bodes well for projects coming through the pipeline. It bodes well for the role and the value of this technology stream as we move towards deployment.”

Keep reading...Show less

Biden Takes a Side in the Solar Industry’s Family Feud

The administration is expanding tariffs to include a type of solar modules popular in utility-scale installations.

Solar panels.
Heatmap Illustration/Getty Images

The Biden administration continued its campaign to support domestic green energy manufacturing via trade policy on Thursday, this time by expanding existing solar panel tariffs to include the popular two-sided modules used in many utility-scale solar installations.

With this move, the Biden administration is decisively intervening in the solar industry’s raging feud on the side of the adolescent-but-quickly-maturing (thanks, in part, to generous government support) domestic solar manufacturing industry. On the other side is the more established solar development, installation, and financing industry, which tends to support the widespread availability of cheaper solar components, even if they come from China or Chinese-owned companies in Southeast Asia.

Keep reading...Show less

Vermont Is One Signature Away From a Climate Superfund

The state’s Republican governor has a decision to make.

Vermont flooding.
Heatmap Illustration/Getty Images

A first-of-its-kind attempt to make fossil fuel companies pay for climate damages is nearly through the finish line in Vermont. Both branches of the state legislature voted to pass the Climate Superfund Act last week, which would hit oil and gas companies with a bill for the costs of addressing, avoiding, and adapting to a world made warmer by oil and gas-related carbon emissions.

The bill now heads to the desk of Republican Governor Phil Scott, who has not said whether he will sign it. If he vetoes it, however, there’s enough support in the legislature to override his decision, Martin LaLonde, a representative from South Burlington and lead sponsor of the bill, told me. “It's a matter of making sure everybody shows up,” he said.

Keep reading...Show less