Sign In or Create an Account.

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

Climate

The Eclipse Was a 3-Hour Boon for Gas, Batteries, and Hydro

What happens to the grid when the sun goes away?

An eclipse and solar panels.
Heatmap Illustration/Getty Images

Early April is typically a kind of goldilocks moment for solar power. Days are getting longer but the weather is still mild, meaning that higher solar power generation isn’t entirely eaten up by increased demand due to air conditioning.

But that all depends on the sun actually shining.

Monday’s solar eclipse took a big chunk of power off the grid. Since 2017’s eclipse, solar power generation has increased substantially, both locally (think rooftops) and at utility scale (think massive fields of solar panels). In 2017, the U.S. had around 35 gigawatts of utility-scale solar capacity, a figure that had increased to an estimated 95 gigawatts by the end of 2023.

While total solar eclipses are rare (the next one to hit the lower 48 isn’t expected until 2044), the challenges they present to grid operators may be part of the new normal. With vastly expanded renewable energy generation comes a greater degree of unpredictability, as a growing a portion of the generation fleet can drop off the grid due to weather and climate conditions — like, say, clouds of smoke from a wildfire — that cannot be precisely predicted by 17th century science.

Grid operators were confident they’d be able to manage through the eclipse without any reliability issues, and what actually transpired mostly confirmed their forecasts. In Texas, solar power production shrunk from around 13.5 gigawatts at noon, making up 27% of the grid’s electricity supply, to a mere 0.8 gigawatts at 1:30 p.m. Things did not go as well for the Midcontinent Independent System Operator, however, which includes a swath of the middle of the country from Minnesota to Indiana to Louisiana. Solar output was estimated to drop from around 4 gigawatts at 1 p.m. Central time to 2 gigawatts an hour later, according to Grid Status. Instead, output dropped to around 300 megawatts, causing real-time prices for power on the grid to spike.

ERCOT energy mix chart.ERCOT’s fuel mix from Monday, April 8, including during the solar eclipse.ERCOT

Overall, the U.S. Energy Information Administration estimated that some 6,500 megawatts of solar generation capacity would be fully obscured during the eclipse, which would “partially block sunlight to facilities with a combined 84.8 GW of capacity in an even larger swath of the United States around peak solar generating time.” Some 40 gigawatts may have come off the grid, enough power for about 28 million homes, according to a release from Solcast, a solar forecasting company.

By comparison, during the 2017 eclipse, solar power loss at its peak was between 4 and 6.5 gigawatts and the total loss of power was around 11 gigawatts, according to the National Renewable Energy Laboratory.

In states like Texas, the main effect was on utility-scale production of solar, but in the Northeast and parts of the mid-Atlantic and Midwest, there was also a related problem: Behind-the-meter solar fell off, too, thus requiring the homes and businesses that generate power for themselves in the middle of the day to get more power from the grid, increasing demand on the grid at a time of low supply.

New England has seen immense growth in rooftop solar, and solar production was expected to fall by “thousands” of megawatts, according to ISO New England, while the New York Independent System Operators expected to lose 700 megawatts of behind the meter solar.

During the 2017 eclipse, the National Renewable Energy Laboratory found that “the burden of compensating for the lost energy from solar generators fell to the thermal fleet,” i.e. natural gas, along with some increases in coal and hydropower production.

Since then, the coal fleet has shrunk, thus putting more of the burden of responding to Monday’s eclipse onto gas and hydro, but the basic logic still applies. “Grid operators are expected to rely on natural gas to ensure stability and meet the household demand spike across national grids, as was done during the previous eclipse in 2023 in California and Texas,” according to Solcast. As the sun was dimming in Texas, natural gas generation rose from 18.7 gigawatts to 27.5 gigawatts.

Something else that’s changed since 2017: batteries. By the end of 2023, Texas had installed 5.6 gigawatts of grid storage, most of it providing so-called “ancillary services,” power sources that can respond quickly to immediate needs. ERCOT, the electricity market that covers most of Texas, said in a presentation back in February that it would rely on these ancillary tools to get through the eclipse, and once again, it was right. Power from batteries on the grid got up 1.4 gigawatts during the eclipse.

Editor’s note: This story has been updated to reflect the actual effects of the eclipse on U.S. power generation.

Blue

You’re out of free articles.

Subscribe today to experience Heatmap’s expert analysis 
of climate change, clean energy, and sustainability.
To continue reading
Create a free account or sign in to unlock more free articles.
or
Please enter an email address
By continuing, you agree to the Terms of Service and acknowledge our Privacy Policy
Electric Vehicles

London’s Police Cars Are Going Electric With the Help of AI

The Metropolitan Police Service signed a deal with BetterFleet to manage the complicated logistics.

A police car and a lightning bolt.
Heatmap Illustration/Getty Images

Police officers can’t be stuck waiting for their black-and-whites to recharge when an emergency call comes in. That urgency makes it especially tricky to transition their fleets away from fossil fuels and the lightning-fast gas fill-ups that get cars back on the road.

But some cities and departments have begun to make the move, aided by artificial intelligence models to manage their many vehicles and ensure electric cars can do not just the next job, but every job. Around the world, trucking companies, buses, municipal vehicles, and other huge fleets want to go electric to save money on fuel and maintenance, and they’re looking to AI to give them the confidence to take the plunge.

Keep reading...Show less
Blue
AM Briefing

A Rare Earths Civil War

On Last Energy’s milestone, California CCS, and RFK Jr. vs. microplastics

A mining truck.
Heatmap Illustration/Getty Images

Current conditions: The summerlike heat in the Northeast is set to drop by double digits as cold Canadian air blows southward, sending temperatures in Boston as low as 50 degrees Fahrenheit by Saturday • Temperatures are nearing 100 degrees in Cordoba, Spain, as Western Europe’s record-breaking heatwave continues • Juba is also nearly 100 degrees as heavy thunderstorms roll into the capital of conflict-riven South Sudan.


THE TOP FIVE

1. America’s two rare earths champions are fighting each other

Last year, in a move so bold it made Biden administration officials jealous, President Donald Trump took an equity stake in MP Materials, making the federal government the largest shareholder in the United States’ only active domestic rare earths producer. The deal became a trend, with the U.S. government taking minority ownership stakes in at least a dozen more companies that produce or process critical minerals, of which China controls the global supply. In January, USA Rare Earth, a manufacturer of rare earth magnets that aims to eventually mine and process fresh ore in Texas, became the second large rare earths-focused company in the Trump administration’s portfolio. Now America’s two champions in the war against China’s metal monopolies are instead battling each other. On Wednesday afternoon, the Financial Times reported that MP Materials had filed a lawsuit against USA Rare Earth, accusing its rival of “stealing” its technology for making the permanent magnets that go into everything from phones and electronics to electric vehicles to fighter jets. “USA Rare Earth has repeatedly failed to meet its commercial and performance targets and is now resorting to stealing technology to dig itself out,” MP Materials alleged in a complaint filed last week in Texas court. In response, USA Rare Earth said: “MP Materials’ complaint has misrepresented our company, our culture, and our people, and we will defend ourselves vigorously.”

Keep reading...Show less
Yellow
Climate Tech

Climate Tech Bets on Space

In space, no one can oppose your data center.

Solar panels in space.
Heatmap Illustration/Getty Images, Wikimedia Commons

An investment boom is exploding in outer space. Investors have thrown their backing behind space-based solar power, orbital data centers, and even extraterrestrial power grids. SpaceX is pursuing an IPO — potentially the largest the world has ever seen — in part to fund its own off-Earth data center ambitions. The Space Foundation reported that the global space economy reached $613 billion in 2024, combining commercial revenue and government funding, while PricewaterhouseCoopers estimates the sector could grow to reach $2 trillion by 2040, largely driven by private sector innovation and support.

Different though they may be, these technologies all leverage the vast unknown outside our atmosphere to monitor, manage, and optimize terrestrial energy and climate systems.

Keep reading...Show less
Blue