Solar bails out Texas during heat wave, but trouble looms

By Benjamin Storrow | 06/26/2023 06:18 AM EDT

The North American Electric Reliability Corp. estimates Texas has added about 4.4 gigawatts of solar capacity since last summer.

James Hand wipes sweat from his face while overseeing a parking lot asphalt resurfacing job.

James Hand wipes sweat from his face while overseeing a parking lot asphalt resurfacing job last week in Richardson, Texas. LM Otero/AP Photo

Live by the sun, die by the sun.

So it goes in Texas, where a surge in solar power generation is helping the state’s primary grid operator navigate an ongoing and stifling heat wave.

Yet, in spite of the sun-powered boost, analysts say the state’s electric grid remains unprepared for a warming climate where intense heat waves will become more frequent and severe.


The last few days have offered a preview of this hotter future. The current heat wave has shattered temperature records in many cities and reached as high as 118 degrees Fahrenheit along the Mexican border. The broiling conditions are expected to continue this week.

“We learned that climate change isn’t messing around,” said Alison Silverstein, a Texas-based energy consultant who authored a high-profile Department of Energy report on the reliability of the country’s electric system in 2018.

“This kind of heat dome and long-lasting extreme heat conditions are not anything we have seen before in Texas, and yet they are happening more and more often,” Silverstein added. “We cannot change our built infrastructure fast enough.”

Texas’ grid has been at the center of national debate over the country’s transition to cleaner electricity sources, pitting the need to reduce planet-warming pollution against the necessity of keeping on the lights.

A powerful winter storm in 2021 led to widespread power outages in much of Texas. Republicans and fossil fuel interests sought to blame renewables. Democrats and environmentalists pointed to failures at gas plants and the pipelines that serve them.

The debate often has failed to reflect the real cause of the outages. Texas power plants and gas infrastructure are simply not winterized to withstand extreme cold, a Federal Energy Regulatory Commission report found. Power plants farther north fared much better, even though they experienced colder temperatures.

But that has done little to quell the political debate. This year, Republican lawmakers passed a bill designed to encourage the build-out of natural gas and pushed legislation that would have made it harder to pass permits and connect renewable facilities to the grid. The bill passed the Senate, but ultimately died in the House.

The recent heat wave arrived against that backdrop, with solar coming to the rescue as temperatures across the state rose. The Electric Reliability Council of Texas, the grid operator serving most of the state, issued its first voluntary conservation notice of the year Tuesday.

ERCOT did not reach emergency conditions last week.

“On most of our days, we’re getting close to 20 percent or more from renewables, particularly at peak,” Silverstein said. “That is a lot of solar and wind, and stabilizing prices and shielding us from our vulnerability to dispatchable resources, many of which are older, dropping out and causing risky grid reliability events.”

The North American Electric Reliability Corp. estimates Texas has added about 4.4 gigawatts of solar capacity since last summer, resulting in a lot more electricity during summer heat waves.

About 15 percent of ERCOT’s power generation came from solar alone during most afternoon hours, often making solar the second-largest source of electricity production after natural gas, according to Grid Status, a website that aggregates electricity data from grid operators around the country.

The solar boost is important for two reasons. ERCOT reported 10G W of power plant outages as of Saturday morning, or slightly less than the 11 GW of outages that the grid operator’s summer planning scenarios describe as an extreme scenario. The largest outages were reported at a nuclear plant and two coal facilities, which were running at reduced levels through Wednesday, according to the most recent ERCOT data.

ERCOT did not respond to a request for comment.

Solar has helped fill that gap, especially at critical times of the day. Solar generation tends to be its highest during the height of the day, when electricity demand rises as Texans seek the relief of their air conditioners.

“That made the difference between simply needing a voluntary conservation call and what would have been emergency conditions without those solar farms and blackouts,” said Dan Cohan, a professor who studies the power sector at Rice University in Houston. “ERCOT is working with a bigger buffer than it’s had in recent years.”

Yet the heat wave also underscored the limits of solar’s abilities. Electricity demand last week peaked at more than 79 GW on Monday around 5 p.m., when solar output was falling, according to U.S. Energy Information Administration data. The second- and third-highest weekly peaks occurred Tuesday at 5 p.m. and 6 p.m., EIA data shows.

The dynamic points to a change in the way the grid is operated, analysts said. Where grid operators once planned to meet peak power demand earlier in the day, now they need to plan for the evening hours when temperatures are still high but solar output wanes. NERC identified 8 p.m. as ERCOT’s riskiest hour in its summer reliability assessment.

Other clean energy technologies can help fill the gap during those hours, analysts said. Texas wind generation, which drops during the heat of the day, tends to rise in the evening. Short-duration lithium batteries can help, too. Texas has installed 2.3 GW of battery capacity, according to EIA data. That is the second most in the nation, but far less than the 4.9 GW of battery capacity installed in California.

The combination of solar and batteries helped California weather a brutal heat wave at the end of last summer. But the Golden State also was buffeted by its energy efficiency and demand management measures, analysts said. A text message from the California Independent System Operator asking residents to reduce their electricity consumption was widely credited with preventing a blackout.

Texas has sought to increase the reliability of its grid by building more natural gas. But some analysts said it would be cheaper and more effective for the state to implement better demand management and energy efficiency strategies.

“I’m positive that if we don’t do that, we’re headed toward outages at some point here,” said Doug Lewin, a Texas energy consultant who authors a newsletter about the state’s power grid. “We need to update our thinking about solar and storage and what they mean for the system. But even more importantly, we need to update our thinking about demand and how we manage the peak more effectively.”

The state can expect to see more of the type of weather it has experienced this past week, said Andrew Dessler, a professor of atmospheric science at Texas A&M University.

A heat dome is a high-pressure system that acts like a lid on a pot, baking the earth beneath it. Many scientists have pointed to a 2021 heat dome that smothered the Pacific Northwest as evidence of a changing climate. The temperatures during that event were so far outside the historical record and the calculations of climate models as to be almost statistically impossible.

The temperatures experienced by Texas so far this summer are not quite that extreme by state historical standards, Dessler said. But the stifling heat is a sign of what the state can expect going forward, he said.

“One lesson is this is what’s happening with 1 degree Celsius of global average warming. And we’re on track for 3 degrees,” Dessler said. “I tell my students you’re going to live through this. If we don’t do something, the future is 3 degrees.”