Texas may be known for its oil and natural gas, but with temperatures breaching 100F (38C) across the state for a full two weeks, it’s been wind and solar power that helped keep residents cool.

The heat wave, which came unusually early this year, is expected to fuel record power demand again Wednesday, the third day the state’s grid has borne the strain. Cities like Houston, Dallas and Austin have sweat through record temperatures, and even the evenings bring little relief.

Unlike the 2021 winter freeze that saw millions of people lose power and some 200 deaths, this summer heat wave has resulted in no widespread outages.

“We’ve seen record demand, but we’ve also got quite a bit of wind and solar producing,” said Joshua Rhodes, an energy research scientist at the University of Texas at Austin. “While demand is really high, so is supply.”

Green-power sources contributed about a third of total output Tuesday. In just three years, oil-rich Texas has added the solar equivalent of 12 nuclear reactors, putting it on the cusp of surpassing California as the top producer of electricity from solar farms.

Renewables’ prominent role in the grid’s stability over the past two weeks casts doubt on some Republican politicians’ claims that heavy reliance on solar and wind was leaving the network vulnerable to disruption.

Read More: GOP Fights Solar Boom That’s Made Texas King of Clean Energy

Texas grid officials have only had to ask consumers to conserve energy on one day since extreme temperatures descended on the Lone Star State, prompting heat advisories and lots of hand wringing about the grid’s stability.

Concerns stem from the storm two years ago that froze power plants and triggered widespread blackouts for days. Some Texas Republicans, aligned with the state’s powerful oil and gas industries, have pushed to incentivize fossil-fuel power generation while blaming the state’s increasing reliance on renewables for leading to the instability of the power system. Studies have found that failures at natural-gas plants were the bigger culprit.

13 Deaths

At one point Wednesday morning, wind turbines were generating more power across the state than any other source, including natural gas. Despite the growth in renewables, gas fired power plants are still generally providing the bulk of supply for the Texas grid.

While the lights have stayed on, officials have attributed at least 13 deaths in Texas to the heat, according to a tally by the Associated Press. The Texas Tribune reported that during the current hot spell at least nine inmates died of heart attacks or unknown causes in prisons that lack air conditioning. More than two-thirds of the state’s prisons don’t have air conditioning in most living areas, the report said.

Read More: America’s Biggest Power Source Wasn’t Built for Extreme Weather

The heat wave also comes as Governor Greg Abbott moves to undermine local laws that require rest breaks for construction workers. A recently signed bill limits cities’ ability to create their own rules — including the rest mandated in Austin and Dallas — as of Sept. 1.

“The same state legislature that so fiercely defends our sovereignty against federal encroachment is now seeking to undermine local control,” said George Fuller, the mayor of McKinney, a city near Dallas.

While forecasts call for the extreme temperatures to moderate in Texas over coming days, the state — and the rest of the country — isn’t out of the woods yet.

The heat wave is forecast to spread across the central and southern US, a cause for worry since federal regulators have warned that large swaths of the country’s power grid are at risk of blackouts during times of extreme heat. Severe weather including deadly tornadoes already have cut power to hundreds of thousands of Americans this month.

--With assistance from Joe Carroll.