ERCOT has met record demand in recent summers with only single-digit planning reserve margins. Thanks to the apparently never-ending stream of renewable projects, that margin will climb to 15.5% in 2021 and 27.3% the year after, where it will stay for the foreseeable future.

“It’s a slightly different situation, isn’t it?” Pete Warnken, the grid operator’s manager of resource adequacy, said during a media conference call Wednesday. “It’s cyclical. Boom or bust.”

The Texas grid operator said that according to its latest capacity, demand and reserves (CDR) report, generator owners have added 5.6 GW of summer-rated capacity for 2021, which includes more than 3 GW of utility-scale solar resources and 1.8 GW of wind resources. Another 9.3 GW of summer-rated solar capacity is expected to be added by June 2022, further cementing the state’s status as a solar powerhouse.

Warnken said ERCOT this year has more than doubled the solar capacity brought online in 2018-2019. “Certainly, that’s going to continue in 2022 and 2023,” he said.

Charlie Hemmeline, executive director of the Texas Solar Power Association, said during the Texas Energy Summit last month that solar developers in the state had expected 2020 to be their best year yet — an expectation that proved too strong following the COVID-19 pandemic.

“There’s a giant solar resource here. The demand has never been better,” Hemmeline said.

The grid operator is also seeing accelerated growth in rooftop solar projects. It included its first separate rooftop solar PV forecast in the CDR to show the incremental capacity growth beyond the historical growth trend reflected in the load forecast.

The additional solar and wind capacity has helped negate the effects of fossil fuel retirements. Just last May, ERCOT’s CDR projected planning reserve margins of 19.7% in 2022, dropping to 14.1% in 2025. The grid operator now foresees a 25.4% reserve margin in 2025.

ERCOT’s footprint continues to see growth in customer demand. Using revised economic data released by Moody’s Analytics in August, staff are forecasting a 2021 summer peak of 77.2 GW. That would smash the peak demand record of 74.8 GW set in 2019.

This June, ERCOT will also begin serving some 470 MW of Lubbock Power and Light’s load. (See Texas PUC Approves LP&L Integration Project.)

The grid operator expects to have 86.8 GW of capacity available to meet summer demand next year. Capacity is expected to jump to 97.6 GW in 2022 and flirt with 100 GW in 2025, when peak demand is expected to hit 82.1 GW.