The Electric Reliability Council of Texas (ERCOT) grid, which serves about 90% of Texas’ electric load, set a new demand record this summer: 91,134 megawatts (MW) on July 22. Over the course of summer 2026, demand topped the previous record of 85,464 MW set in 2023 on 34 different days. As a previous post showed, ERCOT served every one of those hours without a statewide conservation appeal or rotating outages. This post examines some of the factors that fueled this summer’s performance as well as how the grid looks and behaves differently than in the past.
An evolving generation fleet
Between September 2015 and August 2016, the ERCOT grid generated a total of 346.9 million megawatt hours (MWh) of electric power. Ten years later, ERCOT generated 511.7 million MWh over the same period, reflecting a 47.5% increase from 2016 to 2026.
The generation fleet behind that growth has substantially evolved. As illustrated in the chart below (Figure 1), ERCOT now has a larger, more diversified generation portfolio.
Solar accounted for 50.9% of the growth in ERCOT’s primary generation over the past 10 years, growing by more than 11,000% between 2016 and 2026. Solar’s share of all ERCOT generation rose from 0.2% to 15.7% while wind’s share rose from 14.6% to 23.5%.
Batteries, which do not appear in ERCOT’s generation data before 2020, supplied 1.6% of generation in 2026 but have proven especially valuable in tight evening hours: in this summer’s 20 tightest hours — when generation supply was closest to demand — they supplied an average of 9,323 MW, nearly double the 4,932 MW in 2025. While batteries have a net negative generation profile since they use electricity to charge, they are a helpful tool for reliability because they can charge up when electric demand is low and less expensive, and provide power when the grid needs it most.
Natural gas generation also increased between 2016 and 2026, by 23.2%, although its share of total generation fell from 46.8% to 39.1%. Gas, coal and nuclear still supplied 59.1% of ERCOT’s generation in 2026, with gas the largest single source at 39.1%. They also carry the grid when solar fades: on the average summer day of 2026, gas supplied 48.3% of generation in the 8-9 p.m. hour, and gas, coal, nuclear and wind powered most of the overnight hours.
Figure 1. Wind and solar supplied 39.1% of ERCOT generation in 2026, up from 14.8% in 2016
Generation by source (million MWh), 2016 and 2026
Note: Percentages are each source’s share of the year’s generation. Battery charging is drawn below zero. Hydro, biomass and other (0.5% of generation in 2016 and 0.2% in 2026) is not shown; totals include it. Annual totals cover the 12 months from September to August, so 2016 is September 2015 through August 2016 and 2026 is September 2025 through August 2026.
Source: Texas 2036 analysis of ERCOT hourly Fuel Mix data; July-August 2026 values are ERCOT’s initial settlement as of Sept. 29, 2026
Bigger reserves
ERCOT also has more backup power ready to go. It tracks this with a measure called physical responsive capability (PRC): generation that can ramp up within minutes if needed. Lower PRC numbers indicate less reserve capability. In the grid’s most demanding hours, median PRC has grown substantially over the past decade, more than tripling between 2016 and 2025. PRC nearly doubled between 2023 and 2025 alone. Some of the increase here can be attributed to the fact ERCOT began counting batteries toward PRC in 2022. Regardless, ERCOT has operated the grid more cautiously since July 2021, and has more backup power on hand.
An “all of the above and below” grid
At the July 29, 2026, Senate Committee on Business and Commerce hearing, ERCOT CEO Pablo Vegas said the “burden and the requirement” on Texas’ thermal generation fleet (gas, coal and nuclear) remains “very, very high” during the grid’s peak periods. These thermal resources have not grown as much as renewables have over the past decade. ERCOT also noted that every resource on today’s grid helps serve Texans at different points in the day.
As Texas adds capacity to meet rising demand, policy should build on the strengths of the current portfolio and focus on additive expansion.
This summer was a reliability success story, and it showed that a balanced, diversified generation mix remains key to electric reliability. Winter brings different challenges, since demand peaks in the mornings and evenings, when solar isn’t readily available. A future post will look at how the grid performs in winter.
