Research from the Federal Reserve Bank of Dallas shows that solar power and battery storage capacity helped stabilize Texas’ electric grid last summer.

Between June 1 and Aug. 31, solar power met nearly 25 percent of midday electricity demand within the Electric Reliability Council of Texas (ERCOT) power grid. Rising solar and battery output in ERCOT assisted Texans during a summer of triple-digit heat and record load demands, but the report fears that the state’s power load will be “pushed to its limits” soon.

The report examined how the grid performed during more demanding hours. At peak times, between 11 a.m. and 2 p.m. in the summer of 2024, solar output averaged nearly 17,000 megawatts compared with 12,000 megawatts during those hours in the previous year. Between 6 p.m. and 9 p.m., discharge from battery facilities averaged 714 megawatts in 2024 after averaging 238 megawatts for those hours in 2023. Solar and battery output have continued to grow since then, according to the report.

“Batteries made a meaningful contribution to what those shoulder periods look like and how much scarcity we get into during these peak events,” ERCOT CEO Pablo Vegas said at a board of directors conference call.

Increases in capacity from solar and battery-storage power in 2024 also eclipsed those of 2023. In 2023 ECOT added 4,570 megawatts of solar, compared to adding nearly 9,700 megawatts in 2024. Growth in battery storage capacity also increased from about 1,500 megawatts added in 2023 to more than 4,000 megawatts added in 2024. Natural gas capacity also saw increases while wind capacity dropped by about 50 percent.

Texas’ installation of utility-scale solar surpassed California’s in the spring of last year, and jumped from 1,900 megawatts in 2019 to over 20,000 megawatts in 2024 with solar meeting about 50 percent of Texas' peak power demand during some days.

While the numbers are encouraging, the report states that there could be future challenges, as more generating capacity will be required due to data center construction and broader electrification trends. The development of generating more capacity will rely on multiple factors like price signals and market conditions that invite more baseload and dispatchable generating capacity, which includes longer-duration batteries, and investment in power purchase agreements and other power arrangements by large-scale consumers, according to the report.

Additionally, peak demand during winter freezes presents challenges not seen in the summer. For example, in colder months, peak electricity demand often occurs in the early morning before solar energy is available, and it predicts that current battery storage may be insufficient to meet the demand. The analysis indicated a 50% chance of rolling outages during a cold snap similar to December 2022 and an 80% chance if conditions mirror the February 2021 deep freeze at the grid’s current state.

The report also claimed that ERCOT’s energy-only market design and new incentive structures, such as the Texas Energy Fund, do not appear to be enough to meet the predicted future magnitude and speed of load growth.

Read the full report here.