ERCOT Report Shows Increasing Reserves in Coming Years

Accelerated utility-scale solar growth boosts reserve margins.

New generation resources, including a significant amount of utility-scale solar, continue to be added to the ERCOT region at a rapid pace, resulting in higher planning reserve margins over the next several years.

ERCOT today released its December Capacity, Demand and Reserves (CDR) Report, which includes planning reserve margins for the next five years. The planning reserve margin for summer 2021 is forecasted to be 15.5%, based on resource updates provided to ERCOT from generation developers and an updated peak demand forecast. This is down 1.8% from what was reported in the May CDR due to solar and wind project delays and cancellations. Between 2022 and 2025, the planning reserve margin is expected to reach 25-27%.

“In 2018 and 2019, ERCOT experienced historically-low planning reserve margins due to plant retirements,” said ERCOT President and CEO Bill Magness. “These business cycles of retirements and new investments are expected in the ERCOT market,and it is ERCOT’s job to maintain reliable electric service through the various changing conditions.” Any changes to generation resources will be accounted for in future CDR reports.

The ERCOT region continues to see growth in customer demand, and will be incorporating demand served by Lubbock Power and Light beginning in June 2021. The forecasted peak demand for summer 2021 is 77,244 MW, and was calculated using revised economic data released by Moody’s Analytics in August. ERCOT’s current system-wide peak demand record is 74,820 MW, set on Aug. 12, 2019, between 4 and 5 p.m.

ERCOT has seen a significant increase in utility-scale solar resources, and based on the grid operator’s current interconnection queue for new generation projects, this trend is expected to continue over the next several years.

The grid operator is also seeing continued and accelerated growth in rooftop solar projects. In response, ERCOT included its first, separate rooftop solar PV forecast in the CDR. The forecast was created to show the incremental capacity growth beyond the historical growth trend reflected in the load forecast.

Based on preliminary data from generation owners, planned resources expected to be available by summer 2021 have a summer-rated capacity of 5,620 MW. This includes 816 MW of gas-fired resources, 1,765 MW of wind resources and 3,039 MW of utility-scale solar resources. An additional 9,273 MW of summer-rated solar capacity is expected to be added by June 2022.

Resources totaling 1,917 MW of installed capacity have been approved by ERCOT for commercial operations since the May CDR, and a total of 12,525 MW of installed capacity became eligible for inclusion in the CDR.

While there are only a small number of battery facilities on the ERCOT system at this time, there are a significant number of battery projects in the interconnection queue. Through the Battery Energy Storage Task Force, ERCOT has worked with stakeholders to develop new market rules for integrating these resources into the ERCOT system. The next step will be to study operational data for existing batteries in order to better understand their contributions during peak hours so their capacity can be appropriately accounted for in future CDR reports.

ERCOT’s next Seasonal Assessment of Resource Adequacy will be released in March 2021, along with a preliminary summer weather assessment that considers drought conditions in Texas.As ERCOT prepares the summer assessment, it is mindful of the accelerating pace of drought in Texas, which could significantly affect summer weather and demand for electricity. The mid-year CDR report will be released in May 2021.

Background on the CDR report

The CDR report includes a look forward at all currently operational and planned resource capacity as reported to ERCOT by resource developers and owners. It provides annual projections of ERCOT’s planning reserve margins for the summer and winter seasons. The planning reserve margin is the difference between the total generation available in the ERCOT system and the forecasted firm peak demand, with the difference expressed as a percentage of the forecasted firm peak demand.


ERCOT, the Electric Reliability Council of Texas, manages the flow of electric power to more than 26 million Texas customers, representing about 90 percent of the state’s electric load. As the Independent System Operator for the region, ERCOT schedules power on an electric grid that connects more than 46,500 miles of transmission lines and 680+ generation units. ERCOT also performs financial settlement for the competitive wholesale bulk-power market and administers retail switching for more than 8 million premises in competitive choice areas. ERCOT is a membership-based 501(c)(4) nonprofit corporation, governed by a board of directors and subject to oversight by the Public Utility Commission of Texas and the Texas Legislature.

Source: ERCOT
Media Contact: Leslie Sopko, (512) 779-8345,