Commercially operational BESS capacity in ERCOT reached 18.7 GW and 33.4 GWh at the end of September 2026.

2.2 GW of new capacity was fully approved for commercial operation in Q3, the most in any quarter ever, despite annualized revenues in 2026 for the average battery in ERCOT landing at $24/kW-year through August 16, according to Modo Energy's ERCOT BESS index.

That compares with $28/kW-year in 2025 and $193/kW-year in 2023.

However, while quarterly additions are as high as ever, the longer-run annual trend tells a different story. Additions doubled from 2.0 GW in 2023 to 3.9 GW in 2024, then rose 55% to 6.05 GW in 2025. In 2026, they are on course for around 6 GW, just like in 2025. Rather than new additions exceeding the prior year, they are starting to plateau.

The pipeline for 2027 points lower. Total rated power of projects with an interconnection agreement and posted financial security stands at 5.9 GW for 2027, down from 9.7 GW listed for 2025 two years ago. Based on past delivery rates, 2027 additions are likely to be somewhere in the range of 3.7 to 4.8 GW.

Key takeaways

• A record 2.2 GW reached commercial operation in Q3, even as average battery revenues fell to $24/kW-year. Most of these projects committed two to three years ago, in a far stronger market.
• Two-hour systems now dominate new builds, making up 90% of Q3 additions.
• Houston had its biggest quarter yet, taking 57% of new capacity, though North still holds the most.
• Only 2.4 GW of new BESS entered ERCOT's queue in Q3, the lowest quarter since 2020.

A record quarter inside a flattening year

Twenty BESS units across 18 sites reached commercial operation in Q3 2026, adding 2.2 GW and 4.6 GWh. That beats the previous quarterly record of 2.05 GW, set in Q3 2025.

Developers have settled on two-hour systems. Units of 1.5 to 2.5 hours supplied 1.94 GW, 90% of Q3 additions, and units under 1.5 hours supplied 0.09 GW. In Q4 2024, units under 1.5 hours had supplied 1.12 GW, 74% of that quarter. Q3 additions averaged 2.1 hours.

Large sites supplied almost all of the quarter's capacity. Eleven units above 100 MW added 1.9 GW. Among asset owners, Lydian Energy saw the largest amount of capacity reach commercial operations, with 564 MW across Headcamp, Pintail Pass and Soda Lake 1. Greenflash added 409 MW at Sahara and Sahara 2. Orsted's Buffalo Creek, Cypress Creek's Rhapsody and Alpha Omega Power's Vertus also each added more than 200 MW.

Most of these projects committed in a stronger market. Projects that reached commercial operations this quarter signed their interconnection agreements a median 2.8 years before COD. 1.3 GW of the 2.2 GW completed this quarter signed in 2023 or earlier, when the ME BESS ERCOT index averaged $193/kW-year. Developers that reach commercial operation today are delivering on decisions made two to three years ago.

Year to date, 4.7 GW of storage has reached COD in ERCOT, against 4.2 GW at the same point in 2025. However, developers added another 1.9 GW in Q4 2025, so 2026 needs another near-record quarter to result in more installations than 2025.

Commissioning resources will decide where 2026 lands. Twenty-nine batteries totaling 2.77 GW are synchronized but lack full commercial-ops approval. Eleven of them, 1.41 GW, are synchronized and have reached the stage of being capable of dispatch up to their full rated power in the real-time market.

They include Intersect Power's Quantum and Solace (643 MW), RWE's Cartwheel 1, Crowned Heron 1 and Stoneridge (410 MW), and NextEra's Blue Summit II and Roadrunner Crossing (301 MW).

Nine more, 0.96 GW, are in earlier testing phases, but not fully available for dispatch. The other nine units, 0.40 GW, have received approval to synchronize but not yet begun to be dispatched at all. This analysis counts the testing and synchronized-only units toward 2027.

If every unit already dispatching normally in the real-time market gained full commercial-ops approval in Q4, 2026 would reach about 6.2 GW, level with 2025.

Ask Ko, free

Ko is Modo Energy's AI analyst, and anyone can try it free. Try prompts like:

• Rank ERCOT BESS owners by operational capacity, and show how much each added in Q3 2026.
• Which ERCOT batteries reached commercial operation between July and September 2026, and who owns and optimizes them?
• Which ERCOT batteries earned the most revenue per MW over the past year, and who owns and operates them?

Houston had its biggest quarter, but North still leads

Houston added 1.22 GW in Q3, 57% of the quarter's total, and rose from 2.9 GW to 4.2 GW.