​Battery energy storage revenues in ERCOT increasingly depend on energy arbitrage.

​Ancillary Service markets have saturated. As a result, owners and optimizers differentiate themselves by competing for available energy arbitrage revenues at their respective nodes.

​'Capture rate' is allows for benchmarking how well a battery capitalized on that energy arbitrage opportunity. It compares realized revenue against the theoretical maximum a battery could have earned with perfect foresight at its own node.

​In 2025, the median ERCOT battery captured 61% of its Real-Time TBX benchmark and 70% of its Day-Ahead TBX. Half of the fleet sat in a 23-point band in Real-Time (48% to 71%) and a 33-point band in Day-Ahead (58% to 91%).

​Key takeaways

• Median Real-Time capture was 61%, while Day-Ahead was 70%. This reflects more predictable peak price intervals in the Day-Ahead market.
• Half of all batteries cluster within a 23-point band in Real-Time and a 33-point band in Day-Ahead. Outliers tend to be at unusually high or low TBX nodes.
• 24 of 227 batteries beat 100% of Day-Ahead TBX in 2025; only 3 did so in Real-Time. Beating 100% requires Ancillary Service revenue, day-ahead vs real-time arbitrage, and/or a low-spread node.
• May 2025 was the high water mark for capture rates, with batteries earning more than in January 2026 despite a smaller TBX opportunity. Larger Ancillary Service revenue opportunities (particularly in Non-Spin), compared to unpredictable energy arbitrage opportunities in January, drove the difference.

​Capture rate is net revenue divided by TBX opportunity. TBX is the daily top-minus-bottom price spread, computed at each battery's own node and matched to its physical duration. A 2-hour battery is benchmarked against TB-2; a 1.5-hour battery against TB-1.5 in Real-Time and TB-2 in Day-Ahead. Net revenue is the battery's total realized energy revenue, including both day-ahead and real-time positions. See Modo Energy's Indices and Benchmarking methodology for more information on revenue calculations.

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​Why Day-Ahead capture rates run higher than Real-Time

​Day-Ahead price spreads are tighter. Real-Time carries more volatility and more scarcity events, both of which widen the daily TBX. Furthermore, minimum prices within a given day are often lower in Real-Time as more transmission congestion occurs.

The 70% Day-Ahead figure reflects a smaller denominator, not higher or lower revenues. This is because the net revenue figures used here represent all revenue earned across all wholesale revenue streams, i.e., Day-Ahead and Real-Time Energy Arbitrage, as well as Day-Ahead and Real-Time Ancillary Services.