ERCOT Storage Performance | May 2026

For the majority of the ERCOT’s storage fleet, May was a down month compared to April, but more or less on par with Q1. Just looking month-over-month, average revenue was 46% lower than it was in April, and DA TBx capture was down 18%. However, there were a small handful of battery assets that absolutely crushed it – with the top revenue generator earning 35% more than last month, and the top performer up 184%. 

Both top earners and performers made the majority of revenue in Real-Time (RT) energy, 76% and 72% respectively, distantly followed by RT Ancillary Services (AS), at 9% and 13%.

This is particularly interesting when you look at it in tandem with the fact that, on average, AS Up products had positive DART spreads in nearly every hour, and energy had positive DART spreads during the evening peak hours. Does this tell us that opportunity is being left on the table for more aggressive Day-Ahead (DA) strategies? It’s not quite that simple. We unpack this more below.

While May looked like most other months for most battery assets in ERCOT, a few storage units far outperformed, making ~4x the median. In fact, when you remove the top 5 earning assets from the sample, the average revenue drops by almost $0.10.

RT energy was the primary revenue driver across the fleet, making up 63% of revenue for the fleet on average, and a full 90% of revenue for the top three earners.

• Highest earning asset made $8.62/kW, while the top 50 revenue generators averaged $2.75/kW
• Median asset brought in $1.20/kW, with the fleet average higher at $1.40/kW
• RT energy made up the majority of revenue at 63%

Similar to the top earners, the top performers also made the majority of their revenue in RT energy, capturing high prices on key days. 

• Top performing asset captured 418% of its DA TBx opportunity, but only 47% of RT TBx
• Top 50 performers averaged 106% of DA TBx and 75% of RT TBx
• Median and average assets captured 64% of DA TBx, average RT TBx capture was 54%

While the top three performers blew their DA TBx opportunities out of the water, they only captured an average of 42% of their RT TBx. Lower than the fleet average (54%) – and significantly lower than the next 50 assets (77%). Taken together, these data indicate that top performing assets as measured by DA TBx capture benefitted from high RT volatility, which bolstered revenue and performance compared to DA benchmarks – but left about half of their revenue opportunity on the table.

While there were a handful of days in May solid revenue opportunity across ERCOT – May 26th was the standout in terms of fleet revenue capture. This was mainly tied to elevated RT energy and AS prices in the late evening – past what we generally think of to be peak hours. 

On the whole, ERCOT’s storage fleet brought in the most revenue on May 26 – a day with a series of high RT energy and AS price prints throughout the evening. With load high and PRC low and declining, RT energy prices popped over $100/MWh just after 7pm and stayed elevated until almost 11pm. 

The highest prices of the day hit at 10pm – past the normal evening peak – and cleared at ~$280/MWh. A second spike ($225/MWh) then hit at 10:25pm. RT AS prices were peaking at this time as well — with Non-Spin and ECRS both clearing in the $60-70/MWh range between 10 and 11pm.

Storage output peaked too early, at 8:20pm, and only ~1.5GW caught the highest prints of the day.

How did the top earner operate on May 26?

Unsurprisingly, the top revenue generator captured at least part of the RT energy spike. 

In the DAM, they bid AS throughout the morning and through the afternoon — mostly Reserves, with a little Non-Spin mixed in. They began discharging into the beginning of the RT spike, but ran out of charge by the time the night’s biggest prints hit. 

Ultimately, the battery captured 422% of the DA TBx, but only 75% of their RT TBx and made $0.45/kW on the day.

In the DAM, the top performing focused on Non-Spin and Reg Up, with a bit of ECRS throughout the morning and afternoon. This left the evening free for RTM participation. When the evening ramp hit, the operator offered into Ancillary Service – mostly ECRS with a touch of Reserves – enabling them to capture the elevated prices and generate revenue without expending nearly any energy.  

The asset ultimately made $0.09/kW but captured 673% of the DA TBx and 276% of the RT TBx.

Two different assets, at two different nodes, with two very different revenue propositions for the day. The highest earner clearly benefitted from high RT energy prices, and some energy left in the tank after the usual evening peak to capture them. The top performer (highest TBx captured) took a very honest look at their opportunity for the day and bid/managed SOC strategically to make the most of their revenue opportunity. 

*Top earners defined as highest $/kW
**Top performers defined as highest percent of DA TBx captured