We’ve been checking in periodically with the ERCOT battery fleet and its participation in the ancillary service markets, as well as the real-time and day-ahead energy markets. Last March, we pinpointed the start of this year as a turning point for the fleet in ‘The Case of the Missing Dispatch’. By early 2024, we predicted the fleet would saturate the ancillary service market, find more revenue opportunities in capturing day-ahead and real-time energy arbitrage, and dispatch more to the grid. In March of this year, we declared the case cracked in another battery report titled ‘Cracking the ERCOT Battery Dispatch Case’. In this report, we’ll check in on the same indicators now that the first half of the year is in the rearview and look at some insights from our June ERCOT Monthly Battery Dashboard.

The ERCOT fleet has made big gains in capacity so far this year and is now large enough to provide all required megawatts for the ancillary services they could potentially participate in. The figure below displays the average required megawatts for RegUp (green), RRS (yellow), and ECRS (blue). Note that RegDown is not included as a battery would be able to participate in RegUp and RegDown markets simultaneously. By the end of 2023, our estimate for the fleet capacity was 3.5 GW. This meant the fleet could provide all the megawatts ERCOT needed for RegUp and RRS. ECRS was introduced last summer, and while its requirements make it more complicated for batteries to participate in, they are able provide that service. (For more information on how we see batteries participating in ECRS, check out ‘Updates on ECRS’.) As of June, our estimated fleet capacity of 4.7 GW has surpassed the required megawatts for RegUp, RRS, and ECRS combined. This fleet capacity uses EIA data and if anything, is potentially an underestimate of the actual fleet capacity.

Figure 1 | ERCOT Battery Fleet Capacity and Required Regulation Quantities