Texas Revises State-of-Charge Rules, Battery Operators Claim Discrimination Despite Improvements in Ancillary Service Requirements.

The revised state-of-charge rules in Texas have been met with opposition from battery storage operators who believe they are discriminatory towards energy storage resources (ESRs) due to their requirement for more capacity than required when providing ancillary services. Power marketer Gridmatic stated that the amendments reduce the additional capacity required for these services but do not eliminate the requirement altogether. The rule NPRR 1186 was designed to clarify this new rule and address unintended consequences. However, battery operators argued that it was discriminatory as no other energy asset has its fuel supplies monitored or mandated in real-time. ERCOT has now revised the SOC rule to require batteries to hold only one hour of SOC for discharging ancidal service awards rather than multiple hours for different ancilliary services. The proposed 1-hour SOC rule is seen as an improvement on the December 2022 rule change, but it will still impact the ability of batteries to provide anciliary services in ERCot.