On 22 June 2026, the European Union Agency for the Cooperation of Energy Regulators (ACER) adopted Decision No 08/2026 approving the first amendment to the Regional Coordination Centre (RCC) Regional Sizing of Reserve Capacity Methodology. The decision, published on 24 June 2026, follows a proposal submitted by the European Network of Transmission System Operators for Electricity (ENTSO-E) on 25 March 2026, and aims to refine the methodology for determining reserve capacity needs across system operation regions.
The original methodology was approved by ACER on 19 July 2023 under Decision No 12/2023. Under Article 3(2) of that methodology, transmission system operators (TSOs) within each system operation region, supported by the relevant RCCs, must determine specific parameters for implementation. Based on these parameters, ENTSO-E proposes amendments for ACER approval. The amendment process is governed by Article 27 of Regulation (EU) 2019/943 on the internal market for electricity, which gives ACER three months to approve or amend ENTSO-E proposals.
Between 25 March and 21 May 2026, ACER held discussions with ENTSO-E, RCCs, all TSOs, and national regulatory authorities, including sessions during ACER's Electricity Working Group on 25 March and the Electricity Balancing Task Force on 16 April. The Board of Regulators delivered a favourable opinion on 17 June 2026. The decision includes an annex setting out the amended methodology as approved, and a consolidated version for informational purposes.
The amendment impacts TSOs and RCCs, which must apply the updated methodology for regional reserve sizing, potentially altering operational coordination and cost allocation. National regulatory authorities will oversee compliance, while electricity consumers may see indirect effects on system reliability and balancing costs. The decision does not introduce major shifts but refines technical parameters based on operational experience since 2023.