ACER EU Energy Markets Brief

Headline

ACER amends day-ahead and long-term capacity calculation methodologies for the Core electricity capacity calculation region

Executive Summary

ACER has adopted two decisions amending the day-ahead and long-term capacity calculation methodologies for the Core capacity calculation region. The decisions update the technical framework governing cross-border electricity capacity allocation across the Core CCR, which spans fifteen EU member states.

Bottom Line

The two ACER decisions bind transmission system operators across the Core CCR to amended capacity calculation methodologies for both the day-ahead and long-term timeframes. The long-term extension of flow-based calculation is the structural change: it aligns the long-term horizon with the day-ahead framework already in place and alters the technical basis on which cross-border capacity is determined and offered. Market participants holding or acquiring long-term transmission rights in the Core CCR operate under a revised capacity calculation foundation as of these decisions.

Key Regulatory Signals

• Binding Methodology Changes for Core CCR Transmission System Operators: Transmission system operators within the Core capacity calculation region must implement the amended day-ahead and long-term flow-based methodologies. These operators carry direct compliance obligations under the revised decisions, requiring updates to capacity calculation processes and coordinated operational procedures.
• Long-Term Flow-Based Calculation Now Formally Embedded: The amendments extend flow-based capacity calculation into the long-term timeframe, moving beyond the day-ahead application that has been the operational standard in Core. Market participants using long-term transmission rights in the Core CCR face a changed technical basis for capacity availability assessments.
• Cross-Border Electricity Trading Conditions Affected: Energy traders, power exchanges, and nominated electricity market operators active in Core CCR markets operate under capacity figures derived from the amended methodologies. Changes to the calculation framework alter the volume and distribution of available cross-border capacity offered to the market.
• Coordinated Implementation Required Across Fifteen Member States: The Core CCR covers Austria, Belgium, Croatia, Czech Republic, France, Germany, Hungary, Luxembourg, the Netherlands, Poland, Romania, Slovakia, Slovenia, and two further members. Coordinated implementation across national regulatory authorities and TSOs in this footprint introduces execution complexity with no single-jurisdiction fallback.

Regulatory Delta

- ACER has issued prior decisions on Core CCR capacity calculation methodologies. The extension of flow-based methodology into the long-term timeframe goes beyond the existing day-ahead framework and represents a structural expansion of its scope.

- The two decisions move long-term capacity calculation in Core from a net transfer capacity basis toward flow-based principles, bringing the long-term timeframe into alignment with the day-ahead standard already operational in Core.

- The European Commission's electricity market design reform, finalized under the revised Electricity Regulation in 2024, explicitly supports flow-based capacity calculation as the preferred methodology across EU bidding zone borders. These decisions sit on the trajectory of that legislative mandate.

Materiality Classification

HIGH — ACER binding decisions amending capacity calculation methodologies carry immediate compliance obligations for transmission system operators across fifteen EU member states and alter the technical framework governing cross-border electricity capacity for all Core CCR market participants.

Intelligence Outlook

Monitor ACER and the Core CCR national regulatory authorities for implementation timelines, any TSO compliance plans filed under this rulemaking, and further methodology decisions extending flow-based calculation to additional timeframes or capacity calculation regions.