On 27 February 2026, ACER will open a public consultation on economic input data to improve electricity system modelling across Europe. The aim of this consultation is to ensure that the inputs used in European-level modelling are robust, transparent and properly grounded in national market realities.

Why are we consulting?

Realistic cost assumptions are key for effective long-term electricity system modelling, including the one used by ENTSO-E for the European Resource Adequacy Assessment (ERAA). These models are used to assess future investment needs, such as whether new power generation or flexibility resources are likely to be built, and whether existing power plants are expected to remain economically viable.

ACER has recently commissioned a consultancy study on investment parameters. As part of it, the consultant delivered a comprehensive EU-wide economic dataset for electricity system modelling. This new dataset shows estimated investments and operational costs for different power generation technologies and demand-side flexibility at Member State level.

Get involved!

Stakeholders are encouraged to review the data for their relevant Member State(s), assess whether it reflects current market and technological developments and propose evidence-based alternatives. 

The consultation will run from 27 February 2026 until 27 March 2026.

What’s next?

These figures will help shape how Europe’s power system develops in the years ahead.

ACER will examine the feedback received and revise the dataset to ensure accuracy and credibility. The finalised data will then be used to improve future ERAA modelling by ENTSO-E, as well as to help Member States in the procedure of fast-track approval of capacity mechanisms under the new State aid framework.

ACER will consult on amendments to the long-term capacity calculation methodology of the Core capacity calculation region (CCR) from 27 February until 27 March 2026.

On 21 November 2025, the Core CCR’s transmission system operators (TSOs) submitted a proposal to their national regulatory authorities (NRAs) to amend the long-term capacity calculation methodology. As the NRAs could not reach an agreement, the proposal was referred to ACER on 4 February 2026 under the Forward Capacity Allocation Regulation. 

The Core CCR comprises 13 countries: Austria, Belgium, Czech Republic, Croatia, France, Germany, Hungary, Luxembourg, the Netherlands, Poland, Romania, Slovakia and Slovenia.

What is the methodology about?

Long‐term cross-border capacity calculation promotes efficient long‐term cross‐zonal trade. By providing reliable capacities to market participants early, it enables long-term planning and hedging opportunities.

The Core CCR’s long-term methodology covers both yearly and monthly processes, using the flow-based approach.

Why change it?

In their proposal, TSOs recommend to:

• Introduce a benchmark process for available transfer capacity, adjusting the flow-based capacity calculation to better reflect historical cross-border transmission capacities.
• Integrate the Ireland and Northern Ireland single electricity market - France bidding zone border into the Core CCR’s long-term capacity calculation process, once the Celtic interconnector is commissioned.

The proposed changes aim to improve long-term capacity calculation in the Core CCR by enabling the implementation of the flow-based methodology. As a transitional measure, the benchmark for available transfer capacity would be applied at the end of the process. This would allow the yearly auction at the end of 2026 (for delivery in 2027), as well as the monthly auctions in 2027, to take place.

The inclusion of the Ireland and Northern Ireland single electricity market – France bidding zone border reflects its recent integration into the Core CCR. 

What are the next steps?

ACER aims to reach a decision by 4 August 2026. The Core TSOs shall implement the long-term capacity calculation methodology by the end of 2026.

On 11 February 2026, ACER issued its Opinion on the Winter Supply Outlook 2025/2026, published by the European Network of Transmission System Operators for Gas (ENTSOG). 

What’s in ENTSOG’s Outlook?

This year’s Outlook is particularly timely in light of the recent EU measure phasing out Russian gas imports. Against this backdrop, ENTSOG’s Outlook evaluates the gas system readiness for winter 2025/2026, considering a gradual phase-out of Russian gas. 

• EU entered winter with lower gas storage (83%) than last year (94%), but still has sufficient gas to meet demand.
• Storage levels are expected to remain above 30% by the end of winter, even if remaining Russian flows via TurkStream are fully disrupted.
• LNG availability is the main supply risk, as LNG now covers around 40% of EU gas demand.
• In a low-LNG scenario, gas storage could be depleted by the end of winter, potentially requiring demand reduction measures.

What does ACER say?

ACER welcomes ENTSOG’s extensive testing of the gas system, including cold winter scenarios, supply disruptions and updated infrastructure data. It also recognises the clear inclusion of the Russian gas phase-out in the Outlook, as well as consideration of the remaining gas dependency in the electricity sector, as highlighted in ACER’s security of supply Monitoring Report (November 2025).

However, ACER notes that a more holistic assessment of security of supply requires shifting the focus from infrastructure (which is currently not the main bottleneck) towards supply challenges and diversification. 

What does ACER recommend?

ACER recommends that ENTSOG, in its future outlooks, adjust its analysis to better reflect supply risks and market dynamics by:

• Shifting the analysis towards gas supply availability and LNG market dynamics, rather than infrastructure resilience.
• Assessing LNG supply based on EU regasification capacity and destination-free global LNG volumes, as reflected in the high-LNG scenario, rather than capping LNG supply in the reference and low-LNG scenarios only based on historic averages.

The European Commission is inviting applications to appoint new members and alternates of ACER’s Board of Appeal. Successful candidates will serve on the Board for its next mandate, starting on 18 October 2026.

Applications are open until 31 March 2026 (midnight Brussels time).

See the call for interest for details and instructions on how to apply.

About the Board of Appeal

ACER’s Board of Appeal operates as an independent body to address complaints lodged against ACER decisions. It is part of ACER but at the same time independent from its administrative and regulatory structure. As such, its members and alternates act independently and in the public interest. 

The Board is composed by six members and six alternates serving for a 5-year mandate (renewable once). Members and alternates are selected among current or former senior staff of the national regulatory authorities (NRAs), competition authorities or other national or EU institutions with relevant experience in the energy sector.​

In August 2025, ACER has received a proposal from Nominated Electricity Market Operators (NEMOs) to amend the harmonised maximum and minimum clearing price (HMMCP) methodologies for the EU day-ahead and intraday market coupling.

On 4 February 2026, ACER has approved NEMOs’ proposal.

Why is market coupling important?

Before market coupling was introduced in the EU, electricity and cross-zonal transmission grid capacity had to be purchased separately. Today, market coupling (of day-ahead and intraday markets) allocates scarce cross-zonal transmission grid capacity efficiently by coupling wholesale electricity markets across the EU, while taking into account physical grid constraints.

What are the methodologies about?

The HMMCP methodologies (first approved by ACER in 2017 and amended in 2023) set the maximum and minimum price limits in the EU single day-ahead and intraday electricity markets. 

Established under the Capacity Allocation and Congestion Management (CACM) Regulation, the methodologies also define the harmonised automatic price adjustment mechanism and specify how it is triggered when the applicable price limits are reached in the day-ahead and intraday markets. 

Why amend the methodologies and what’s new?

ACER amended the methodologies to clarify how the automatic price adjustment mechanism applies in rare market conditions.

In case of partial decoupling within a bidding zone where multiple NEMOs operate but not all are decoupled, the bidding zone will remain in market coupling, potentially with low liquidity. The amended methodologies clarify that, in such cases, the harmonised automatic price adjustment mechanism cannot be triggered. 

What are the next steps? 

Following this ACER Decision, NEMOs are required to promptly implement the amendments. 

On 3 December 2025, the national regulatory authorities (NRAs) of the Continental Europe Synchronous Area submitted to ACER a joint request for a six-month extension to decide on the transmission system operators’ (TSOs’) proposal. This concerned the minimum activation period that frequency containment reserve providers with limited energy reservoirs must ensure in order to remain available during the alert state.

On 30 January 2026, with its Decision 01/2026, ACER granted the extension requested by the NRAs, who now have until 17 June 2026 to reach an agreement on the TSOs’ proposal. 

The countries of Continental Europe Synchronous Area are Austria, Belgium, Bulgaria, Croatia, Czechia, Denmark, Estonia, France, Germany, Greece, Hungary, Italy, Latvia, Lithuania, Luxembourg, the Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia and Spain.

What is it about?

EU’s electric power systems operate at the frequency of 50 Hz. Any imbalance between electricity supply and demand causes the frequency to deviate. If not corrected quickly, this can lead to blackouts.

Frequency containment reserve is the first line of automatic response to such deviations. It is activated within seconds to stabilise the frequency and is provided continuously by power-generating or consuming assets (like batteries, hydro plants or demand response systems). 

Some of these providers, especially batteries or demand-side resources, have limited energy reservoirs and can only respond for a short duration. The System Operation Regulation therefore requires a minimum activation time to ensure these resources remain available during the alert state. 

ACER has published its Rules of Procedure setting out how it will conduct cross-border investigations into suspected energy market abuse. 

Why do the new rules for cross-border probes matter?

Europe has an EU-wide framework (called REMIT) to detect and deter abuse in wholesale energy markets. Breaches of REMIT are enforced at national level by energy regulators. However, market manipulation and abuse often transcend national borders and cases can be sophisticated.

In 2024, EU legislators updated the REMIT framework giving ACER additional tasks, including the mandate to investigate cross-border cases.

ACER’s expanded role helps build a stronger regulatory framework, promoting openness and confidence in EU energy markets, and strengthens trust that wholesale energy prices are transparent and fair. 

What is the scope of ACER’s cross-border investigatory mandate?

ACER can investigate REMIT cases that affect two or more countries, including breaches of:

• prohibitions on insider trading and market manipulation;
• obligations to disclose inside information and to report data; and
• obligations on persons professionally arranging and executing transactions (PPAETs).

When investigating cases with a cross-border dimension, ACER may carry out searches of premises, request information, ask questions of individuals and take statements. 

REMIT enforcement remains the responsibility of national regulatory authorities (NRAs), not ACER.

ACER’s Rules of Procedure for REMIT investigations

ACER’s new Rules of Procedure establish the procedural framework within which ACER carries out its investigatory tasks under REMIT. Their publication ensures legal certainty, due process, fairness and efficiency. The rules set out the main stages of ACER’s investigations, the related decision-making and the rights and obligations of the persons concerned. 

These rules mark an important milestone. As ACER and NRAs continue to work closely together, they will play a key role in ensuring robust, consistent and legally sound enforcement across borders.

What’s next? 

• ACER moves into action on cross-border investigations from the second half of 2026.
• The annual REMIT workshop, organised jointly by ACER and the European Commission, will take place in the summer.
• ACER’s upcoming public consultation on REMIT transaction reporting will gather input from market participants to help shape practical guidance under the revised REMIT framework.
• New guidance on data reporting and updated LNG market data practices will be introduced, following the adoption of REMIT secondary legislation.
• Stakeholders will continue to receive updates and support through online resources.

Have you noticed a potential breach of REMIT rules?

Report it through our notification platform.

Today, ACER publishes its Opinion on the Integrated Model report for EU electricity, gas and hydrogen infrastructure planning, submitted in October 2025 by the European Network of Transmission System Operators for Electricity (ENTSO-E) and for Gas (ENTSOG) and prepared with support from the European Network of Network Operators for Hydrogen (ENNOH).

The Trans-European Energy Infrastructure (TEN-E) Regulation requires ENTSO-E and ENTSOG to jointly develop a consistent and progressively integrated model to support coordinated infrastructure planning across the three sectors (electricity, gas and hydrogen), and underpin future EU-level Ten-Year Network Development Plans (TYNDPs).

Why is an integrated modelling framework needed for EU energy infrastructure planning?

Europe’s energy transition is increasingly blurring the boundaries between electricity, gas and hydrogen systems. Decisions in one sector directly affect infrastructure needs and costs in the others. To address this, EU law requires a shift from isolated, single-sector planning towards more coherent sectoral integration of the modelling governance, processes, tools and data used in electricity, gas and hydrogen network planning.

Such an integrated modelling framework aims to ensure that EU infrastructure plans are based on consistent assumptions, aligned methodologies and comparable cross-sector assessments. It should future-proof planning and inform project-level investment decisions from a system-wide perspective.

What does ACER say about the proposed integrated modelling framework for energy infrastructure planning?

ACER’s Opinion assesses whether the ENTSOs’ submission provides a sufficiently robust basis for more coherent, cross-sector infrastructure planning at EU level.

The report is a useful starting point, with some progress beyond joint scenario development, including the creation of a dedicated cross-sector working group with balanced representation across the three sectors.

However, ACER finds the report does not clarify how the integrated modelling framework will contribute to greater consistency and integration of EU infrastructure planning through concrete milestones. The report falls short in the following areas:

• Cross-sector integration requirements are unclear, leaving implementation discretionary.
• Key integration steps are deferred to a long-term roadmap with vague timelines and under-ambitious actions.
• Stakeholder consultation was limited, with key elements excluded (draft report and roadmap).

As a result, it remains unclear whether the proposed framework will deliver practical improvements in infrastructure needs assessments, investment decision-making or system-wide cost optimisation.

What does ACER recommend?

For better EU infrastructure planning, ACER calls on ENTSO-E and ENTSOG, together with ENNOH, to be more ambitious in their approach to integrated modelling:

• Clearly define assumptions, data and methodologies to be applied consistently across sectors.
• Identify which planning steps require joint cross-sector assessment and which can remain sector-specific.
• Apply shared reference networks and indicators in project-level cost-benefit analyses (CBAs).
• Strengthen consistency in identifying infrastructure gaps.
• Ensure cross-sector needs assessments and harmonised CBA pilots are conducted within the TYNDP 2028 cycle.
• Update the roadmap with more ambitious actions and firmer timelines.
• Conduct a more thorough public consultation on the revised model and roadmap.

ACER expects that consistency in input, assumptions and methodology is already applied in TYNDP 2028, even if some deliverables remain sector-specific.

What are the next steps?

ACER expects ENTSO-E and ENTSOG to implement these recommendations before submitting the report to the European Commission for approval. ACER calls for early and meaningful stakeholder engagement as the integrated modelling framework evolves.

ACER issues today its guidance on the information to be voluntarily submitted for the monitoring of operational reliability performance indicators related to cybersecurity in the electricity sector, under the Cybersecurity Network Code. 

Who is this guidance for?

This guidance is addressed to stakeholders in the electricity sector, including transmission and distribution system operators (TSOs and DSOs), generators, organised markets, nominated electricity market operators (NEMOs) and balancing responsible parties, as well as providers of critical information and communication technology (ICT) services and managed security services.

Why does it matter?

The operational reliability performance indicators for cybersecurity will measure how effectively electricity sector companies protect their digital systems and mitigate cybersecurity risks to cross-border electricity flows. They will track statistical data on high and critical-impact cyber-attacks, reportable cyber-threats and exploited unpatched vulnerabilities.

By submitting the requested data, stakeholders will allow ACER to monitor trends and assess how cybersecurity performance evolves across the EU electricity sector. 

What information is ACER requesting?

ACER is requesting the following statistical information, as defined by the operational reliability performance indicators listed in the guidance:

• annual number of reportable cyber threats;
• annual number of reportable cyber-attacks; and
• annual number of exploited unpatched (zero day) vulnerabilities.

What’s the timeline to submit the information?

Starting in 2027, ACER will open a submission window once every three years. In the first submission window in 2027, ACER will request data for 2026. From 2030 onwards, each submission will cover the three preceding years.

Unless communicated otherwise, the submission window will be open each reporting year from 15 January to 1 March. 

How will the information be submitted?

To facilitate data collection, ACER will provide access to a secure online tool. More detailed instructions will be made available prior to the first submission window.

What are the next steps? 

Looking ahead, ACER will use this collected data (after careful aggregation to protect sensitive information) as an input to its triannual reporting, supporting EU-level monitoring and informing future efforts to strengthen the EU cyber resilience.