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.

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. 

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.

Today, ACER publishes a position paper introducing output performance indicators to measure the performance of grid-enhancing technologies in electricity transmission.

Europe’s energy transition is driving rapid growth in electricity demand and renewable generation, putting increasing pressure on transmission networks. While grid expansion remains key, making better use of existing infrastructure through innovative operational practices, digitalisation and grid-enhancing technologies is equally important, as smart solutions of transmission system operators (TSOs) can often deliver additional capacity faster and at a lower cost.

Why are transmission output performance indicators needed?

EU legislation already requires national regulators to monitor the development of smart electricity grids. To ensure smart grid solutions deliver benefits, regulators need ways to assess their real-world performance. 

The June 2025 Copenhagen Infrastructure Forum invited ACER, together with the European Network of Transmission System Operators for Electricity (ENTSO-E) and other stakeholders, to develop a common approach for assessing the performance of smart-grid solutions at transmission level.

In parallel, the Council of European Energy Regulators (CEER) publishes today its report on indicators to measure performance at distribution level.

Assessing transmission smart grid performance

Transmission smart grid infrastructure can be assessed using two types of indicators:

• input, which describe what has been implemented; and
• output, which monitor what has been achieved.

ACER found that few EU countries currently systematically measure how grid-enhancing technologies perform in practice, making it difficult to assess their effectiveness. This ACER paper addresses this gap. It builds a foundation for more consistent and comparable assessments of TSO performance across Europe.

What does ACER recommend?

ACER proposes three output indicators for regulators to assess whether grid-enhancing technologies in transmission grids deliver improvements and cost benefits:

• performance of existing transmission assets in real-time system operations,
• performance of operational security; and
• grid expansion performance.

These performance indicators address grid capacity gains, operational-security cost reductions and cost-efficient alternatives to conventional grid expansion. By capturing their actual performance, these output indicators help ensure that innovative approaches truly unlock grid capacity and reduce system costs. 

Beyond the three proposed output indicators, the paper also highlights complementary areas of monitoring that can enhance regulatory insight.

• ACER recommendation for national regulators: Incorporate the proposed indicators as a common framework for monitoring smart-grid performance at transmission level, allowing a two- to three-year transition period for data collection, process setup and methodological refinement.
• ACER recommendation for transmission system operators: Develop complementary input indicators reflecting the availability of tools that influence the proposed output indicators, with ENTSO-E providing guidance and reference mappings to ensure consistency across the EU.

What are the next steps?

Implementation should follow a phased, learning-oriented approach, starting with national testing of the indicators. A two- to three-year transition period will allow regulators to adjust them where needed as they are further developed and implemented.

Over time, the accumulated data and shared experience can support more systematic assessment of grid performance and innovation across Europe.

ACER published its report on the implementation of the inter-transmission system operators compensation mechanism (ITC) for 2024. 

ACER issues these yearly monitoring reports since 2012, as mandated by the Commission’s Regulation. 

What is the ITC mechanism?

The inter-transmission system operators compensation (ITC) mechanism, managed by the European Network of Transmission System Operators for Electricity (ENTSO-E), compensates transmission system operators (TSOs) for the costs of hosting cross-border flows on their networks (including costs from power losses and infrastructure investments).

The mechanism works through the ITC fund: participating TSOs both contribute and receive money from it, depending on how much electricity they import, export and transmit across their national borders. The aim of the mechanism is to ensure that costs and benefits are fairly shared among the TSOs.

The ITC mechanism currently includes 36 TSOs from across the EU and neighbouring countries, including the Ukrainian TSO Ukrenergo, who officially joined the ITC agreement in July 2024.

What are the key findings for 2024? 

• After increasing significantly in 2022 and 2023, the ITC fund fell from €1.14 billion in 2023 to €879.9 million in 2024, mostly due to a decrease in electricity wholesale prices (although these remain well above pre-crisis levels).
• As a result of lower wholesale prices, most TSOs (28 out of 36) saw lower loss costs compared to 2023. On average, weighted loss costs fell 28% to 145.97 €/MWh.
• As in previous years, the cost of losses varied widely among EU ITC parties, ranging from 63 to 259 €/MWh. Actual electricity losses also differed significantly across countries.
• ACER finds that the ITC mechanism in 2024 generally complies with EU legal requirements. However, it recommends further methodological improvements, in line with its Recommendation on the treatment of losses (2023), including calculating loss volumes in more detail and using actual loss costs.

What are the next steps?

ACER is currently reviewing existing EU mechanisms for sharing the costs and benefits of electricity network infrastructure arising from cross-border trade, including the ITC mechanism. The aim is to better reflect the EU-wide benefits of the grid and to facilitate infrastructure investments that extend beyond national interests and needs. The findings of this exercise will feed into an ACER policy paper in 2026.

Access all ACER ITC monitoring reports.

On 17 December 2025, the European Network of Transmission System Operators for Electricity (ENTSO-E) submitted its proposal for the European Resource Adequacy Assessment (ERAA) 2025 to ACER.

What is ERAA?

Mandated by the 2019 Clean Energy Package, the ERAA is ENTSO-E’s annual evaluation of the risks to the EU’s security of electricity supply for up to 10 years ahead. Following the methodology approved by ACER in 2020, ENTSO-E must carry out an annual assessment on whether the EU has sufficient electricity resources to meet future demand.

At national level, Member States set their own electricity reliability standards to indicate the level of security of electricity supply they need. At European level, the ERAA verifies whether the EU’s electricity system can meet these national standards. 

How does the ERAA benefit the EU?

The ERAA provides an objective basis for identifying potential risks to Europe’s security of electricity supply and for determining whether additional national measures, such as capacity mechanisms, are needed. It helps inform decisions by Member States and the European Commission (e.g. state aid decisions) on national security of electricity supply measures.

What are the next steps?

Every year, where necessary, ACER suggests how to improve the next ERAA before ENTSO-E begins its work (e.g. see ACER suggestions for the ERAA 2025). ACER also actively engages with ENTSO-E throughout the year.

ACER will review and decide on ENTSO-E’s proposed ERAA 2025 within three months of its submission. 

Read more on ERAA.

On 2 July 2025, ACER received a proposal from the EU transmission system operators (TSOs) to amend the methodology for intraday cross-zonal gate opening and closure time. 

What is the methodology about?

Established under the Capacity Allocation and Congestion Management (CACM) Regulation, the methodology sets harmonised rules across EU Member States for when electricity trading can begin (gate opening time) and end (gate closure time) in the intraday market. The intraday market is a short-term market where electricity is bought and sold on the same day as delivery after the day-ahead market has closed. 

The TSOs proposed shortening the gate closure time from the current 60 to 30 minutes before delivery, while keeping the gate opening time unchanged. 

Shortening the gate closure time is expected to:

• allow market participants to trade closer to real time, giving them more time to respond to last-minute changes in demand and supply;
• support the integration of renewable energy sources and flexibility solutions; and
• help TSOs keep the system balanced and the supply secure.

This amendment aims to align the methodology with the requirements of the Electricity Market Design Reform (2024), which seeks to improve the efficiency of short-term markets.

What did ACER decide? 

On 19 December 2025, ACER approved the TSOs proposal, adding several clarifications and adjustments, including:

• Derogations and the 30-minute gate closure time: If a TSO receives a derogation, the 30-minute gate closure time cannot be applied on that bidding-zone border until the derogation ends. The TSO on the opposite side of the border does not need its own derogation; it simply continues applying the 60-minute gate closure time. Once all derogations on that border expire, all involved TSOs must switch to the 30-minute standard without delay.
• Borders with Energy Community Contracting Parties: As the Electricity Market Design Reform has not yet been fully adopted by the Energy Community Ministerial Council, it is not part of national laws in thee Energy Community countries. Until adoption, applying the 30-minute gate closure time on these borders is optional, while the 60-minute remains the mandatory standard.

What are the next steps? 

From 1 January 2026, the first TSOs will start implementing the 30-minutes gate closure time, with full rollout subject to national regulatory decisions.

On 18 December 2025, ACER received two proposals from the European electricity transmission system operators (TSOs) to amend the implementation frameworks for two European platforms for exchanging balancing energy.  

These frameworks describe the design of the Platform for the International Coordination of Automated Frequency Restoration and Stable System Operation (PICASSO) and Manually Activated Reserves Initiative (MARI). These European platforms help integrate European balancing energy markets by using a common merit order list to enable cost-efficient activation of balancing energy bids across Europe.

What are the proposals about?

The TSOs’ proposals amend how balancing service providers (BSPs) participate in the European balancing markets. These markets operate in near real time, with BSPs offering services that TSOs purchase to correct imbalances (e.g. by increasing electricity generation or reducing consumption) and keep the electricity system secure.

The main focus of the TSOs’ proposals is the harmonisation of the BSPs prequalification process, which ensures that power generation or demand units meet the technical and operational requirements to provide balancing services. The proposals also harmonise the procedure for amending the implementation frameworks for the balancing platforms across Europe. 

Why amend the implementation frameworks?

As cross-border exchanges of balancing products grow, ensuring a level playing field for BSPs becomes increasingly important. Harmonising prequalification rules across Member States is key to ensuring fair, transparent and efficient access to European balancing markets.

What are the next steps?

ACER will review the TSOs’ proposals to ensure they align with the Electricity Balancing Regulation and the Regulation on the Internal Market for Electricity. 

To inform its decision, ACER will run a public consultation from 26 January 2026 to 23 February 2026.

ACER will decide whether to amend the implementation frameworks by 18 June 2026.