On 21 July 2026, ACER received a proposal from all nominated electricity market operators (NEMOs) to amend the methodology for the price coupling, continuous trading matching and intraday auction algorithms.

What is the methodology about?

Established under the Capacity Allocation and Congestion Management (CACM) Regulation, the methodology provides a common framework for the algorithms used to simultaneously match electricity market orders and allocate cross-zonal capacities in Europe’s day-ahead and intraday markets. It defines common requirements, timelines and implementation deadlines.

The current methodology was approved by ACER in July 2018 and amended in January 2020 and September 2024.

Why amend the methodology? 

NEMOs propose amendments to the methodology to enable more efficient cross-border electricity exchanges, deliver greater welfare and maintain the secure operation of the power system by:

• enabling the introduction of three intraday auctions using flow-based capacity calculation by updating the timings and delivery of intraday auction results;

• setting a concrete implementation deadline for flow-based allocation in intraday auctions; and

• amending the relevant deadline for publishing the single day-ahead coupling results.

What are the next steps? 

ACER expects to decide on the methodology by 21 January 2027. 

Interested stakeholders are invited to share their views on the topic by 31 August 2026 via ACER-ELE-2026-006@acer.europa.eu.

ACER’s new retail energy markets dashboard offers an interactive, country-by-country view of electricity and gas markets across the EU and Norway. It replaces ACER’s country sheets, bringing together comparable data to explore how retail markets are evolving and how consumers’ behaviour changes alongside the energy transition.

What trends did ACER monitoring find?

With over 270 million electricity and more than 90 million gas customers across the EU and Norway, retail energy markets play an important role in supporting Europe’s energy transition. At the same time, the latest data shows ongoing challenges and significant untapped potential for more active consumer participation.

• Energy bills remain above pre-crisis levels. Retail prices rose sharply after the 2021-2022 energy crisis and remained elevated, with gas prices still nearly 70% higher than before the crisis. On average, EU households spent around €840 on electricity and €1,170 on gas in 2025.
• Household electricity and gas consumption is rising modestly, highlighting the importance of enabling consumers to actively manage their energy use.
• Fixed contracts remain the most common contract type. Around 52% of household electricity customers are on single fixed-price, fixed-term contracts, while only 7% are on dynamic-price contracts, pointing to significant unexploited capacity for demand-side flexibility.
• Smart meter rollout progresses unevenly. 66% of household customers monitored across the EU and Norway have a smart meter. While deployment exceeds 80% in most EU Member States, it remains below 20% in several countries, limiting consumers’ ability to adjust their consumption in real time.

What are the next steps?

The retail energy markets dashboard will be updated annually as new data becomes available, allowing to monitor progress across all indicators.

On 17 July 2026, the national regulatory authorities of the Core capacity calculation region (Core NRAs) asked ACER for a three-month extension to decide on the proposal to amend the Core intraday capacity calculation methodology. The proposal was submitted by the transmission system operators of the Core region (Core TSOs).

The Core region is the EU’s largest electricity capacity calculation region, covering 13 Member States: Austria, Belgium, Croatia, Czech Republic, France, Germany, Hungary, Luxembourg, the Netherlands, Poland, Romania, Slovakia and Slovenia.

ACER intends to ensure a timely decision on the matter.

What is the Core intraday capacity calculation methodology? 

The methodology determines how much cross-zonal transmission capacity is available for intraday electricity trading in the Core region. 

First approved in 2020, the methodology would now be amended for the sixth time to reflect the continued development of capacity calculation and support EU electricity market integration through more efficient and secure allocation of cross-zonal capacity.

On 7 July 2026, the national regulatory authorities of the Continental Europe Synchronous Area asked ACER to decide on the minimum activation period that frequency containment reserves providers with limited energy reservoirs must ensure to remain available during the alert state.

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

Why is the minimum activation period important?

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 reserves are the first line of automatic response to such deviations. They are activated within seconds to stabilise the frequency and are 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. 

What are the next steps? 

ACER intends to decide on the minimum activation period within 6 months. 

ACER has adopted two decisions amending the day-ahead and long-term capacity calculation methodologies for the Core capacity calculation region (CCR).

The Core CCR is the EU’s largest electricity capacity calculation region, covering 13 Member States: Austria, Belgium, Croatia, Czech Republic, France, Germany, Hungary, Luxembourg, the Netherlands, Poland, Romania, Slovakia and Slovenia.

ACER Decisions follow referrals by the regional national regulatory authorities under the Capacity Calculation and Congestion Management and the Forward Capacity Allocation Regulations.

What are the methodologies about?

Capacity calculation methodologies determine how much cross-border transmission capacity can be made available to electricity markets.

The day-ahead methodology determines how much electricity capacity is available for cross-border trading one day before delivery. The long-term methodology covers yearly and monthly capacity calculations, enabling long-term planning and hedging opportunities.

In the Core region, both methodologies apply a flow-based approach, meaning capacities are calculated by accounting for actual transmission network constraints. This improves efficiency compared to simpler methods.

Why amend them?

Currently, long-term capacity allocations are included in the day-ahead capacity calculation process. The Core transmission system operators (TSOs) proposed separating these two timeframes so that operational security, which is central to day-ahead capacity calculation, is no longer linked to the volume of capacity allocated in the long-term timeframe. 

This separation aims to better harmonise the region’s market timeframes and facilitate the transition towards long-term flow-based capacity calculation, planned for 2027.

What did ACER decide?

After reviewing the TSOs’ proposals and consulting with stakeholders, ACER approved the amendments, introducing changes to strengthen legal clarity and ensure compliance with EU electricity market rules.

Key amendments include:

Long-term methodology:

• introducing benchmark available transfer capacity (ATC) values as a transitional measure to support flow-based capacity calculation, better reflecting historical cross-border transmission capacities;
• establishing formal amendment procedures for any future changes to these values; and
• integrating the Ireland and Northern Ireland single electricity market–France bidding zone border into the Core region, following the commissioning of the Celtic Interconnector.

Day-ahead methodology:

• removing long-term allocations from the capacity calculation process; and
• updating the methodology to reflect the transmission system’s expansion and new infrastructure (including the Celtic Interconnector).

ACER’s Decisions support consistent capacity calculation in the Core region and facilitate the implementation of long-term flow-based capacity calculation.

Next steps

The Core TSOs must implement both amended methodologies for the 2027 capacity calculation processes.

Today, ACER published its Opinion on Romania’s National Resource Adequacy Assessment (NRAA), which complements the European Resource Adequacy Assessment (ERAA) 2025 edition.

What is a resource adequacy assessment?

The ERAA evaluates electricity resource adequacy across the EU and provides a consistent framework to assess whether additional national measures may be needed to ensure security of supply. It is carried out annually by the European Network of Transmission System Operators for Electricity (ENTSO-E) and reviewed by ACER.

Member States can complement the European analysis through national assessments (NRAAs) to reflect local conditions. When a national assessment identifies different adequacy concerns from the European assessment, ACER issues an opinion.

What did the Romanian NRAA find?

Romania’s NRAA identifies resource adequacy concerns for both 2027 and 2035 under its central reference scenario, indicating a higher risk of electricity supply shortages than the ERAA 2025 edition.

The assessment points to a slower-than-expected energy transition, driven by delays in renewable energy deployment and in the commissioning of new thermal generation capacity, along with a conservative rollout of non-fossil flexibility resources. As a result, the assessment finds that Romania’s electricity system may face resource shortages, potentially affecting the planned phase-out of coal-fired generation.

What does ACER recommend?

ACER acknowledges the rationale for adjusting capacity projections, originally based on the National Energy and Climate Plans, to better reflect recent market developments. However, long-term assumptions on generation capacity (for 2030 and 2035) should remain consistent with the projected pace of electrification.

To reinforce the assessment and provide a more robust evaluation of Romania’s resource adequacy risks, ACER recommends:

• Using the latest information on thermal generation projects. Coal phase-out assumptions should reflect current delays in the commissioning of new gas-fired power plants and the slower deployment of renewable energy. This is particularly important in the short term, as the electricity system still relies on thermal generation.
• Better reflecting the growing role of non-fossil flexibility. The assessment should capture the continued expansion of battery storage and demand response, including flexibility from data centres, across all target years up to 2035. These resources are expected to play an increasingly important role in maintaining security of supply during Romania’s energy transition, supported by emerging national policies, such as draft regulations on demand-side flexibility and the removal of double charging for electricity storage.
• Assessing the economic viability of new investments. The assessment should consider whether projected investments in flexible resources, such as demand response and storage, are commercially viable and therefore likely to be delivered. This would ensure that future flexibility needs can be met at the anticipated pace of electrification and renewables deployment.

Example: Historical and projected installed wind capacity

The Romanian assessment reflects a slower energy transition than the ERAA, with lower projected wind capacity in the first target year in line with recent trends, while still assuming continued growth toward national renewable energy targets.

Source: ACER based on Transparency Platform, Summer Outlook, the NRAA and ERAA 2025.

What are the next steps?

ACER encourages the Romanian authorities to:

• Consider its feedback to improve the assessment of the country’s resource adequacy risks.
• Regularly submit updated projections for realistic resource capacity and electricity demand in future ERAAs, ensuring they reflect latest market developments. This will support more realistic planning at EU level and align with the updated ERAA methodology, which includes a new ‘Trends and Projections’ scenario to capture potential deviations from National Energy and Climate Plans trajectories.

ACER publishes today its Opinion on the draft TYNDP 2026 Scenarios Report prepared by the European Network of Transmission System Operators for Electricity and Gas (ENTSO-E and ENTSOG) under the TEN-E Regulation. 

These scenarios, produced every two years, provide the common foundation for EU-wide electricity, gas and hydrogen infrastructure planning, and feed into the Ten-Year Network Development Plans (TYNDPs).

ACER’s Opinion assesses whether the ENTSOs’ scenarios comply with ACER’s Framework Guidelines and provide a transparent and consistent basis for infrastructure planning.

What are the key findings?

ACER welcomes the significant work by ENTSO-E and ENTSOG to improve the scenarios’ accuracy, including:

• the continued delivery of joint scenarios combining electricity, gas and hydrogen; 
• the introduction of economic variants (high- and low-growth cases applied to the central scenario to assess the robustness of the underlying economic assumptions);
• the involvement of the Stakeholder Reference Group, which gives stakeholders structured scrutiny over the scenarios’ assumptions, methods and data; and
• the development of an Innovation Roadmap, which sets out planned improvements to the scenario-modelling tools and methods, and is updated every two years.

ACER also identifies two main areas for improvement:

• Alignment with EU climate and energy targets. The current methodology enables formal compliance with EU targets, but ACER considers that it does not adequately capture the structural changes needed to achieve those targets in practice.
• Stronger economic variants. These should function as meaningful alternative scenarios, with greater transparency and consultation on key scenario assumptions and infrastructure planning inputs, improved consistency with the European Resource Adequacy Assessment (ERAA) and a more timely scenario development process.

What are the next steps?

For the finalisation of the TYNDP 2026 Scenarios Report, ACER calls on ENTSOs to improve transparency on the remaining gap to EU climate and energy targets and the limitations of the current methodology.

For future cycles, ACER expects further improvements in EU targets alignment, economic variants, consistency with ERAA, stakeholder consultation and the overall timeliness of the process.

The European Commission will take ACER’s Opinion into account when assessing the draft TYNDP 2026 Scenarios Report.

In March 2026, ACER received a proposal from the European Network of Transmission System Operators for Electricity (ENTSO-E) to amend the methodology for the regional sizing of reserve capacity. After reviewing the proposal and exchanging with stakeholders, ACER has decided to amend the methodology.

What is the methodology about?

The methodology for the regional sizing of reserve capacity (first approved by ACER in 2023) allows regional coordination centres (RCCs) to assess the reserves needed at regional level, taking into account volumes shared between transmission system operators (TSOs) through bilateral agreements. 

This coordination helps reduce procurement costs and ensure a more efficient distribution of reserves across Europe. Based on their assessment, RCCs provide TSOs with recommendations on how to optimise reserve capacity volumes, leveraging the flexibility of the EU electricity system.

What’s new in the amended methodology?

As previously requested by ACER, the methodology now:

• Establishes that all RCCs must rely on data from the previous 12 months when assessing the minimum volume of reserves needed for the following year. This ensures the data used reflects the most relevant and frequent system conditions.
• Specifies, for each system operation region, how much reserve capacity is needed to cover positive and negative imbalances. 
• Introduces a 24-month rolling implementation deadline for assessing the short-term availability of reserve capacity (for sharing agreements established after 1 July 2026).
• Enhances transparency by strengthening and streamlining RCCs’ reporting obligations.

These changes will help RCCs size reserve capacity more efficiently, address TSOs’ operational risks and enhance the process’ transparency and coordination.

What are the next steps? 

As previously agreed, RCCs must implement the methodology’s main changes by 1 July 2026.

On 10 June 2026, transmission system operators (TSOs) submitted a proposal to ACER to revise the harmonised allocation rules (HAR) and the requirements for the single allocation platform (SAP).

To inform its decision-making process, ACER will open a public consultation on 10 July 2026.

What are these rules about?

The harmonised allocation rules apply to all allocations of long-term transmission rights performed in the European Union. They provide specifications for the auctioning of long-term transmission rights (including their use, curtailment and eligibility criteria) and go through a review process every two years. All TSOs issuing long-term transmission rights are required to offer long-term cross-zonal capacity to market participants through the single allocation platform.

Why amend them?

With the implementation of long-term flow-based allocation, long-term transmission rights for all bidding zone borders within a capacity calculation region will be allocated with a single auction. 

Currently, collaterals (i.e. financial security provided by market participants to guarantee their payment obligations) for long-term transmission rights are reserved until the auction is cleared, often leading to an overestimation of collaterals’ needs. As long-term flow-based allocation combines multiple bidding zone borders, this over-reservation further increases collateral requirements for market participants. This, in turn, may result in unnecessary bid rejections by market participants and potential welfare losses.

To address this, TSOs propose to amend the harmonised allocation rules and the single allocation platform's requirements by introducing a new collateral management solution.

What are the next steps?

The public consultation runs from 10 July until 7 August 2026. Access the survey.

ACER will analyse the feedback received and reach a decision by 10 December 2026.

ACER has launched the first edition of its electricity network tariff repository. 

Why network tariffs matter

Network tariffs are a key part of electricity bills, used to recover the costs of investing in, maintaining and operating electricity networks. As Europe’s power system evolves, the grid needs to support more electrification, more renewable energy and new patterns of grid use. Based on sector estimates, investments in electricity networks could reach up to €2,600 billion by 2050 to integrate the rise of renewable energy (see ACER’s 2024 infrastructure report). With the ramp-up of grid investments, network costs are a big driver of overall electricity costs.

Clear and comparable tariff information is therefore important for understanding how network costs are allocated, how tariff structures differ across countries and how tariff design may support efficient use of the grid. This supports broader EU efforts to improve energy affordability and ensure electricity grids are fit for the future, including the European Commission’s upcoming network charges plan, which is part of its energy package expected on 10 June. 

Network tariff repository 

This new ACER repository brings together tariff information from EU Member States in one centralised platform. It complements national transparency efforts and supports access to electricity network tariff data at European level.

The dashboard aims to improve comparability and understanding of national approaches to network cost recovery and tariff setting.

Who can use ACER’s network tariff repository?

Whether for analysis, benchmarking or strategy the repository offers easy access to electricity network tariff information from across Europe to national regulatory authorities, policymakers, network operators, researchers, analysts, and consumer and industry organisations. 

Use case 1 – Electricity bills: An analyst comparing electricity bills across Europe could use the repository to check whether network charges are mainly fixed, capacity-based or energy consumption-based in different Member States and therefore understand the underlying cost drivers. 

Use case 2 – National tariff methodologies: A regulator reviewing its national tariff methodology could compare how other Member States structure and allocate network charges for households and businesses.

What’s next?

The repository will be progressively updated with data and additional information, including tariff practices and relevant studies underlying key network tariffication choices. 

The dashboard will also provide input for ACER’s future analytical work, including the next edition of ACER’s report on electricity network tariff practices, expected in 2027. 

Disclaimer: This electricity network tariff repository is published as a work-in-progress tool. The repository is intended to improve access to tariff-related information and will support ACER’s future analytical work.

Check ACER's new dashboard.