Under the EU’s Regulation on forward capacity allocation (FCA), the Baltic national regulatory authorities were required to decide on the capacity calculation methodology for long-term timeframes by 22 March 2025. This followed a proposal from electricity transmission system operators, submitted on 22 January 2025.

On 20 March 2025, the Baltic regulators (Estonia, Finland, Latvia, Lithuania, Poland and Sweden) requested from ACER a three-month extension to decide on the matter.

In their request, the regulators explained more time is needed to: 

• assess the methodology’s compatibility with existing day-ahead and intraday capacity calculation methods;
• evaluate the technical constraints of the proposed allocation; and
• consider potential updates from Poland's electricity balancing market reform.

What is long-term capacity calculation?

Capacity calculation determines how much electricity can be safely and efficiently exchanged across borders in a given capacity calculation region. It ensures that available transmission capacity is calculated in a consistent and transparent way, supporting reliable cross-border electricity trading in both short- and long-term markets.

Long-term capacity calculation focuses on ensuring that there is enough capacity in the power grid to meet future demand over extended periods (months or even years). This supports the EU’s internal energy market by enabling forward electricity trading and allowing market participants to plan ahead and manage price risks.

What are the next steps? 

ACER plans to act promptly on this request, aiming to reach a decision in June 2025.

On 28 April 2025, a large-scale blackout occurred in Spain and Portugal shortly after 12.30 CEST. There was widespread interruption in power supply in the Iberian Peninsula. Some areas in France close to the border were also affected, albeit for a very short period.

Electricity supply in the affected area has been restored, with the help of power generation resources (such as hydro-power plants) and power interconnections with France and Morocco.

Expert Panel to investigate

An expert panel is being set up by ENTSO-E to investigate the incident. This panel includes transmission system operators, regional coordination centres, ENTSO-E. The relevant national regulatory authorities and ACER are also invited to participate. 

The panel will collect the data and first prepare a factual report, followed by the final report that will analyse the causes of the incident and include recommendations to make the system more resilient.  

ACER stands ready to participate in ENTSO-E’s expert panel and to assist in identifying the root causes of this incident, including possible implications to draw going forward.

Background

Large-scale blackouts are rare in Europe, although they have occurred before:

• 8 January 2021: A disturbance split the European grid into two parts, causing frequency deviations and temporary outages across several countries. The re-synchronization of the two regions incident was resolved within an hour.
• 4 November 2006: Imperfect cross-border coordination on a planned transmission line outage led to a cascading grid failure resulting in a system split and outages across continental Europe.

• 28 September 2003: A power line touching a tree led to other lines overheating, leading to a series of grid failures and a blackout affecting more than 50 million consumers in Italy and Switzerland.

The lessons learned from these incidents led to improvements in cross-border coordination, system operation, and market integration.

In April 2025, the European Network of Transmission System Operators for Electricity (ENTSO-E) submitted its proposal for the European Resource Adequacy Assessment (ERAA) 2024 to ACER.

What is ERAA?

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

At the national level, Member States set their own electricity reliability standards, which indicate the level of security of supply they require. At the European level, ERAA assesses whether the results align with the standards set by the Member States.

How does ERAA benefit the EU?

ERAA provides an objective basis for identifying potential risks to the security of electricity supply in Europe, and whether additional national measures, such as capacity mechanisms, are needed.

What is ACER’s role?

Each year, ACER reviews ENTSO-E’s proposal for ERAA, taking into account the relevant scenarios, assumptions, and results. If approved by ACER, the assessment informs national decisions on the security of electricity supply.

Following ENTSO-E's submission, ACER is conducting its review of the draft ERAA 2024 and will issue its decision in July 2025.

Amendment of future ERAA methodology 

In March 2025, ACER was mandated by the European Commission to amend and streamline the methodology for ERAA. This stems from the Electricity Market Design Reform (July 2024) and the European Commission’s report (March 2025), both calling for streamlined and simplified application of capacity mechanisms.

To initiate the process, ACER requested ENTSO-E to propose amendments to the ERAA methodology by mid-October 2025. ACER will then approve or amend the proposal within 3 months of receipt. 

Read more on ERAA.

ACER issues today its guidelines to better protect cybersecurity information exchanged under the EU-wide network code on sector-specific rules for cybersecurity aspects of cross-border electricity flows (NCCS).

These guidelines are issued for the electricity sector, including transmission and distribution system operators, generators, organised markets, nominated electricity market operators (NEMOs) and the balancing responsible parties, as well as for providers of critical information and communication technology (ICT) services and managed security services.

ACER consulted the EU cybersecurity agency (ENISA), the European Network of Transmission System Operators for Electricity (ENTSO-E), EU DSO Entity and the competent authorities under the electricity cybersecurity network code in preparing these guidelines.

Why are these guidelines important?

Entities from the electricity sector (e.g. network companies and others) are required under the binding electricity-specific cybersecurity network code to share information, including on cyberattacks, threats, risk assessments and cybersecurity expenditures. Preserving the confidentiality of such sensitive information when sharing it among themselves and with relevant authorities is important. 

What are ACER's recommendations?

The guidelines suggest:

• Usage of the Traffic Light Protocol (TLP) to exchange information. The guidelines also provide basic instructions for the electricity sector on how to apply it. In case there are no legally binding national classification schemes applicable to the shared information, the TLP can also be used to share information within a Member State.
• Several methods for anonymising and aggregating information. The guidelines also provide examples of how specific information exchanged under the NCCS could be anonymised or aggregated.

Find out more on the NCCS.

ACER has published its opinion on the amended balancing monitoring plan of the European Network of Transmission System Operators for Electricity (ENTSO-E), suggesting more flexible reporting timelines, while stressing the need for improved data quality. 

How balancing works and why it needs oversight

In balancing markets, balancing energy is used to always keep the power system stable by correcting differences between electricity production and consumption. If there is not enough electricity in the system, transmission system operators (TSOs) procure upward balancing energy. If there is too much electricity, TSOs procure downward balancing energy. In most EU countries, this is done via EU platforms for the activation of balancing energy.  

Under the Electricity Balancing Regulation, ENTSO-E is tasked with overseeing the implementation and integration of balancing mechanisms across the EU. This includes coordinating the use of key platforms for the exchange of balancing energy and providing detailed reports to ACER on progress, efficiency and market integration.

However, delays in some TSOs joining key balancing platforms could hinder the timely publication of monitoring reports, as insufficient operational data may be available for analysis. As a result, ACER has suggested more flexible reporting timelines, while stressing the importance of high-quality balancing data. 

What are ACER’s key messages? 

ACER recommends that ENTSO-E:

• Adopts alternative reporting timelines suggested by ACER.
• Prioritises the quality of balancing data published on the ENTSO-E Transparency Platform to ensure that national regulators and ACER can effectively conduct their respective monitoring and analyses. 
• Streamlines reporting and promptly notifies ACER of any overlaps between reporting obligations, without the need to resubmit the amended Monitoring Plan. 

What are the next steps?

ENTSO-E is encouraged to begin improving data quality without delay.

Looking ahead, ACER commits to working closely with ENTSO-E to progressively reduce the number of reports required, aiming for more efficient and focused monitoring processes. 

The EU Agency for the Cooperation of Energy Regulators (ACER) has submitted its response to the European Commission’s public consultation on the functioning of the commodity derivatives markets, with a focus on the interplay between energy and financial market regulation. 

ACER believes that it is of importance to add sector-specific context to the consultation with respect to the functioning of wholesale energy markets and the specifics of Regulation No 1227/2011 on Wholesale Energy Market Integrity and Transparency (REMIT). The fundamental differences between financial and energy markets are the reason why Europe has (since 2011) a dedicated and highly successful energy-sector specific framework to ensure open and fair competition in Europe’s wholesale energy markets. 

ACER’s input to this consultation draws on many years of experience of national energy regulators enforcing REMIT, and ACER as the EU energy regulatory agency, protecting consumers and citizens from energy market manipulation and abuse (through its monitoring activities). It outlines the evolution of the REMIT framework with the revised Regulation (2024), including ACER’s evolving role as a wholesale energy market data reference centre.

Put simply, ACER’s position is that European consumers and businesses benefit enormously from the sophisticated EU-wide (REMIT) framework that protects energy markets from abuse. REMIT plays a crucial role in ensuring fairness, transparency and integrity of the wholesale energy market and as such should be the starting point for any further enhancements.

ACER’s response covers different aspects of the consultation, including:

• data aspects;
• position limits, management and reporting; and
• supervisory cooperation.

ACER recommends building on what already works well under REMIT and financial legislation, and to further strengthen the cooperation with the EU Securities and Markets Authority (ESMA) in areas such as data sharing, notifications to energy and financial regulators, coordination mechanisms and best practices exchange.

On 16 April 2025, the European Network of Transmission System Operators for Electricity (ENTSO-E) and the European Distribution System Operators Entity (EU DSO Entity) submitted to ACER a joint proposal on the national flexibility needs assessment methodology. The proposal defines: 

• the methodology for analysing national flexibility needs in electricity systems; and 
• the type of data to be gathered by system operators and in what format.

Why national flexibility assessments matter

The national flexibility needs assessments aim to support Member States in identifying their indicative national targets for non-fossil flexibility (e.g. storage, demand response), ensuring their electricity systems remain secure and efficient during the energy transition. 

How does it link to the EU-wide flexibility assessment and what are the next steps? 

ACER has three months, until 16 July 2025, to approve or amend the system operators’ proposal. Once approved, the methodology becomes binding for national assessments. Based on the national assessments (to be delivered by the national designated entities by July 2026), the Member States must set their national non-fossil flexibility targets within 6 months (by January 2027).

ACER will then review the national reports (by July 2027) and may provide recommendations on issues of cross-border relevance (including on removing barriers) to ensure sufficient non-fossil based flexible capacity is in place. 

In parallel, to complement the national assessments, ACER is working on an EU-wide flexibility needs assessment, which will be published by July 2027.