ACER issues today its guide on benchmarking the costs and effectiveness of cybersecurity investments in the EU electricity sector.

This ACER guide is developed under the binding EU-wide network code on sector-specific rules for cybersecurity aspects of cross-border electricity flows. It aims to help national energy regulators conduct the benchmarking required by the network code.

Why is this benchmarking important?

Conducting benchmarking of cybersecurity investments will provide national regulatory authorities with an overview of:

• the costs of implementing cybersecurity controls, as well as their effectiveness and efficiency;
• prices of cybersecurity services, systems and products;
• the level of comparability of costs and functions of cybersecurity products and services. This analysis will also help identify possible opportunities to increase spending efficiency.

This will be the first EU-wide analysis on the topic.

What does ACER recommend?

ACER encourages national regulators to follow ten principles when conducting this benchmarking:

• Plan and execute benchmarking activities to ensure results can serve their intended purpose.
• Limit the scope and complexity of information to what is required by the benchmarking analysis.
• Use a consistent approach when conducting national analyses.
• Identify the stakeholders that will provide the data required by the benchmarking.
• Develop reference lists of items for the purpose of benchmarking. For example, considering assets that are relevant for Union-wide high and critical impact processes.
• Apply general accounting principles to assess the costs of benchmarked items.
• Include macroeconomic factors (e.g. inflation) in the analysis.
• Simplify how the effectiveness of investments is evaluated, considering this benchmarking assessment does not require the same level of detail as security assessments.
• Evaluate the effectiveness of cybersecurity investments following the benchmarking objectives of the network code.
• Explore different approaches for comparing the costs and functions of cybersecurity products and services.

What’s next?

From today’s publication, national regulatory authorities have one year to carry out the cybersecurity benchmarking analysis. 

Bidding zones are geographical areas where electricity is traded at uniform prices. Within a bidding zone, electricity bids and offers from market participants can be matched without the need to allocate cross-zonal capacity. Currently, most bidding zones in the EU are defined by national borders.

Under the EU Electricity Regulation, bidding zones must be configured in a way that maximises economic efficiency and cross-zonal trading opportunities, while ensuring security of supply. To achieve this, a review of the existing bidding zones was needed to identify structural grid congestions and evaluate the potential benefits of alternative configurations.

On 28 April 2025, European transmission system operators (TSOs) published their report on the electricity bidding zone review study. The report, which assesses 14 bidding zone configurations across Central and Northern Europe, is intended to support EU Member States in deciding whether to amend or maintain the current bidding zone configurations.

What is ACER’s role in the process?

ACER is responsible for setting the methodology and identifying alternative bidding zone configurations for TSOs to consider in their review.

Hence, in November 2020, ACER issued a decision establishing the bidding zone review methodology. In August 2022, ACER published a second decision on the alternative bidding zone configurations to be considered for Central Europe (Germany, France, Italy and the Netherlands) and the Nordic region (Sweden). A third decision, covering the Baltic region, was issued in December 2023.

As part of its mandate under the ACER Regulation, ACER will also publish an Opinion (addressed to the Council) to assess whether electricity system operators followed the agreed methodology in their bidding zone review study and evaluate the impact of any deviations.

What are the next steps? 

ACER aims to publish its Opinion by the end of September 2025. Update: ACER published its Opinion on 18 September 2025.

Following the publication of the TSOs’ bidding zone report, Member States have six months to decide whether to amend the existing bidding zones. If individual Member States wish to amend their bidding zone configuration, but no unanimous agreement is reached among the relevant parties, the European Commission (after consulting ACER) will have six months to decide.

ACER is establishing a new European Stakeholder Committee (ESC) on cybersecurity in the electricity sector. We invite industry associations that could offer a pan-European perspective on cybersecurity aspects of cross-border electricity flows to join. 

What’s behind this?

The Network Code for Cybersecurity for Electricity came into force in June 2024. It sets out common rules to boost cyber resilience across Europe’s power systems. It calls for ACER to coordinate stakeholder engagement, in close collaboration with the European Network of Transmission System Operators for Electricity (ENTSO-E) and the EU Distribution System Operators Entity (EU DSO Entity).

What will the cybersecurity committee do?

Through this new ACER cybersecurity committee, industry associations will cooperate with each other and with the authorities referred to in the Cybersecurity Network Code to:

• identify problems and propose improvements to the implementation of the existing cybersecurity network code;
• recommend future revisions of the network code;
• identify whether any additional risk prevention rules may be needed for the electricity sector; and
• respond to technological developments in the sector.

By tackling these points, the cybersecurity committee will help maintain a high, common level of cyber resilience in Europe’s electricity grid and adapt policy to evolving digital risks.

Who can join?

Industry associations that could offer pan-European views on cybersecurity aspects of cross-border electricity flows are encouraged to take part. It is a chance to bring your insights to the table and ensure the voice of industry shapes the future of electricity cybersecurity in Europe.

Deadline to apply is 2 July 2025, with the first meeting planned for early autumn 2025. See how to apply.

See the Terms of reference for the cybersecurity committee for electricity.

ACER publishes today its Opinion on the draft electricity ten-year network development plan (TYNDP) 2024 and the Infrastructure Gaps Identification report 2024, submitted by the European Network of Transmission System Operators for Electricity (ENTSO-E).

What is the TYNDP and why is it important?

Cross-border electricity infrastructure is key to interconnecting Europe’s electricity markets, making it easier to share electricity across countries. This is important to integrate more renewables onto the grid and achieve ambitious decarbonisation goals.

Every two years, European grid operators submit their draft EU-wide ten-year network development plan (TYNDP) to ACER for its opinion. Given the scale of infrastructure needs and that related costs are expected to make up a growing share of electricity bills, having a robust and fit-for-purpose TYNDP is key to efficient grid development.

The TYNDP is expected to play a central role by identifying cross-border energy infrastructure needs and ensuring that projects bringing the most benefit for the EU are put forward.

On 9 April 2025, ENTSO-E submitted its 2024 draft TYNDP to ACER, along with the electricity Infrastructure Gaps Identification report. Developed within the framework of the TYNDP 2024, the latter provides a pan-European view of future power system needs up to 2050, focusing on cross-border infrastructure and storage capacities. It highlights where current or planned electricity projects might be insufficient to meet those future needs.

In its Opinion 04-2025, ACER provides recommendations to be addressed by ENTSO-E to finalise its 2024 TYNDP and prepare future editions. ACER’s recommendations aim to support investment decisions and facilitate the efficient development of the European electricity grid, in line with broader EU policy goals.

What are ACER’s main findings and recommendations on the 2024 draft TYNDP?

• ACER welcomes the progress made so far and acknowledges ENTSO-E’s continued effort to introduce improvements in each new edition of the TYNDP. 

• ACER finds that the 2024 draft TYNDP generally contributes to the objectives of non-discrimination and effective competition but does not sufficiently contribute to the efficient functioning of the electricity market or ensure an adequate level of cross-border interconnection open to third-party access. 

• While recognising the complexity of the TYNDP process within its two-year timeframe, ACER notes that several of its previous recommendations remain unaddressed, including the need to improve timeliness and transparency. Other aspects, like enhancing the granularity of the information provided, also need to be addressed.  

What does ACER recommend to ENTSO-E for future electricity TYNDPs and Infrastructure Gaps Identification reports? 

• Ensure timely submission of the TYNDP and of the Infrastructure Gaps Identification report to ACER by addressing the root causes of the recurring delays.

• Conduct substantial consultations on assumptions and methodologies used, well before the drafting begins.

• Strengthen the medium-term analyses (over a 10- or 15-year horizon) to identify future infrastructure gaps and assess projects’ costs and benefits more effectively.

• Improve transparency and consistency of the information on existing grids and projects.

• Base the modelling of the electricity network on an appropriate starting grid (for the gaps analysis) and reference grids (for the cost-benefit assessment).

• Provide more granular information on infrastructure needs and gaps, including an analysis of capacity constraints within Member States’ networks.

• Improve transparency of the cost-benefit analysis (CBA) results and continue work towards full implementation of the 4th CBA Guideline.

• Ensure full compliance with ACER’s Scenario Framework Guidelines and its Opinion on ENTSOs’ draft TYNDP 2024 Scenario Report.

What are the next steps?

ENTSO-E is asked to implement ACER’s recommendations both to finalise the 2024 TYNDP and to further improve its upcoming editions.

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. 

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.