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 has released its multi-annual programming document 2026-2028, outlining its strategic goals and priorities for the coming years, including its 2026 work programme.

Which are ACER’s priorities for 2026-2028?

ACER will continue its work on:

• the integration of EU energy markets;
• infrastructure, flexibility needs and security of supply;
• the integrity and transparency of the EU’s wholesale energy markets; and
• longer-term regulatory challenges (e.g. increasing price and geopolitical volatility, Russian gas phase out).

In 2026, ACER’s work will focus on the following priorities:

• REMIT framework to protect against market manipulation: ACER will continue to ensure that REMIT is fully implemented and hence reinforce trust that prices set in Europe’s wholesale energy markets reflect competitive forces and the underlying market fundamentals. The Implementing Regulation and delegated acts related to REMIT II will broaden the scope of market surveillance and the level of transparency of energy markets, while ACER will progressively conduct cross-border investigations, complementing national regulatory authorities’ work.
• Cross-border trade and energy security: ACER will support amendments to network codes for cross-border electricity and gas trade. In line with REPowerEU, ACER will monitor the phase-out of Russian gas imports to the EU, and contribute to key discussions on energy infrastructure, security of supply and flexibility.
• Market monitoring: ACER will continue monitoring the energy sector, identifying challenges and opportunities to increase consumer benefits from the integrated EU energy market.

The document was adopted on 12 December 2025 by ACER's Administrative Board, following the favourable opinion of the Agency's Board of Regulators.

Access previous editions.

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.

In 2024, the revision of REMIT (Regulation on Wholesale Energy Market Integrity and Transparency) introduced new data reporting requirements, including the obligation to report exposure data, which shows how much market participants are exposed to price movements in wholesale energy markets.

At the same time, broader initiatives such as the Clean Industrial Deal and the EC consultation on the functioning of commodity derivatives and spot energy markets highlight the importance  of simplifying and standardising data reporting.

As exposure data is a new and distinct reporting stream under REMIT, ACER will implement a new electronic template ‘Exposure XSD’ for its reporting, as set out in the revised REMIT and the recast REMIT Implementing Regulation.

Within this context, ACER is exploring whether the ‘ISO 20022 standard’, a common framework for exchanging data, could be applied to the ‘Exposure XSD’ reporting format, with the aim of making the reporting process simpler and more interoperable.

As a new reporting stream, the Exposure XSD is a suitable candidate that may benefit from the use of an existing standard. It is the only reporting format covered by this consultation, and no changes to existing REMIT reporting formats are being considered.

Your views matter

To support more harmonised reporting and to improve the interoperability of reported data, ACER will run a public consultation to gather input. Stakeholders are invited to share their views on the potential benefits of applying the ISO 20022 standard to the Exposure XSD reporting format. 

The public consultation will run from 12 January until 9 February 2026.

Next steps

Based on the input received, ACER will assess whether to proceed with adopting the ISO 20022 standard for the Exposure XSD electronic format.

Technical specifications and detailed guidance on how to report exposure data in line with REMIT Implementing Regulation will be addressed in a separate consultation, to be launched after the revised Regulation enters into force.

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.

Today, ACER releases its report on the Polish gas transmission tariffs directed at GAZ-SYSTEM S.A., Poland’s transmission system operator (TSO), which manages the country’s two transmission systems.

The report assesses the compliance of the proposed reference price methodology (RPM) with the requirements of the EU Network Code on Harmonised Transmission Tariff structures. 

What is the proposed tariff methodology?

The Polish TSO proposes to:

• Apply a postage stamp reference price methodology with a 50-50 entry-exit split, combined with discounts for LNG terminals, biomethane producers and gas storage facilities.
• Merge the two existing entry-exit zones of the National Transmission Network (NTS) and the Transit Gas Pipeline System (SGT), the two Polish transmission systems, into a single national zone with uniform tariff rules.
• Continue recovering allowed revenues for transmission services through capacity-based tariffs only, meaning users pay based on the network capacity they book, not the volume of gas they transport.
• Maintain the current two gas sub-systems (for low-methane and high-methane gas) within the NTS.
• Keep two non-transmission services (gas pressure reduction and gas compression) in place.

What are the key findings? 

After analysing the consultation document, ACER concludes that: 

• The proposed methodology meets EU requirements on transparency, cost-reflectivity, avoidance of cross-subsidisation, non-discrimination, volume risk and the prevention of cross-border trade distortions.
• Merging Poland's entry-exit zones will create a level playing field for all network users importing gas to the country.
• The Polish TSO considered ACER’s previous recommendations (for the NTS system and the SGT system), addressing past shortcomings and developing a methodology that complies with EU rules.

What does ACER recommend? 

ACER recommends that the Polish national regulator (URE), when adopting its final decision on the proposed methodology:

• Review the low-methane subsystem and assess costs and benefits of potential measures to better align it with EU requirements.
• Carry out some additional assessments and consider technical adjustments to fine-tune the methodology.

See all ACER reports on national tariff consultation documents.