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Glossary · Energy industry & energy transition

ACER

ACER EU regulation electricity market REMIT network codes Internal Energy Market

ACER is the European Union Agency for the Cooperation of Energy Regulators. The abbreviation derives from its English name, Agency for the Cooperation of Energy Regulators. The decentralised EU agency, based in Ljubljana, Slovenia, began its work in March 2011. It supports cooperation between national regulatory authorities, contributes to common rules for the internal energy market and monitors wholesale energy trading.

In the electricity system, ACER is neither a technical installation nor a company that generates, trades or transports electricity. Its significance arises where national responsibilities overlap: the European electricity market links trading, transmission grids and market rules across national borders. Decisions taken in one country can therefore affect prices, trading opportunities and operating costs in neighbouring countries. ACER forms a regulatory interface between the authorities involved.

Tasks and position within European energy law

The central regulation on ACER's organisation and tasks is Regulation (EU) 2019/942, as amended. ACER is to support national regulatory authorities in tasks at Union level, coordinate their cooperation and, in cases specified by law, decide on disagreements. In doing so, the agency must act independently, objectively and in the interest of the Union. It is not generally responsible for every energy-policy or energy-industry dispute.

Its fields of work include cross-border transmission capacities, market integration and the development and implementation of network codes and guidelines. Such rules address, for example, capacity allocation, system balancing and grid operation. ACER does not adopt these European legal acts on its own. It contributes to their preparation and approves certain methodologies or conditions based on them, where the relevant EU law assigns it this task.

Not every statement by the agency has the same legal effect. ACER publishes, among other things, opinions, recommendations, reports and binding individual decisions. For common methodologies it may be directly responsible or, under certain conditions, decide in place of national regulatory authorities. A lack of agreement among the national authorities is an important but not the only possible trigger. What is decisive is always the specific legal basis and the procedure it lays down.

Market monitoring and extended REMIT powers

A second central field of work is REMIT, the EU regulation on wholesale energy market integrity and transparency. It prohibits, in particular, insider trading and market manipulation and contains publication, registration and data reporting obligations. Under the applicable reporting framework, ACER receives trading data, including orders to trade, as well as information on the underlying generation, consumption and infrastructure conditions. These data make it possible to examine irregularities across individual trading venues and countries.

The revision by Regulation (EU) 2024/1106, often called REMIT II, has expanded ACER's role. Since its entry into force on 7 May 2024, ACER has had additional investigatory powers of its own for cross-border matters covered by the law. These include requests for information, on-site inspections and the taking of statements. The older notion that ACER could merely analyse data and coordinate national investigations is therefore no longer accurate.

Investigation and sanctioning must nevertheless be distinguished. Penalising established REMIT infringements is, as a rule, the task of the competent national bodies. ACER, by contrast, may itself impose periodic penalty payments under statutory conditions, for example to enforce compliance with certain decisions on information requests or inspections. Such periodic penalty payments are not a fine for the underlying market manipulation. Procedural safeguards and possibilities of judicial review also apply to investigations.

For the practical set-up of this new activity, ACER names the fourth quarter of 2026 as the intended start of its cross-border investigations. This must be kept separate from the existence of the statutory powers since 2024. This timetable does not allow the inference that a specific procedure had already been opened or concluded on any particular day in November.

Distinction from national authorities, grid operators and the Commission

ACER replaces neither the Bundesnetzagentur nor other national regulatory authorities. National tasks remain with the respective competent bodies; in Germany, the allocation of responsibilities between federal and state regulatory authorities must also be taken into account. ACER is likewise not a general complaints body for electricity bills, supply contracts or individual grid connections. Its role lies mainly in the tasks assigned under Union law and in cross-border questions.

Nor is ACER a transmission system operator or a European control centre. Responsibility for operational grid management remains with the competent grid operators. This includes system operation, switching and operational measures against congestion. The transmission system operators cooperate, among other things, in ENTSO-E. ACER monitors or assesses certain statutory activities of this association, but does not control its grids.

The European Commission and ACER also fulfil different functions. The agency works within the European legal framework in a technical and regulatory capacity. It provides analyses and recommendations, takes part in the development of rules and takes the decisions assigned to it. This gives it no general power to set political objectives, national energy mixes or all investment decisions in a binding manner.

Why cross-border rules are necessary

Electricity trading and the physical flow of electricity are not the same thing. A trade between two countries does not determine an exclusive transmission path for the energy delivered. In a meshed alternating-current grid, flows are distributed according to the electrical properties and the operating state of the grid. A trade can therefore also use lines in a third country. Joint capacity calculation and coordinated congestion management are necessary so that economic transactions do not endanger operational security.

This can be illustrated with a simplified situation: in one region, plenty of low-cost wind power is available, while demand is high elsewhere. Additional trading can displace more expensive generation. However, if the grids in between are fully loaded, electricity cannot be transmitted in unlimited amounts. It must then be clarified which exchange possibilities are securely available and how the remaining congestion is handled. Precisely such interfaces make joint regulatory procedures important.

One practical field of application is market coupling. In coupled day-ahead trading, buy and sell bids from several bidding zones are taken into account together; the available cross-zonal capacities limit the exchange in the process. Different prices can persist if these capacities are insufficient. For the interplay to work, calculation methods, data exchange, deadlines and responsibilities, among other things, must fit together. ACER contributes to the regulation of this framework but does not itself execute the exchange transactions.

Common rules do not automatically eliminate conflicts of interest. One country may benefit from additional imports, while in another additional operational measures become necessary. The benefit of trading and the cost of securing it technically thus do not necessarily arise in the same place. ACER's institutional importance lies in making such cross-border questions manageable according to common standards, rather than leaving them solely to national decisions made side by side.

Market monitoring is not price control

ACER does not set the current exchange electricity price. Market prices result, in principle, from supply and demand within the applicable market rules. Fuel and emission costs, scarcities, grid constraints and expectations can explain high or strongly fluctuating prices. A conspicuous price movement can give cause for scrutiny, but in itself it is not proof of manipulation.

What is decisive is the conduct of the participants: REMIT covers, for example, prohibited insider transactions and manipulative or misleading trading practices. In addition, separate infringements of publication or reporting obligations may occur. The distinction protects against two fallacies: not every politically undesirable price is unlawful, and, conversely, an inconspicuous price pattern does not prove that all market rules have been complied with.

Significance for the energy transition and security of supply

With weather-dependent wind and solar power generation, spatial balancing and temporal flexibility become more important. Trading can balance out regional differences, provided grid capacities are available. Storage, dispatchable generation and flexible demand can additionally help. ACER does not provide these technical resources; it contributes to the rules under which they can participate in the market across borders.

Security of supply is likewise neither exclusively national nor solely a task of ACER. National measures sit within a European legal framework and can affect neighbouring countries. ACER has tasks in particular regarding common methodologies and assessments of the adequacy of electricity supply. Capacity mechanisms and reserves are therefore not to be understood as entirely free national instruments; their design must comply with the relevant European requirements.

The limits remain important: an internal energy market means neither identical prices everywhere nor unlimited transport possibilities nor fully harmonised national rules. Likewise, a regulatory decision alone creates no additional line and no secured generation capacity. ACER stands for the institutional level in between: common procedures, traceable data and clearly assigned decisions with which a cross-border energy system can be regulated.

Sources

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Edited by eCMS on 11.11.2026 13:58

© 2026 Erik Schmidt. All rights reserved. Quotations with a link to the source are welcome.