UK–EU ELECTRICITY TRADING FRAMEWORK POST-BREXIT

Introduction

Brexit fundamentally changed the legal structure governing electricity trade between Great Britain and the European Union. Since 1 January 2021, Great Britain has no longer participated directly in the EU Internal Electricity Market (“IEM”) or its integrated market-coupling mechanisms. Cross-border electricity trade nevertheless continues through physical interconnectors linking Great Britain with France, Belgium, the Netherlands, Ireland and other neighbouring systems. The principal legal framework is now the EU–UK Trade and Cooperation Agreement (“TCA”), domestic electricity regulation and bilateral/interconnector trading arrangements. The UK and EU are also negotiating closer electricity-market participation following negotiations launched in 2026.

Pre-Brexit Electricity Market Integration

Before Brexit, Great Britain participated in the EU Internal Electricity Market. EU market-coupling arrangements coordinated electricity prices, transmission capacity and cross-border flows through common algorithms.

Market coupling effectively allows electricity and interconnector capacity to be allocated together. Electricity therefore tends to move from lower-priced areas toward higher-priced markets without traders separately purchasing transmission rights. The European Commission describes this model as supporting competition, efficient resource allocation, price convergence and security of supply.

Post-Brexit Legal Framework

The principal framework is the EU–UK Trade and Cooperation Agreement 2020, particularly its energy provisions. The TCA established cooperation concerning electricity trading, security of supply, interconnectors and offshore energy.

After Brexit, however, existing EU single-market mechanisms ceased directly governing Great Britain–EU interconnector trading. The UK Government therefore introduced alternative arrangements while the parties worked toward a new trading model.

The TCA envisaged development of electricity trading based on multi-region loose volume coupling, intended to coordinate electricity-market information and interconnector capacity without restoring Great Britain automatically to the EU's ordinary market-coupling system.

Interconnectors and Cross-Border Capacity

Electricity interconnectors remain fundamental to post-Brexit trade. They allow Great Britain to import electricity when foreign generation is relatively inexpensive and export electricity during periods of domestic surplus.

Ofgem regulates GB electricity interconnectors through the licensing regime under the Electricity Act 1989.

Current arrangements are less integrated than EU implicit market coupling because electricity volumes and transmission capacity may be traded separately. The UK Government has acknowledged that this can produce inefficient flows, under-utilisation and additional complexity for electricity traders.

Northern Ireland and the Single Electricity Market

Northern Ireland occupies a distinct legal position. Under the Withdrawal Agreement arrangements, Northern Ireland continues participating with Ireland in the Single Electricity Market (“SEM”). Certain EU electricity-market rules therefore continue to apply where necessary for the SEM's operation.

Developments in 2026

The post-Brexit structure is currently evolving. Exploratory UK–EU discussions concerning UK participation in the EU Internal Electricity Market concluded in December 2025, and formal negotiations began in May 2026.

The UK Government considers more efficient interconnection important for lowering trading costs, strengthening security of supply and integrating renewable electricity. Future arrangements may therefore move substantially closer to integrated European market structures.

Case Name/Citation: R (Aquind Ltd) v Secretary of State for Business, Energy and Industrial Strategy [2023] EWHC 98 (Admin)

Facts: Aquind proposed a 2,000 MW electricity interconnector between England and France. The Secretary of State refused development consent, and Aquind sought judicial review.

Legal Issue: Whether the Secretary of State had lawfully applied the Planning Act 2008 and relevant national policy when refusing consent.

Judgment: The High Court upheld Aquind's judicial-review challenge and found legal defects in the Secretary of State's decision-making process.

Legal Principle/Ratio: Decisions affecting major electricity interconnectors must comply with statutory planning requirements, relevant policy and public-law standards.

Significance: The case demonstrates that infrastructure enabling UK–EU electricity trade remains subject to domestic administrative and planning law even though its economic function is inherently cross-border.

Case Name/Citation: BritNed Development Ltd v ABB AB [2018] EWHC 2616 (Ch)

Facts: BritNed, operator of the 1,000 MW electricity interconnector between Great Britain and the Netherlands, claimed damages arising from ABB's participation in the power-cables cartel.

Legal Issue: Whether cartel conduct had caused recoverable financial loss in the construction of the interconnector.

Judgment: The High Court awarded substantial damages for losses resulting from the cartel; subsequent appellate proceedings considered the proper measure of compensation.

Legal Principle/Ratio: Competition-law infringements affecting electricity infrastructure can generate private damages liability where legally recoverable loss is established.

Significance: BritNed illustrates how competition law, infrastructure investment and cross-border electricity-market integration intersect.

Conclusion

Post-Brexit UK–EU electricity trading operates through a hybrid legal framework combining the TCA, domestic energy law, interconnector licences and separate cross-border trading mechanisms. Great Britain currently remains outside ordinary EU electricity-market coupling, while Northern Ireland retains deeper integration through the SEM. With UK–EU negotiations underway in 2026, the legal framework may move toward substantially closer market integration, making interconnector regulation, competition law and regulatory cooperation increasingly important.