What are bidding zones and why the need to review them?
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 bidding zone review. The report, which assesses 14 electricity bidding zone configurations across Central and Northern Europe, is intended to support 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.
As part of its mandate under the ACER Regulation, ACER will also publish an Opinion to assess whether 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.
Following the publication of the TSOs’ bidding zone report, Member States have six months to decide whether to amend the existing bidding zones.
