GoKawiilSummary The final report of the Expert Panel on the 28 April 2025 blackout in continental Spain and Portugal identifies the causes of the blackout and outlines recommendations to strengthen the resilience of Europe’s interconnected electricity system. It was prepared by a technical Expert Panel of 49 members, including representatives from Transmission System Operators (TSOs), Regional Coordination Centres (RCCs), ACER and National Regulatory Authorities (NRAs), and was chaired by experts from two unaffected TSOs. The investigation concludes that the blackout resulted from a combination of many interacting factors, including oscillations, gaps in voltage and reactive power control, differences in voltage regulation practices, rapid output reductions and generator disconnections in Spain, and uneven stabilisation capabilities. These factors led to fast increases of voltage and cascading generation disconnections in Spain, resulting in the blackout in continental Spain and Portugal. Based on these findings, the Expert Panel sets out recommendations addressing each of the factors identified in the report to help prevent similar events in the future. These include strengthened operational practices, improved monitoring of system behaviour and closer coordination and data exchange among power system actors. The findings of the investigation also underscore the need for regulatory frameworks to adapt in order to support the evolving nature of the power system. The 28 April blackout was a first of its kind event, and the recommendations aim to strengthen system resilience with solutions that are already technologically deployable. This blackout highlights how developments at the local level can have system-wide implications and underlines the importance of maintaining strong links between local and European system behaviour and coordination, while ensuring that market mechanisms, regulatory frameworks and energy policies remain aligned with the physical limits of the system. Download the final report of the Expert Panel
Context On 28 April 2025, at 12:33 CEST, the power systems of continental Spain and Portugal experienced a total blackout. A small area in Southwest France close to the Spanish border experienced disruptions for a very short duration and several industrial consumers and generators were affected. The rest of the European power system did not experience any significant disturbance as a result of the incident. This was the most severe blackout incident on the European power system in over 20 years, and the first ever of its kind. Figure 1 – Geographic area affected by the incident of 28 April 2025.
Expert Panel Following the blackout, on 12 May 2025, ENTSO-E set up an Expert Panel in line with Article 15(5) of the Commission Regulation (EU) 2017/1485 of 2 August 2017 establishing a guideline on electricity transmission system operation (SO GL) and the Incident Classification Scale (ICS) Methodology. The ICS Methodology is the framework for classifying and reporting incidents in the power system and for organising the investigation of such incidents and is especially relevant to the work of the Expert Panel. It is noted that the investigation of the Expert Panel was performed in line with the version of the ICS Methodology applicable at the time of the incident. Under the legal requirements of both SO GL and the ICS Methodology, when the incident is classified according to the ICS Methodology criteria as scale 3 incident – blackout – the Expert Panel is tasked to investigate the root causes of the incident, produce a comprehensive analysis, and make recommendations in a final report, published on 20 March 2026. The Expert Panel consists of representatives from TSOs, the Agency for the Cooperation of Energy Regulators (ACER), National Regulatory Authorities (NRAs), and Regional Coordination Centres (RCCs). The Panel is led by experts from TSOs not directly affected by the incident and includes experts from both affected and non-affected TSOs. The Expert Panel is led by Klaus Kaschnitz (APG, Austria) and Richard Balog (MAVIR, Hungary). ENTSO-E Bodies Convenors participating in the Expert Panel Olivier Arrivé – as chair of the System Operation Committees
– as chair of the System Operation Committees Robert Koch – as convenor of the Steering Group Resilient Operation
– as convenor of the Steering Group Resilient Operation Rafal Kuczynski – as convenor of the Regional Group Continental Europe Experts from TSOs and RCCs participating in the Expert Panel Amprion (Germany) Tilman Ringelband EirGrid (Ireland) Donna Kearney Elia (Belgium) Bernard Malfliet Elia (Belgium) Peter Van Meirhaeghe Energinet (Denmark) Bent Myllerup Mavir (Hungary) Andras Woynarovich Red Electrica (Spain) David Alvira REN (Portugal) Filipe Ribeiro RTE (France) Laurent Rosseel SEleNe CC (Greece) Maria-Faidra Katsiantoni Swissgrid (Switzerland) Bastien Grand Terna (Italy) Guido Coletta Terna (Italy) Giorgio Giannuzzi Transelectrica (Romania) Mihai Cremenescu Experts from ACER and NRAs participating in the Expert Panel ACER Georgios Antonopoulos ACER Uros Gabrijel ACER Aleksander Glapiak ACER Maria Barroso Gomes ACER Domen Kodric ACER Zoran Vujasinovic ACER Jan Kostevc ANRE (Romania) Alina Poanta ARERA (Italy) Marco Pasquadibisceglie ARERA (Italy) Andrea Rosazza BNetzA (Germany) Jochen Gerlach BNetzA (Germany) Thomas Hoelzer BNetzA (Germany) Nicolas Krieger CNMC (Spain) Virginia Garcia Escoin CNMC (Spain) Teresa Ibanez Tarrago CNMC (Spain) Diego Roldan Cabanillas CRE (France) Martin Frédéric CRE (France) Pierrick Muller CRE (France) Sara Rami CREG (Belgium) Marijn Maenhoudt CREG (Belgium) Emilie Leroy-Biasutti EI (Sweden) Anna Carlen ElCom (Switzerland) Raffaele Bornatico ERSE (Portugal) Jose Capelo ERSE (Portugal) Paulo Oliveira ERU (Czech Republic) Pavel Simoncik MEKH (Hungary) Erika Szirmai URE (Poland) Lukasz Makos URE (Poland) Piotr Rak URE (Poland) Witold Zuchowski Expert Panel Meetings 12 May 2025
3 June 2025
23 June 2025
15 July 2025
18 August 2025
2 September 2025
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