ENTSO-E Publishes Final Investigation Report on Spain and Portugal Blackout with Recommendations to Strengthen European Grid Resilience

ENTSO-E Publishes Final Investigation Report on Spain and Portugal Blackout with Recommendations to Strengthen European Grid Resilience

(IN BRIEF) ENTSO-E has published the final report on the April 2025 blackout in Spain and Portugal, concluding that the incident was caused by a combination of interacting technical and operational factors rather than a single failure. The report, prepared by a multi-stakeholder expert panel, identifies issues such as voltage control gaps, system oscillations, and generator disconnections as key contributors to the outage. It sets out recommendations aimed at strengthening operational practices, improving monitoring and coordination, and adapting regulatory frameworks to better support modern energy systems. The findings highlight the interconnected nature of Europe’s electricity grid and the importance of aligning local operations with system-wide stability to prevent future large-scale disruptions.

(PRESS RELEASE) BRUSSELS, 20-Mar-2026 — /EuropaWire/ — ENTSO-E has released the final report of its Expert Panel examining the widespread blackout that affected continental Spain and Portugal on 28 April 2025, providing a detailed assessment of the causes and setting out a series of recommendations aimed at strengthening the resilience of Europe’s interconnected electricity system.

The report was developed by a 49-member panel composed of representatives from Transmission System Operators, Regional Coordination Centres, the Agency for the Cooperation of Energy Regulators, and National Regulatory Authorities. The panel was led by experts from two TSOs not impacted by the incident, ensuring an independent evaluation of the event.

The investigation determined that the blackout was not caused by a single issue but by a complex combination of interacting factors. These included system oscillations, shortcomings in voltage and reactive power control, inconsistencies in voltage regulation approaches, rapid decreases in generation output, and the disconnection of power units in Spain. Together with uneven system stabilisation capabilities, these conditions led to rapid voltage increases and a chain reaction of generator disconnections that ultimately triggered the large-scale outage across the Iberian Peninsula.

In response to these findings, the panel has outlined a set of targeted measures designed to reduce the likelihood of similar events occurring in the future. These recommendations focus on enhancing operational procedures, improving the monitoring and understanding of system behaviour, and strengthening coordination and data exchange between all actors involved in power system management. The report also highlights the importance of evolving regulatory frameworks to better reflect the changing dynamics of modern energy systems.

The analysis identifies the blackout as an unprecedented event, illustrating how localised issues can escalate and impact the broader European electricity network. It emphasises the need for closer alignment between local system operations and the wider interconnected grid, as well as the importance of ensuring that market structures, regulatory policies, and energy strategies remain consistent with the technical limitations of the system.

The recommendations presented are based on solutions that are already technologically available, providing a practical pathway for improving system resilience while supporting the continued development of Europe’s energy infrastructure.

Read the full report here.

About ENTSO-E

ENTSO-E, the European Network of Transmission System Operators for Electricity, is the association for the cooperation of the European transmission system operators (TSOs).
The 40 member TSOs, representing 36 countries, are responsible for the secure and coordinated operation of Europe’s electricity system, the largest interconnected electrical grid in the world. In addition to its core, historical role in technical cooperation, ENTSO-E is also the common voice of TSOs.

Media Contact:

Press contact: media@entsoe.eu

SOURCE: ENTSO-E