The final report of the Expert Panel investigating the 28 April 2025 Iberian blackout that plunged continental Spain and Portugal into darkness was published today. The extensive document details the technical and operational causes behind the event and sets out a series of recommendations to strengthen the resilience of Europe’s interconnected electricity system.
The investigation was conducted by a 49-member panel made up of representatives from Transmission System Operators (TSOs), Regional Coordination Centres (RCCs), the Agency for the Cooperation of Energy Regulators (ACER), and National Regulatory Authorities (NRAs). The process was chaired by experts from two TSOs that were unaffected by the incident, ensuring an independent assessment.
The Panel concluded that the blackout stemmed from a cascade of complex, interrelated factors. Oscillations within the system, inconsistencies in voltage and reactive power control, and differences in voltage regulation practices all played a part. Rapid power output reductions and generator trips in Spain, coupled with uneven system stabilisation capabilities, triggered a chain reaction that led to the widespread outage.
In response, the report sets out targeted measures to address each issue. These include reinforcing operational procedures, enhancing real-time monitoring of system dynamics, and improving coordination and data sharing among grid operators. The Panel also stresses the need for regulatory frameworks to evolve alongside a changing power landscape, where decentralised generation and higher renewable shares demand new approaches to system stability.
The 2025 event was unprecedented in its scale and speed, exposing how local system dynamics can escalate into continent-wide disturbances. The Panel’s recommendations aim to ensure that Europe’s power system grows more robust, aligning technical capabilities, market design, and policy objectives with the physical realities of the grid.
