A year has passed since the lights went out across the Iberian Peninsula, plunging 47 million people into darkness in the most significant grid failure Europe has known in over two decades. Investigations have concluded, reports have been published and proceedings have been opened — but no individual, institution or company has been held fully to account.
At 12:33 on April 28, 2025, the power systems of mainland Spain and Portugal collapsed simultaneously. Within seconds, traffic signals failed, underground trains ground to a halt and mobile networks became unreachable. Supermarkets filled with anxious shoppers while petrol stations, unable to operate their pumps, left drivers stranded. Electricity was not fully restored in Spain until the early hours of April 29 — almost 16 hours later.
The scale of the disruption was unlike anything the continent had seen in a generation. At the moment of collapse, solar energy alone was supplying close to 60 per cent of Spain’s electricity, with total renewable generation accounting for roughly 78 per cent of output. The grid was exporting power to Portugal, France and Morocco when, between 12:32 and 12:33, some 2.5 gigawatts of generation disconnected without warning.
Voltage surged beyond normal thresholds. Automatic protection mechanisms triggered cascading disconnections. The interconnection with France cut off. In under 90 seconds, the entire Iberian electrical system reached what the European Network of Transmission System Operators for Electricity (ENTSO-E) described as “total zero”.
EUROPE’S WORST IN OVER TWO DECADES
The ENTSO-E — which oversees Europe’s interconnected electricity system — has confirmed that the April 28 event was the most significant power system failure in Europe in more than 20 years. It was, in the organisation’s own words, “a first of its kind event”.
The causes were not simple. The ENTSO-E’s final report, published on March 20, 2026 after a year-long investigation by a 49-member expert panel, found a combination of interacting factors: oscillations in voltage and frequency, gaps in reactive power control, differing voltage regulation practices across generators, rapid output reductions and cascading disconnections in Spain. The Iberian Peninsula’s limited interconnections with the rest of Europe — long flagged as a structural weakness — compounded the collapse.
A parallel investigation by Spain’s own government, released on June 17, 2025, pointed specifically to the lack of sufficient dynamic voltage control capacity on the day of the blackout. It noted that some generators had disconnected before regulatory voltage thresholds had even been reached, worsening the crisis without technical justification. A comprehensive cybersecurity review, examining more than 300 gigabytes of data, ruled out any possibility of a cyberattack.
A YEAR ON, NO ONE HAS ACCEPTED BLAME
Twelve months after the event, accountability remains the central unresolved question. The Spanish government, Red Eléctrica de España (REE) — the national grid operator, known as Redeia — and the country’s electricity companies have each pointed fingers in different directions.
REE has maintained it followed established protocols and restored supply as quickly as possible. Spain’s electricity companies have disputed this, arguing that warning signs of instability were visible hours before the collapse and that management decisions in the preceding period were flawed. Prime Minister Pedro Sánchez was quick to control the narrative after the event, urging patience and discouraging speculation about the role of renewables.
Spain’s National Commission on Markets and Competition (CNMC) has opened more than 30 sanction proceedings against REE and ten other energy companies. As of April 28, 2026, none of these proceedings has resulted in a final ruling assigning responsibility.
A Senate inquiry committee, established on June 12, 2025, has heard from a series of technical experts and officials. None of the testimony has produced a definitive conclusion acceptable to all parties.
REFORMS PROMISED, PROGRESS SLOW
In response to the crisis, Spain’s Council of Ministers approved Royal Decree-Law 7/2025 in June 2025, outlining urgent measures covering grid oversight, voltage control and enhanced powers for the CNMC. The legislation was blocked by the Spanish Parliament in July 2025. Revisions remain pending.
Portugal moved more decisively. Lisbon announced a €400 million investment package for its electricity grid, including increasing battery storage capacity to 750 megawatts and strengthening supply to critical infrastructure.
At the European level, ENTSO-E’s final report outlined a series of recommendations aimed at strengthening grid resilience using technology already available for deployment. Updated operational procedures — including improved voltage control for renewable generators — have been rolled out fully across Spain as of March 2026.
Work has also begun on the “Bay of Biscay” interconnector, a new undersea cable link between Spain and France designed to reduce the Iberian Peninsula’s isolation from the wider European grid. The project is seen as one of the most important structural fixes available, though it will take years to complete.
ENTSO-E has underlined that the blackout exposed a fundamental tension in European energy policy: the drive for renewable energy integration has not always been matched by investment in the grid infrastructure and regulatory frameworks needed to keep systems stable. That lesson, experts say, applies far beyond Spain and Portugal.
For the 47 million people who spent all or most of April 28, 2025 without electricity, the anniversary is a reminder of how quickly modern life can unravel. Whether the political and institutional response has been proportionate to the scale of the crisis is a question that remains, one year on, very much open.
