The ENTSO-E Expert Panel’s factual report into the 28 April blackout that plunged continental Spain and Portugal into darkness has shed light on the sequence of events that led to the most serious power system event in Europe in over two decades. The investigation revealed that the incident began at 12:33 CEST when voltages in southern Spain surged sharply, spreading into Portugal and triggering a cascade of generator trips. This rapid frequency decline caused the Iberian Peninsula to lose synchronism with the rest of the Continental Europe synchronous area within a mere five seconds. Interconnections to France and Morocco tripped shortly thereafter, culminating in a complete system collapse by 12:33:24.
Despite the activation of automatic system defence plans, they proved insufficient to prevent the full outage. Restoration efforts were a mix of re-energisation from France and Morocco, coupled with black-start hydropower initiatives in Spain and Portugal. Portuguese supply was restored by 00:22 on 29 April, while Spanish supply was fully reinstated by 04:00 the same day.
The report noted that the Iberian system had been operating normally prior to the incident, with regional coordination centres identifying no security risks and the grid considered “N-1 secure”. The panel highlighted that this event marked the first time in the Continental Europe synchronous area that a combination of cascading generator disconnections and voltage rises triggered a system-wide blackout.
The findings have sparked a call to action from industry groups. SolarPower Europe, UNEF, and APREN welcomed ENTSO-E’s report, emphasising that it underscores a lack of voltage control as a key system condition at the time of the incident. They pointed out that renewables were not legally permitted to contribute to voltage control until Spain updated Operational Procedure 7.4 on 12 June 2025. The organisations stressed that the full implementation of the new rules in the coming months would enable a more robust system.
In a joint statement, they asserted, “The Iberian blackout must be a moment of learning. These technologies are already available and should be procured to further support stable voltage levels, managing variability, and delivering renewable-powered energy security.” They reiterated calls for greater investment in system stability and flexibility, including allowing renewables to provide dynamic voltage control and integrating battery storage and grid-forming inverters.
The incident and subsequent report raise critical questions about the resilience of Europe’s power grid and the role of renewable energy in maintaining system stability. As ENTSO-E prepares a final report for the first quarter of 2026, which will provide a root-cause analysis and recommendations to prevent recurrence, the sector must grapple with how to integrate renewable energy sources more effectively into the grid. The Iberian blackout serves as a stark reminder of the vulnerabilities in the current system and the urgent need for innovation and investment in grid stability technologies. The coming months will be pivotal in determining how Europe can bolster its energy infrastructure to prevent such incidents in the future.