The final report by European experts confirms that the Iberian blackout was caused by cascading failures and recommends strengthening both regulatory frameworks and coordination between grid operators and large producers, in order to prevent similar events.
The document published this Friday, March 20, prepared by 45 experts from network operators and regulators from 12 countries, highlights again that the blackout that affected Spain and Portugal on April 28, 2025 was the “most serious and unprecedented incident in the European electricity system in more than 20 years”.
Research by the European Network of Transmission Network Managers for Electricity (ENTSO-E) concludes that the situation resulted from a combination of several interconnected factors, including “oscillations, gaps in voltage and reactive power control, differences in voltage regulation practices, rapid production reductions and generator shutdowns in Spain, as well as unequal stabilization capabilities”.
These factors led to rapid voltage increases and cascading shutdowns of renewable production, resulting in blackouts in mainland Spain and Portugal, as shown in preliminary conclusions presented in October 2025.
Based on these findings, the panel of experts presented recommendations this Friday that address each of the factors identified in the report, with the aim of helping to prevent similar events in the future.
However, they highlight that despite the unprecedented nature of the collapse, grid restoration was rapid, with Portugal fully regaining grid connection within 12 hours and Spain within 16 hours.
The list of suggestions includes measures such as strengthening operational practices, improving monitoring of system behavior and closer coordination and data exchange between participants in the electrical system.
ENTSO-E highlights that strengthening coordination between transmission network and distribution network operators – in Portugal, REN and E-Redes – and large energy producers and consumers “is essential to effectively manage complex events like this”.
“Sustained efforts to improve operational practices and information sharing will contribute to maintaining security of supply for all consumers”he says.
The research conclusions highlight “also the need to adapt regulatory frameworks to follow the evolution of the electrical system”.
“The blackout of April 28, 2025 was an unprecedented event, and the recommendations aim to reinforce the resilience of the system with solutions already technologically available”explain the experts.
“This blackout highlights how local-level developments can have system-wide implications and highlights the importance of maintaining strong links between system behavior and coordination at local and European levels, whilst ensuring that market mechanisms, regulatory frameworks and energy policies remain aligned with the physical boundaries of the system.”reinforce.
However, they highlight that monitoring the implementation of the recommendations presented does not fall within the mandate of the expert panel.
“Any responsibility for analysis, monitoring and implementation of recommendations rests exclusively with each recipient”the document reads.
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