The “APE – Appunti di Energia (Energy Notes)” series continues with a new issue dedicated to the blackout that, on April 28, 2025, affected Spain, Portugal, and part of France. Emanuele Ciapessoni, Leading Scientist, and Diego Cirio, Head of Research Group, lead us through the causes, dynamics, and lessons learned from an unprecedented event in an electricity system with a very high penetration of non-programmable renewable energy sources, offering hints for comparison with the Italian situation.

The analysis retraces the technical and regulatory context, and the phases of the incident that led to the loss of about 30 GW of load. The perspectives of grid operators, regulators, and generation plants are reviewed, highlighting the lack of participation in voltage control by renewables and other structural weaknesses.

The document compares the countermeasures adopted in Spain and Portugal with the Italian framework, stressing how grid investments, stricter technical requirements, and advanced stabilization systems make the Italian system better equipped today to face similar events.

Finally, the paper opens a broader reflection: the increasing complexity of electricity grids calls for innovative approaches to risk management, by introducing probabilistic methods and reviewing criteria and practices once considered consolidated. The ENTSO-E analysis is still ongoing, but the Iberian blackout is already a crucial test case for the future of power system security in Europe.