Spain needs urgent action on voltage control to avoid repeat of April blackout, says regulator

Spanish regulator CNMC has called for “urgent, provisional measures to stabilise the system before a more permanent solution can be found”, to prevent a repeat of the April 28^th outage which cut electricity across Spain, Portugal and parts of France.

The alarm was raised after a report from Spain’s grid operator REE to CNMC that it had detected steep voltage swings over several weeks recently, similar to those which are believed to have triggered the April blackout.

Meanwhile, the European Network of Transmission System Operators for Electricity (ENTSO-E) has published its initial findings on the causes of the disaster.

It confirmed that “the massive power outage that hit the Iberian Peninsula on April 28 was the first known blackout caused by excessive voltage”, adding to evidence from other inquiries that a surge in voltage was the immediate culprit.

Regarding REE’s latest warning to CNMC, ENTSO-E said: “The rapid voltage fluctuations recorded, even though the voltages are always within the established margins, can potentially trigger demand and/or generation disconnections that end up destabilising the electrical system.”

Final report due Q1 2026

The final report of ENTSO-E’s Expert Panel is expected in Q1 2026. It will make recommendations aimed at preventing future similar incidents across the whole European power system, including:

• Voltage management instruments available
• Assessment of grid users’ behaviour in voltage control and disconnections
• Performance of the system defence plan and possible improvement
• Analysis of the various steps of the restoration phase
• Data exchange with stakeholders to enhance relevance and accuracy of system operation