Spain Probes Europe's Worst Blackout Over Power Rule Breaches

By Michael Kern - Apr 17, 2026

The Spanish market and competition regulator on Friday opened probes into potential breaches of power sector rules as part of a wider investigation into last year's blackout in the country.

Spain's grid buckled on April 28, 2025, leaving the country, most of Portugal, and, for shorter periods of time, parts of France, without electricity.

Investigations and multiple reports have found over the past year that the immediate cause of the worst blackout Europe has ever seen in modern times was a surge in voltage.

On Friday, the Spanish market and competition regulator, CNMC, announced that it had found breaches of power sector regulations over extended periods of time that should be formally investigated, "although they do not in themselves constitute the cause of the incident."

As a result of ongoing investigations into the blackout and power sector behavior prior to, during, and after the outage, the CNMC has detected various indications of non-compliance with the power sector rules. Some of the non-compliant behavior was maintained for extended periods of time, "which would have affected the functioning of the electricity system and could constitute administrative infringements."

The new investigation into suspected breaching of the power sector rules does not imply that the watchdog is attributing the origin or cause of the blackout to the affected companies, "considering the fact that the incident had multiple causes," the regulator said.

The probes are expected to be completed within 9 to 18 months.

Last year, an expert panel of the European network of electricity transmission system operators, ENTSO-E, released its report on the April 2025 blackout.

The report highlighted "the exceptional and unprecedented nature of this incident - the first time a cascading series of disconnections of generation components along with voltage increases has been part of the sequence of events leading to a blackout in the Continental Europe Synchronous Area."

In short, the report said that excessive voltage was the driver behind the blackout.

By Michael Kern for Oilprice.com