Failures Detected in Grid Operations
In a statement, the CNMC said it had identified “various indications of failures, some maintained over long periods, that would have affected the functioning of the electricity system and could constitute administrative infringements.” The authority clarified that the opening of these proceedings does not mean it is attributing “the origin or cause of the blackout to the companies concerned, given that the incident has a multifactorial origin.” The CNMC did not specify what sanctions the companies under investigation could face. This regulatory dimension reflects a broader European trend of heightened scrutiny of electricity markets, illustrated by the €3.8 billion in electricity subsidies the European Union approved for German industry.
The proceedings target both a transmission system operator and some of Spain’s largest electricity producers and suppliers. Red Eléctrica Española, which manages the national transmission network, sits at the center of the regulatory action. Repsol, Naturgy, Iberdrola and Endesa are also named, though the CNMC has not specified the individual role attributed to each company.
An Investigation Lasting Up to Eighteen Months
The proceedings can last between nine and eighteen months, according to the CNMC. They fall within an administrative framework that could result in sanctions, the nature and amount of which have not been specified. The authority notes that the objective of these investigations is to examine compliance with regulatory obligations, not to determine the technical causes of the incident.
The outage that occurred on April 28, 2025 caused a widespread blackout at 12:33 (Spanish time), paralyzing the entire Iberian Peninsula. The incident triggered major disruptions: no electricity, no internet, no mobile network, no traffic lights and no payment terminals. Spain and Portugal were simultaneously affected.
A “Perfect Cocktail” of Factors According to European Experts
A group of European experts published their final report on the causes of the incident in March. According to the document, an overvoltage phenomenon — a common event but this time out of control — triggered a “perfect cocktail” of multiple adverse factors that caused the blackout. The multifactorial characterization of the incident raises complex questions about the attribution of individual liability within the proceedings initiated by the CNMC.