The unfinished puzzle of the great blackout

MadridAlmost a year ago, the Iberian Peninsula was plunged into darkness for hours. What initially seemed like a daily problem –"did the fuses blow at home?", some wondered– escalated when traffic lights, metros, and social services like hospitals lost power. This also happened when mobile communication stopped working or worked very little, and radio became almost the only channel to try to figure out what was going on. The State suffered an electrical "zero electric", meaning a total collapse of the electrical system: "We estimate to restore supply in about 6 to 10 hours", announced Red Eléctrica, the Spanish electric system operator. In some areas, power was not restored for up to 12 hours.

A year later, reports have been published about the blackout, investigations have been opened, and various measures have been approved to strengthen the electrical system. Some are more immediate, such as the way the system is operated by the operator, Red Eléctrica. Others are still in their infancy and, in fact, have not materialized: developments of current regulations, the promotion of self-consumption... Nevertheless, things have been learned about the incident, such as the sequence of events. But other questions still have no answer or, at least, no clear answer: Could it have been avoided? Did someone not act as they should have? Who? The President of the Spanish Government, Pedro Sánchez, appeared the day after the blackout assuring that "responsibilities" would be demanded. A year later, this is where we are:

Three reports

The first official responses regarding the electric incident facts began to be obtained two months later. In June 2025, three reports were published: that of the Spanish government committee for the analysis of the blackout; that of the Directorate General of Operation of Red Eléctrica, and finally, that of the employers' association Aelec, the association that brings together some of the main companies in the sector.

The State distributed the blame between the operator and the sector companies, pointing to multiple factors. For its part, Aelec pointed to Red Eléctrica, and the system operator pointed to the companies. This clash between companies and operator has been witnessed live in the investigation commissions on the blackout opened in the Senate, where the PP has an absolute majority, and in Congress. A report has already been published from the first, while the commission in Congress has just started now.

In the case of the Senate, the appearances have been marked by the clash between PP deputies and the president of Red Eléctrica, Beatriz Corredor. At the same time, Corredor maintains an open dispute with the companies, with whom the relationship has become strained over time. One example is the legal battle with Iberdrola. The electricity company has taken the leadership of Red Eléctrica to court for the management on the day of the blackout, but also for having pointed them out. To understand the clash, one must look at the Extremaduran photovoltaic plant Núñez de Balboa that Iberdrola has in Badajoz. Corredor has suggested, without naming it directly, that an "experiment" was being carried out there, but Iberdrola denies that the problem originated there.

In all of them, causes were noted that the European committee of experts also identified later and which are summarized as follows: there was a rapid and uncontrolled increase in tension. The control mechanisms for this tension did not work. And finally, a cascading loss of electrical generation occurred, which led to a disconnection of the system. That is to say, to zero electricity.

The European verdict

The European verdict of the European Network of Transmission System Operators for Electricity (ENTSO-E) –a report of hundreds of pages that provides an almost millisecond-by-millisecond technical description of what happened– also concluded that the blackout was the result of "multiple factors [...] interconnected": voltage oscillations, cascading generator disconnections, and overvoltages. What we know for sure, different experts agree, is that "a button was not pressed and everything blew up".

"The entire sequence of events is very detailed and I doubt that we can go any further," indicates Diego Rodríguez, professor at the Complutense University of Madrid and researcher at Fedea, an energy expert, who adds that although the European group does not delimit responsibilities, it does point out that the system "was not strong enough" to face the succession of events of that day.

And it is precisely in this delimitation of responsibilities – that is, who was to blame – where the focus is now placed and where the involved parties are already looking with attention, especially because in the future, which everyone assumes will be distant, it is what can determine who pays the broken plates: the claims.

The Competition files

This ball is on the roof of the National Commission on Markets and Competition (CNMC). The body chaired by Cani Fernández is not only investigating who was responsible for what happened, but can also impose sanctions. For now, it has already opened a series of sanctioning proceedings (the latest this very Friday) against different companies, but also against Red Eléctrica. "It has to see if the former did not provide the service they should have, or if the system operator [Red Eléctrica] was not diligent enough in the programming and the orders it should have given that day to the companies," reflects the expert.

The CNMC, which in parallel has launched a working group to propose measures to strengthen the electricity system, has 18 months to resolve the proceedings. For the moment, Red Eléctrica faces "very serious" faults, while private operators face "serious" faults.

What is finally decided will be key for those who go to court to be compensated for the impact of the blackout. Insurers, for example, can claim on behalf of affected households or businesses – such as supermarkets – that had coverage for such an incident. Customers who, on their part, did not have insurance can claim from the marketer, who will surely then point to the distributor and finally to the energy generating company. In parallel, large industry is also looking to the courts. Repsol or Moeve have even quantified the impact of the blackout on refineries.