The wave of disciplinary proceedings for the blackout The blackout that left the Iberian Peninsula without electricity on April 28, 2025, has become one of the largest disciplinary proceedings in the Spanish energy sector in decades. The National Commission for Markets and Competition (CNMC) has been releasing information gradually, but it already has figures indicating around one hundred open cases.
The Spanish regulator, chaired by Cani FernandezIt has activated a sanctions mechanism affecting a large number of major electricity companies and several conventional and nuclear power generation facilities. Although the investigation revolves around zero electric As of the end of April, many of the detected breaches would have also occurred on other days and periods, and point to prolonged operating problems in the electrical system.
A flood of reports following the blackout on April 28
Following the incident of April 28, 2025, the CNMC initiated several information files to reconstruct what happened and verify whether the companies had complied with the regulations of the electricity sector. Based on this preliminary analysis, the agency has been transforming some of these reports into formal sanctioning procedures.
In the first section, made public on a Friday in April, the CNMC initiated 20 disciplinary proceedingsAmong them, one of a very serious nature stood out against Red Eléctrica de España (REE), the system operator, for having caused harm to the system or to other subjects, that is, for putting the security of supply at risk.
That first package also included cases classified as serious against several of the large electricity companies: Endesa, Iberdrola and Naturgy, in addition to other companies such as Repsol and BahÃa de Bizkaia Electricidad. In all these cases, the allegations pointed to technical non-compliance related to the operation of power generation plants, including combined cycle, renewable, and nuclear plants.
A few days later, the regulator launched a second wave of cases much broader. Some communications mentioned 34 new procedures, others 35, but all agree that the total number of open cases went from around twenty to over thirty additional cases, reaching around 35 new cases in that batch alone.
Up to 96 cases planned and around 100 underway
Sources close to the CNMC have indicated that the agency intends to initiate proceedings up to 96 disciplinary proceedings These investigations are related, directly or indirectly, to what happened on the day of the blackout and to the subsequent and subsequent behavior of the facilities. In practice, the sector is already reporting approximately one hundred ongoing investigations.
The explanation lies in the very structure of the generation park. In Spain, around 90 conventional power plants —including nuclear, combined cycle, and hydroelectric plants— and the CNMC has stated that virtually all of them showed some type of deviation or non-compliance within voltage control ranges. This reality has led the regulator to open investigations into a very large number of plants belonging to each company in order to understand in detail what went wrong both on the day of the blackout and on other recent occasions.
Industry sources acknowledge that, in a system of this complexity, it is common for errors to occur. operational issues and material failures throughout the year. From their point of view, the fact that more than 90 cases are recorded can be considered consistent with the size of the system and with the frequency of minor incidents that, in isolation, do not usually have major consequences.
However, the CNMC has not limited itself to noting isolated errors. The agency claims to have detected sustained breaches for extended periods of time, which would have had an impact on the overall operation of the electrical system. It is precisely this persistence of irregularities that has led to considering opening a series of investigations, beyond what strictly occurred on April 28.
The head of Energy at the CNMC, RocÃo Prieto González, plays a key role in the preparation of this package of measures, which the agency intends to have as advanced as possible before the formal appearances of its president before the parliamentary commission created in Congress to investigate the causes of the blackout.
The companies most affected: Iberdrola, Endesa and Red Eléctrica
In this regulatory offensive, most of the focus has been on Iberdrola and EndesaThe two largest electricity companies in the country are among those affected, although they are not the only ones. The distribution of cases, according to the different batches reported, clearly shows these companies playing a leading role.
In one of the broadest initiation rounds, the CNMC opened 18 cases against Iberdrola and 12 against Endesa, in addition to the five that had already been initiated against each of them the previous week. Between the two companies alone, this brings the total to more than forty proceedings, many of them related to the operation of specific power plants.
The regulator has paid particular attention to nuclear power plants managed through business associations. Among the files is one classified as very serious against the Almaraz nuclear power plant and its management company, in which Iberdrola and Endesa share ownership, as well as procedures involving the associations that operate the Ascó, Vandellós and Trillo power plants.
In parallel, Spanish Electricity Network has been the subject of a file for a very serious infraction stemming from a possible failure to perform several functions which the Electricity Sector Law attributes to it as the system operator. The file expressly cites the obligations to schedule the operation of the production facilities in accordance with market results and to react appropriately to system disturbances.
While Iberdrola and Endesa had initially emphasized that the very serious investigation into REE focused on the system operator, the CNMC has ended up also pointing the finger at the nuclear power plants in which these electricity companies participate. with extremely serious offenses related to the reduction of production capacity without authorization or to repeated non-compliance with availability obligations.
The role of other companies: Naturgy, Repsol, TotalEnergies, Engie and ContourGlobal
Although the main electricity companies take center stage, the list of companies under investigation is longer and reflects the diversity of actors in the generation and supply market. Naturgy, Repsol and BahÃa de Bizkaia Electricidad already appeared in the first round for infractions classified as serious.
In subsequent statements, the CNMC has added new names to the list, such as TotalEnergies CustomersEngie Cartagena and ContourGlobal La Rioja, all linked to combined cycle power plants or other facilities, were cited by the regulator for significant technical non-compliance. In these cases, the overall classification of the infractions was also serious, although not reaching the "very serious" level reserved for incidents that pose a risk to the continuity of supply.
Among the most unusual cases is the one opened against the Ascó-Vandellós II Nuclear Association (ANAV), in which Endesa and Iberdrola participated, for an alleged offer to the market with anomalous or disproportionate values, which would have aimed to improperly alter the dispatch of generation units or the result of the market clearing.
The CNMC has emphasized that, in all these cases, the practices in question are not strictly limited to the day of the blackout. Many of the indications detected would have occurred on different days and periods, including up to two years before the electricity blackout, which reinforces the idea of ​​an investigation that transcends the specific episode and focuses on the continued behavior of the companies.
Types of infractions: from technical errors to very serious offenses
The disciplinary proceedings for the blackout They cover a wide range of behaviors, from technical errors that have not compromised the security of supply to cases that are considered especially serious due to their potential impact on the system.
A large part of the procedures opened to generation plants fall within the scope of article 65.8 of Law 24/2013 of the Electricity Sector, which includes serious offenses linked to non-compliance with technical operating obligations. This category includes, among others, errors in generation scheduling, deviations in voltage control, or imbalances that, while not immediately jeopardizing the guarantee of supply, may affect the stability of the system.
At the most severe end of the spectrum are the cases classified as very seriouswhich refer to Article 64 of the same law. In the case of certain nuclear power plants, the CNMC has detected indications of a reduction in production or supply capacity without the corresponding authorization, as well as a possible repeated breach of the availability obligations imposed by the regulations.
Regarding Red Eléctrica de España, the very serious case is based on alleged breaches of several of its legal functions, including the correct scheduling of the generation mix for that day and the response to disturbances in the grid. The regulator considers that these actions would have constituted a harm to the system or for other subjects, which significantly increases its severity.
There is also an important nuance: when the case is classified as very serious and a risk to security of supply is identified, the final resolution The decision may fall not to the CNMC, but to the Government, given the systemic importance of the decisions to be made. This is the case with the proceedings against REE, while in the Almaraz case, since a systemic risk of the same magnitude has not been demonstrated, the authority to resolve the matter rests with the CNMC itself.
Time limits, possible sanctions and the course of the procedures
The initiation of these proceedings does not mean, by any stretch of the imagination, that the sanctions have already been determined. The CNMC insists that the opening of a procedure only indicates the existence of signs of irregularity that must be analyzed in depth, and that many of them could end up being archived if the infraction cannot be proven with the necessary forcefulness.
Once notified, the files have a maximum processing time which can vary between nine and eighteen months, depending on the severity of the infraction. During that time, the affected companies have the right to submit arguments, provide documentation, and request the taking of any evidence they deem appropriate for their defense.
To date, the regulator has not made public the specific amounts of the potential fines, which depend on the final outcome of each case. However, the Electricity Sector Law establishes that a very serious infringement can be punished with up to 60 millones de euros or with a penalty equivalent to a maximum of 10% of the offender's annual turnover. In the case of serious infringements, the limit drops to 6 million euros or up to 5% of annual turnover.
It is taken for granted in the industry that all companies will resort the sanctions they deem disproportionate or unjustified. Executives from Iberdrola and Endesa have already stated in their appearances before Congress that many of the files they have accessed relate to maintenance or operational issues which, although they may not perfectly align with the letter of the law, would have been reported to the system operator and were part of the plants' routine management.
The outcome of this process, therefore, is expected to be lengthy. Between the proceedings themselves at the CNMC, the potential intervention of the Government in some cases, and possible subsequent appeals through administrative litigation, the definitive impact of the sanctions It may take years to materialize.
A blackout of multifactorial origin under political and regulatory scrutiny
From the outset, the CNMC has stressed that the facts under investigation do not, in themselves, imply that the companies are the direct causes of the blackoutThe agency maintains that the power outage on April 28th was due to a multifactorial origin, where failures converged in different layers of the system and in different agents.
The president of the CNMC, Cani Fernández, has defended this thesis in the Congressional Committee of InquiryHe explained that the files only reflect the existence of indications of irregularities that require a more detailed investigation on a case-by-case basis. According to him, it cannot be ruled out that some of them will ultimately be dismissed once the technical data is thoroughly analyzed.
For their part, the top officials of Iberdrola and Endesa They used their appearances before Congress to emphasize that the electrical system is extremely complex and that technical failures, especially regarding maintenance, are relatively frequent. In their view, not all detected breaches should be interpreted as negligent or malicious conduct.
In any case, the blackout episode has reopened the debate about the robustness of the electrical grid and the way in which responsibilities are distributed among the system operator, traditional electricity companies, nuclear power plants, and the new players that have entered the market. The parliamentary commission and the CNMC's sanctioning process have become two parallel avenues for determining responsibility and, eventually, introducing regulatory changes, including the challenge of regulating renewable energies after the blackout.
The sector is closely following this institutional standoff, aware that the outcome is not limited to a few fines. What is at stake is the interpretation of the regulations, the level of technical requirements that will be imposed on the facilities in the future and how the risks of new incidents will be managed in an increasingly complex and electrified system.
Taken together, the succession of disciplinary proceedings, public appearances, and technical documents paints a picture in which the major blackout of April 28th has acted as a trigger for a thorough review of the operation of the Spanish electrical systemto uncover flaws accumulated over years and subject the practices of the sector's leading companies to scrutiny, with an outcome still open and implications that go beyond the economic sanctions that may ultimately be imposed. Furthermore, the episode has fueled a growing interest in solar self-consumption as a response from society to the perception of the system's vulnerability.