The great electrical blackout of April 28, 2025 continues to generate intense clash between the major electricity companies and Spanish Electricity NetworkMonths after the blackout that left virtually the entire Iberian Peninsula without power, conflicting accounts of what happened remain in the Senate, in technical reports, and within the sector itself.
In the subsequent appearances of the investigative committee, Endesa and Iberdrola have pointed directly to the system operator as responsible for a planning error and an insufficient response to prior warning signs. On the other hand, Redeia (the parent company of Red Eléctrica) insists that the problem originated in the behavior of certain generation facilities, including a large photovoltaic plant in Badajoz.
The day of zero electricity: prior warnings and cross accusations
The account that José Bogas (Endesa) and Mario Ruiz-Tagle (Iberdrola España) have brought to the Senate part of the same idea: the peninsular electrical system had been experiencing episodes of [unclear - possibly "problems"] for months before. voltage and frequency instability that had been reported to Red Eléctrica without any substantive measures being taken.
Bogas explained that, from the early hours of the morning of April 28, Endesa's teams detected “clear signs of frequency instability”with fluctuations that, according to him, were reported to the system operator more than an hour before the blackout. The response he says he received from the Red Eléctrica technicians was that “They were coming in and out photovoltaic" and that, especially in the south of the peninsula, there was not enough synchronous generation capable of correcting these imbalances.
Ruiz-Tagle agrees that that Monday was a a “particularly tense” day since the previous midnightAccording to the Iberdrola executive, there were numerous calls and formal communications warning of voltage control problems similar to those already recorded in previous weeks, including the shutdown of a Repsol refinery in Cartagena and occasional disconnections in the Adif railway network, which the electricity companies link to the same pattern of failures.
For both executives, the key lies not in a vague sum of factors, but in what they describe as “a single planning error” by Red Eléctrica: to schedule a very small number of central offices that day with the ability to dynamically manage voltage, that is, little synchronous generation (combined cycles, nuclear or hydroelectric) distributed in an unbalanced way, especially in southern Spain.
How the system collapse was triggered
During his testimony, Bogas reconstructed the technical sequence of the blackout. According to his account, Two unexpected frequency oscillations occurredOne originated from a large photovoltaic plant in the province of Badajoz, and the other was linked to the interconnection with France. Red Eléctrica reportedly corrected these deviations quickly, modifying the network topology, the exchanges with Portugal and France, and the operating mode.
The CEO of Endesa maintains that, by carrying out these maneuvers, the operator It substantially reduced the "tools" available to control tensionby withdrawing synchronous power equivalent to about twenty combined cycle gas turbines when only half a dozen were running. The result would have been to leave the system in a “situation of extreme weakness” just before the widespread collapse occurred.
Despite the fact that they have pointed out up to a dozen conventional power plants that went offline almost simultaneouslyBogas argues that, based on the data Endesa handles, all its facilities They rigorously met the safety thresholds And they didn't trip until network conditions exceeded established limits. In his opinion, for so many power plants to fail simultaneously, there has to be very severe instability in the entire system.
At the same time, Ruiz-Tagle emphasizes that April 28th was precisely the day with the fewest combined cycle and nuclear power plants dispatched, and that the geographical distribution of these power plants was especially low in the southern peninsula, the area where both the Badajoz photovoltaic plant and a good part of the recorded oscillations are located.
Both executives insist that, although renewables complicate voltage control, There are technical and operational tools to mitigate those risks, and that the ultimate responsibility for deciding which groups should operate to guarantee stability lies with Red Eléctrica, which can modify the results of the daily market by applying technical restrictions.
The Núñez de Balboa photovoltaic plant and the role of renewables
One of the most delicate points of the debate is the high-power photovoltaic plant in Badajoz identified by Redeia as the source of the 0,6 Hz frequency oscillation recorded at 12:03 PM, shortly before the blackout. In the Senate, Redeia's president, Beatriz Corredor, asserted that this installation “He behaved improperly” and that he had already had a similar incident a year earlier.
In his appearance, Mario Ruiz-Tagle acknowledged “For the first time” the plant is owned by Iberdrola He confirmed that it was the Núñez de Balboa plant, one of the largest photovoltaic facilities in Europe, with a capacity of approximately 500 MW. However, he denied that the plant was the cause of the blackout or that there had been any mismanagement or operational issues that day. According to his explanation, the plant “It only receives and accompanies the network fluctuations.”, without the capacity to cause them on its own.
The CEO of Iberdrola recalled a previous incident in March 2024, when an evacuation test using a single transformer generated a 0,8 Hz oscillation that dissipated without impacting the electrical system. For him, this precedent demonstrates that Oscillations alone are not enough to bring down the net if the system is well supported by synchronous generation and proper operation.
Power companies admit that the high penetration of intermittent renewables - wind and solar - makes voltage and frequency management becomes more complexBut they believe the problem lies not in the existence of these technologies, but in How is thermal backup and the geographical distribution of synchronous resources planned?In his opinion, “it cannot be” that similar episodes are repeated every spring and autumn without a radical change in the way of operating.
Underlying this is a broader debate about to what extent should network codes require conventional power plantsRuiz-Tagle points out that these facilities are obligated to meet technical standards in at least 75% of the samples collected by the operator, and accuses Red Eléctrica of wanting to raise these requirements to levels that the turbines could not physically withstand.
Electricity grid, reinforced operation and electricity bill
Following the power outage, Red Eléctrica has implemented a “enhanced operation” mode which has been in place since May 2025. This scheme basically consists of scheduling more synchronous groups -especially combined gas cycles- throughout the day to provide an additional buffer of stability in frequency and tension in the face of unforeseen events.
According to data provided by the operator, this reinforcement entailed a cost of between May and December about 516 million euros, equivalent to 2,18% of the total costs of the Spanish electricity system during that period. The president of Redeia, Beatriz Corredor, has argued that this method will be maintained until it is proven that “Everyone complies with the regulatory requirements for voltage control”.
The figures used by the sector, however, are significantly higher. Endesa has calculated that the reinforced operation It increases the electricity bill by around 1.100 billion euros per year.practically double what Red Eléctrica indicates. José Bogas has even described this additional cost as “a party that the citizen ultimately pays for”, as it is partly reflected in the final prices.
Ruiz-Tagle has acknowledged that Part of that price increase is already being passed on to consumers.This will be especially true for those with market-linked tariffs, while customers with fixed prices will notice it when they renew their contracts. Large industries, which suffered sudden production line shutdowns during the blackout, are another group heavily affected by these costs.
Studies such as the one from OBS Business School place The total losses from the accident are between 1.000 billion and 5.000 billion euros.This includes both direct and indirect damages, with a particularly heavy impact on large industries. Added to this are the claims being filed against electricity companies—currently, according to Bogas, for “a few million”—and the potential loss of profits for many businesses.
An increasingly renewable system with growing political tension
The blackout of April 2025 has been the trigger for a Unprecedented political-business debate on the state of the network and the way to manage an electricity mix increasingly dominated by renewables. The government, which has also prepared its own report, has pointed to both Red Eléctrica and the large companies for their role in the incident.
The Moncloa report speaks of a multifactorial episode, in which network management failures, inadequate responses from some facilities, and an insufficiently robust generation configuration converged. However, Endesa and Iberdrola reject this “collective” interpretation and maintain that The “central and determining” cause was the operator's programming with a limited number of groups with dynamic voltage control.
Bogas himself has questioned the independence of the European research of Entso-EThey consider it “bad practice” for Red Eléctrica to be part of the group analyzing an incident in which it is directly involved. In their view, the Spanish electricity system has a solid foundation and a reasonable planning framework—the PNIEC—but with a day-to-day management that has failed to adapt to operational reality.
Meanwhile, in the corridors of the sector, it is remembered that Spain became a European benchmark Following the major modernization of the grids in the 80s, the current challenge is no less significant: integrating a surge in renewable energy generation and new demands without compromising security of supply. The 2025 blackout, the first of its kind in the EU, has raised questions about whether the country is responding with sufficient foresight.
Meanwhile, Red Eléctrica maintains that He acted within the procedures and with the information available.And that the real problem was the response of certain power plants and the failure to comply with some technical requirements. The exchange of accusations, far from extinguishing the fire, keeps the controversy alive about who failed and when.
CNMC, connection permits and network saturation after the blackout
In parallel with the research into zero electricity, the National Commission of Markets and Competition (CNMC) is preparing a comprehensive audit of the access points to the Spanish electricity gridHow many have been granted or requested, at which substations, and under whose name? This is the first analysis of its kind in Spain, driven in part by the feeling that saturated and “bottleneck” network which the blackout has made even more visible.
The analysis covers approximately 800.000 kilometers of transport and distribution networkswith around 6.000 substations, many shared between different companies. The goal is to detect Overdemand for permits, potential duplication, and projects that monopolize capacity without being developed, in a context of a boom in requests for connection for both renewable generation and new large consumption: data centers, green hydrogen, large electrified industrial parks or charging networks for electric vehicles.
Preliminary data released by the employers' association Aeléc - which includes Iberdrola, Endesa and EDP - indicate that, by the end of 2024, there had More than 67.000 MW requested for new access pointsThis figure is equivalent to half of all installed capacity in Spain and well above the historical peak demand. A substantial portion of these requests corresponds to data centers and battery storage projects, in addition to urban developments, hydrogen refueling stations and electric vehicle charging stations.
The CNMC will cross-reference the data of all companies to verify if there are projects that have requested permission at multiple nodes simultaneously, whether there are old licenses that remain inactive years later, and to what extent this tangle of requests is contributing to the actual network saturation. The idea is to have a solid foundation for “clean” permits with no prospect of being implemented and, if necessary, propose regulatory changes.
This audit adds to the capacity gap mapping promoted by the Government to identify where there is real margin for connection, both in the Red Eléctrica transmission network and in the distribution networks managed by the large electricity companies. Both tools are closely linked to the debate that opened after the blackout: whether the system can absorb all the new power that wants to connect and under what conditions this should be done to avoid increasing the risks of instability.
Business reactions, market confidence, and next steps
The electricity shutdown has not only had a regulatory and political impact; it has also caused a change of attitude among companies connected to the networkReports such as Grant Thornton's indicate that around 86% of medium-sized Spanish companies They have strengthened their internal business continuity and outage response protocols. Only a minority see what happened as an isolated incident that requires no changes.
On the financial front, Endesa and Iberdrola executives emphasize that regulatory stability and clarity on responsibilities They will be key to maintaining the pace of investment in networks and generation. Both have publicly defended the need to flexibly adapt the Integrated National Energy and Climate Plan to the daily realities of the system, without questioning its objectives, but rather the way in which it is implemented.
The sector, institutions and European operators agree in demanding more robust operating protocols for highly renewable systemswith a greater focus on dynamic voltage control, rapid response to oscillations, and appropriate sizing of available synchronous power at any given time. In this context, the enhanced operation now maintained in Spain is seen as both a emergency patch as a preview of what could be the future operating standard.
In the parliamentary sphere, the Senate committee continues to hear from executives, regulators, and experts, while awaiting the completion of various national and European reports that should definitively clarify what happened on April 28. The conclusions will influence... how responsibilities are distributed, in the possible review of technical codes and in potential changes to network governance.
The battle over the narrative of the “Power Grid of the Blackout” essentially boils down to the tensions of an electrical system transitioning towards renewables at high speed While trying not to lose security or competitiveness: on one side, an operator that defends its actions and demands more investment; on the other, electricity companies that ask for clear rules, more synchronous backup and costs distributed fairly; and in the middle, companies and households that look with concern at both the risk of new blackouts and the impact of this struggle on their electricity bill.