These new files are in addition to the 20 already initiated by the regulatory body the previous week. In this new round, none of the investigations are directed at Red Eléctrica. The company with the most open files is Iberdrola, with 19, of which 18 are for serious infringements and one for a very serious infringement, linked to the Almaraz Trillo nuclear power plants.

The Ascó – Vandellòs Nuclear Association has also received a file for serious infringements, related to possible maintenance errors, according to electricity sector legislation. After Iberdrola, Endesa is the second company with the most files, totaling 12, all for serious infringements. Other companies such as Totalenergies, Engie Cartagena, and Contourglobal La Rioja have each received one file.

During the investigation process into the responsibilities for the blackout that affected Spain and Portugal, the different agents of the electricity system have agreed to describe the incident as a "perfect storm" with multiple causes. Energy companies have argued that the system operator was aware of the network's tension problems due to prior warnings. For its part, Red Eléctrica has pointed to the non-compliance of electricity generation plants in controlling tension through reactive absorption.

The Spanish electricity system operator has estimated that the cost of the reinforced operation, implemented since the incident on April 28, 2025, amounts to 666 million euros. This translates to approximately 4 cents daily for a consumer with a regulated tariff and a monthly consumption of 300 kilowatts/hour. Since the blackout, the system has been operating in a reinforced mode that involves the use of more conventional generation plants, such as combined cycles, nuclear, or hydraulic, to ensure stability against any imbalance.