CNMC finds power plant failures and outdated plans in grid restoration after 2025 blackout

Spain's National Markets and Competition Commission (CNMC) has published the results of its inspections of the restoration capabilities of the peninsular electricity system following the blackout of 28 April 2025. The report (INF/DE/155/26) was approved on 30 September by its Regulatory Supervision Chamber and released on 20 October, according to Vozpópuli and El Periódico de la Energía. The inspections were carried out under Royal Decree 997/2025.

The review covered nine hydroelectric plants with black-start capability that took part in the restoration and one distribution company; their names are confidential. According to the report, most of the units started up autonomously as planned, but some did so late because of technical problems, others supplied loads well below their technical minimum, which caused instability and disconnections, and the energisation of transformers tripped protection systems. Some units designated to begin the restoration were not available on the day of the blackout.

At the distribution company, remote control of substations was lost at times and crews had to be sent out, and communications between control centres were intermittent, although alternative channels prevented contact from being lost entirely. Most of the restoration plans date from 2016 and 2017.

The CNMC recommends updating those plans regularly, establishing communication protocols, moving from individual start-up tests to progressive restoration tests and coordinated simulations, and periodically reviewing and certifying these capabilities. The regulator warns that its conclusions cannot automatically be extrapolated to the generation fleet as a whole and says it will extend the inspections to combined-cycle plants and other technologies, including renewables.