Spain's blackout blame game just won't stop – but at least wind and solar are off the hook

Spain’s politicians and power industry were still at each other’s throats this week over what caused last year’s massive power outage despite the publication of an extensive report into the incident.

The only issue the long awaited study from Europe’s electricity grid operator’s body, ENTSO-E, appears to have settled for good is that Spain’s large wind and solar fleets were not the trigger.

The April 2025 blackout was the result of a combination of “many interacting factors” with a lack of voltage control triggering a rapid voltage rise and cascade of generation disconnections, according to ENTSO-E, which cited several areas where existing rules were either not followed or were insufficient.

Speaking at a Senate hearing on Monday, Spain’s Energy Minister, Sara Aagesen, backed the findings, as well as claiming that “there was no warning, no alert, no indication that what happened on April 28 would occur”.

During the Senate hearing, Aagesen repeatedly said that “sufficient mechanisms” and regulations were already in place to have prevented the system collapse, clinging to the report’s findings that some assets did not fulfil their legal obligation or diverged from safety requirements.

The grid operator Red Eléctrica, however, has told Spanish media that it complied fully with all applicable rules before, during and after the blackout, and claimed that ENTSO-E’s report supports its view that the regulatory framework was inadequate.

The power outage, which left nearly 60 million people without electricity for approximately 16 hours, had initially spurred intense political backlash against the country’s renewable-heavy energy mix.

But ENTSO-E’s 49-member expert panel rejected that claim. Damian Cortinas, chairman of ENTSO-E’s board, said during an initial presentation of the report that the issue was not solar and wind power, but the absence of strict enough requirements for voltage control across all types of generation, both new and old.

The report found both regulatory gaps and compliance failures, without concluding either way on whether the blackout was preventable under the existing framework. But it stressed that “collecting data from third parties” in Spain, “proved more challenging” than doing so in Portugal.

“Some data remain missing, particularly for generation trips that occurred before the blackout,” the experts say in the report, adding that they were unable to determine exactly why some power plants shut down beforehand.

At the hearing Aagesen encouraged companies to be “transparent” and make the information public: “I would like to take this opportunity again in this chamber to say that, almost a year later, it would be very useful for companies, which own their own information, to make it public,” she said.

The chain of events

The crisis began roughly 30 minutes before the total blackout, when experts identified unusual oscillations in power, voltage and frequency across the grid. To stabilise the system, operators took manual steps including reducing electricity exports to France. These interventions reduced the oscillations but had the unintended effect of pushing voltage higher.

Shortly after, large solar and wind plants began reducing output in line with scheduled programmes. Under Spanish regulations at the time, these plants were not required to help stabilise voltage, only to generate electricity. So, when their output fell, they stopped absorbing the excess energy building up in the grid, making the situation worse. ENTSO-E identified this as a critical regulatory gap.

The conventional power plants that were supposed to compensate for the higher voltage, also fell short. According to the report, the rules did not require them to respond quickly in an emergency, and there were no penalties for not providing this support.

Adding to the already pressing situation, many plants across the system were misconfigured to shut themselves down at lower voltage levels than the rules required, meaning they switched off earlier than they should have, note the experts.

Another fact highlighted in the report is that unlike the rest of Europe, Spain permits its grid to run at higher voltages, which meant power plants were already close to their automatic shutdown threshold before the crisis began.

Finally, millions of small rooftop solar panels, which send no real-time data to grid operators, began switching themselves off as voltage climbed. Their disappearance was invisible to the people managing the system and added further stress at the worst possible moment.