The massive blackout was caused by a "surge cascade" and not by renewable generation.

BarcelonaThe great total power blackout (blackout) recorded in Spain and Portugal on April 28 was a unique event in the world and was due to a "surge cascade" that began in the south of the state and spread throughout Spain and Portugal within minutes, according to the technical report published today by the European Network of Transmission System Operators. However, the report does not point to blame and makes it clear that "the problem here is not that there were renewables, but that we need generation that has voltage control."

"The good news is that it can be done just like with traditional generation," explained the president of Entso-E, Damián Cortinas, when asked about the responsibility of green generation sources. This blackout has been described as "the most serious in Europe in the last twenty years" and the first under a kind of "cascading surge," although he avoided pointing fingers.

Voltage is the level of energy and must be maintained within certain limits. A classic cause of a blackout is a voltage drop due to an imbalance between supply and demand. "A voltage problem must be resolved locally, close to where it occurred. This means you need the capacity to regulate it within the system. It's a very old technology; it's nothing new. We have to see if the control voltage level required by most countries is sufficient today," Cortinas added.

The massive blackout was caused by factors such as the sudden disconnection of several renewable energy facilities, a sharp increase in voltage, previous local fluctuations, cuts in interconnections with Morocco and France and an increase in voltage, as well as limitations of automatic defense mechanisms.

This Friday, after five months of collecting data from governments and actors involved after the blackout, the European Network of Transmission System Operators for Electricity (Entso-E) has presented its "factual" report, with which the organization seeks to offer "a technical and objective explanation of what happened" by compiling the facts. However, this report will not be definitive, as the organization is working on a final report, expected to be published in the first quarter of 2026. This report will provide a detailed analysis of the root causes and recommendations for preventing future similar incidents in the European electricity system.

"Something like this has never happened in Europe, and we know it for sure," Damian Cortinas told the press regarding this cascading surge effect that caused the collapse of the peninsular electrical system. "This is new. That's why we also need time to analyze what happened and what could happen. But it is something new. This cascading surge effect that causes a total blackout has never been seen in Europe. And, of course, a total blackout in two countries has significant repercussions for citizens and society," he said.

No blame pointed.

In any case, Cortinas makes it clear that the objective of this report, carried out by a panel of 45 experts from transmission system operators—including the Spanish operator Red Eléctrica de España (REE)—and regulatory authorities from across Europe, and based on extensive data collection from generating units, is not to point fingers, a "technical and objective" explanation of what happened.

"Entso-E's role is not to attribute liability to any party. That is not our mandate. We are not a police agency. We are not a judicial body. We know that liability issues are very serious, especially in Spain. That is not the objective of this report. That is something the Spanish authorities will assign when it arrives."