The 28 April blackout: 64 cases and reactive power still unmonitored

The 28 April blackout leaves 64 cases and reactive power still half-fixed

On the night of 15–16 July 2026, with the season's third heatwave bearing down, Red Eléctrica twice activated the active demand response service. Steelmakers, cement plants and chemical firms shut down their furnaces so the grid would not collapse. More than a year after the 28 April 2025 blackout, the Iberian Peninsula still needed patches: a mainland coal plant was restarted and a nuclear reactor was out of service after a minor incident. The report is closed; the problem is not.

From 472 pages with no names to 64 cases in two and a half weeks

On 28 April 2025 the Iberian Peninsula went dark in an overvoltage cascade, the first of its kind in continental Europe. 2,000 MW lost in 20 seconds and total collapse at 12:33:24. The system had warned beforehand: on 16, 22 and 24 April there were serious overvoltage episodes and no one corrected the protection settings.

ENTSO-E published its final report on 20 March 2026, 472 pages, a day after the CNMC's. The document anonymises all installations and states in writing that it does not assign responsibility. That same text documents the failures with surgical precision.

The CNMC (Spain's competition regulator), which does have sanctioning powers, has moved. On 18 April it peine the first batch: a very serious infringement for Red Eléctrica alone, with fines of up to €60 million, for failing to schedule balancing services for the generation mix it knew it would have that day. Iberdrola, Endesa, Naturgy and Repsol received cases for serious infringements. Two and a half weeks later the tally was 64 cases, with Iberdrola above twenty, Endesa on 17 and Naturgy on 11.

Why Cofrentes and Almaraz are facing the very serious infringements

The three very serious infringements are not symmetrical. REE is criticised for not using the tools it already had. Cofrentes (Iberdrola) and Almaraz's owner company (Iberdrola, Endesa and Naturgy), by contrast, are being investigated for reducing production or supply without authorisation, a different area from the technical one.

And there is a front nobody had sniffed out: the CNMC is investigating the company that operates Vandellós and Ascó for allegedly submitting bids with abnormal values to alter generation dispatch. In other words, alleged market manipulation detected in the wake of the blackout but referring to other days or periods. If confirmed, the investigation will have uncovered practices the regulator would not otherwise have seen.

Why is the rule that prevented renewables from providing voltage control still half-done?

Here is the most widespread misunderstanding. Renewables did not cause the blackout, but neither are they incapable of controlling voltage: modern inverters have done so for more than a decade and the harmonised European grid code formalised it in 2016. The problem is that Spain's P.O. 7.4 (grid operational procedure), not updated in 25 years, obliged them to operate at a fixed power factor.

Meanwhile, those that were obliged to provide voltage control —combined-cycle plants, hydro and nuclear— had been operating for hours below 75% of their reactive power setpoint, according to ENTSO-E, and neither Red Eléctrica monitored it in real time nor was anyone penalising them.

Power Electronics, Spain's largest inverter manufacturer, with €1.3 billion in revenue, said it bluntly: the rules still do not allow its equipment to provide voltage control a year later. And it added the uncomfortable comparison: Germany moved to batteries the next day. The decree amending RD 413/2014 (Spain's royal decree) gives renewables an active role in voltage control. The first step, late.

The emergency patch using combined-cycle plants costs more than €1 billion every quarter. Electricity bills have risen and no one has been declared responsible. With 64 cases open and three very serious infringements, the question is no longer who blacked out the peninsula, but how long a grid can be sustained by switching on exactly what was about to be switched off.