According to Deutsche Welle, the recent large-scale blackout in Spain and Portugal was caused by 'overvoltage.' Overvoltage refers to a situation where the voltage within the grid is too high, causing protective systems to shut down parts of the grid, resulting in outages. Spain's Minister for Ecological Transition, Sara Aagesen, stated in Madrid on June 17 that there was 'insufficient voltage regulation' on the day of the blackout.

She pointed out that theoretically, the Spanish grid is stable enough to handle such situations, but overvoltage led to multiple power plants being disconnected, triggering further outages. Aagesen mentioned that some energy companies improperly disconnected their plants from the grid to protect their facilities. She indicated that the Spanish grid operator REE also played a role.

Aagesen emphasized that REE had not planned enough conventional power plants, as traditional turbine plants are better at regulating overvoltage than most photovoltaic or wind farms. She also stressed there is no evidence suggesting that this was a network attack. On April 28, the entire territory of Spain and Portugal experienced a blackout, causing significant disruption to transportation and telecommunication systems. The south of France and Morocco were also briefly affected. This incident marks one of the largest blackout events in Europe to date.