General – Blackout
The most dangerous blackout in history, which brought down the grids of Spain and Portugal, was caused by a disconnection between Spain and France, i.e. between the Iberian Peninsula and the EU.

According to REE, the operator of the Spanish grid, yesterday’s giant blackout, one of the most spectacular failures of European energy systems in the age of electrification, was caused by the sudden disconnection between the Spanish and French electricity grids.
For the operator, the loss of power that hit the Spanish grid at 12.33 CET, the cause of which is still unknown, caused such a huge imbalance on the grid that the Spanish grid was cut off from the French grid and thus from the EU.
This, in turn, led to the total collapse of the Spanish grid and, as a result, the collapse of the Portuguese grid.
Although some solar, wind and thermal generation remained operational in the Iberian Peninsula, even in the immediate aftermath of the drop in electricity distribution and transmission, the inability of the grid to compensate for intermittent generation through the connection with the EU determined the loss of an abysmal amount of electricity generation.