The Iberian blackout was a consequence of grid management, not any power source.

The blackout that took down the Iberian grid serving Spain and Portugal in April was the result of a number of smaller interacting problems, according to an investigation by the Spanish government. The report concludes that several steps meant to address a small instability made matters worse, eventually leading to a self-reinforcing cascade where high voltages caused power plants to drop off the grid, thereby increasing the voltage further. Critically, the report suggests that the Spanish grid operator had an unusually low number of plants on call to stabilize matters, and some of the ones it did have responded poorly.

The full report will be available later today; however, the government released a summary ahead of its release. The document includes a timeline of the events that triggered the blackout, as well as an analysis of why grid management failed to keep it in check. It also notes that a parallel investigation checked for indications of a cyberattack and found none.

...read more at arstechnica.com