There has been no conclusive post mortem, the issue is still under investigation[0], this is a blog post by a tech company, not an authoritative agency with findings, basically speculation being used as a marketing article...

This article [1] also calls out the rumor mill about renewables being a cause:

> Political groups such as the far-right VOX – which has historically pushed back against climate action such as the expansion of renewables – also pointed to the blackout as evidence of “the importance of a balanced energy mix”.

> However, others rejected this suggestion, with EU energy chief Dan Jørgensen telling Bloomberg that the blackout could not be pinned on a “specific source of energy”:

> “As far as we know, there was nothing unusual about the sources of energy supplying electricity to the system yesterday. So the causes of the blackout cannot be reduced to a specific source of energy, for instance renewables.”

> Others have sought to highlight that, while it was possible solar power was involved in the initial frequency event, this does not mean that it was ultimately the cause of the blackout.

It's all inconclusive and the narrative that solar is the culprit is being pushed by anti-renewables, let's wait until there's an official conclusion to the investigation instead of peddling bullshit.

[0] https://www.entsoe.eu/news/2025/05/01/iberian-black-out-ents...

[1] https://www.carbonbrief.org/qa-what-we-do-and-do-not-know-ab...