When one of the largest power outages hit Spain and Portugal this week, speculation swirled over the possible causes of the blackout that disrupted daily life across the Iberian Peninsula.

While no definitive explanation has yet emerged, a report by Redeia Corporation, which owns Spain's electricity grid operator REE, has resurfaced and fueled concerns about the over-reliance on renewable energy.

“The high penetration of renewable generation without the necessary technical capacity to deal adequately with disturbances" in Spain "can lead to production cuts", the report had said.

Redeia, essentially warned in the annual financial report for 2024 about Spain’s high penetration of renewables without adequate infrastructure to manage potential disturbances, suggesting that such an imbalance could significantly affect the electricity supply.

These blackouts "could become severe, even leading to an imbalance between production and demand, which would significantly affect the electricity supply", it added.

But now top officials are pushing back.

When asked about the report during an interview with news radio Cadena Ser on Wednesday, Redeia president Beatriz Corredor downplayed its significance.

She said it was "wrong" to link Monday's giant blackout to the high level of renewable energy use in Spain.

Renewable energy production "is safe" and "linking Monday's serious incident to the penetration of renewables is not true, it's not correct," she added.

The 380-page annual financial report was merely listing a series of potential risks as it is required to do by law, Corredor said.

"Renewable energies work in a stable way, they already have mechanisms that allow them to work practically" like "conventional" technologies, she added.

In the report, Redeia warned that the "loss of firm production" due to the closure of "conventional" power plants that use gas and coal could lead to "greater difficulty in operating the system, an increase in production limitations and technical restrictions, as well as a possible impact on supply".

The report further warned of the "risk of an attack or incident affecting IT systems" which could "affect electricity supply" in Spain and "lead to costs and reputational damage" for Redeia.

Spain's top criminal court is investigating whether the blackout was "an act of computer sabotage" but REE has ruled out a cyberattack.