"REN, like E-Redes, has already submitted to ERSE – the Energy Services Regulatory Authority the report on the incident of 28 April 2025, which is considered a Major Impact Incident (MII) and used this report to request classification as an Exceptional Event (EE)", an official source from the regulator told Lusa.

ERSE also points out that the decision regarding the classification of the event will be public and duly substantiated. However, taking this specific case into account, "since this is a European-wide incident, the decision may have to await the final report from the European Network of Transmission System Operators for Electricity (ENTSO-E)".

The classification of the event may be decisive for the eventual payment of compensation. If it is considered exceptional, the obligation to compensate consumers may be mitigated or even annulled.

The European Network of Transmission System Operators for Electricity is investigating the causes of the blackout, which it has classified as exceptional and serious. This panel of experts will have to prepare a factual report that will serve as the basis for the final report, to be completed by October 28 of this year.

The final report on the investigation must be published by September 30, 2026, at the latest. However, the Minister of Environment and Energy, Maria da Graça Carvalho, revealed that the president of ENTSO-E has committed to making "the greatest effort" to bring forward the conclusions of the investigation, which could be delivered within six months.