Lisbon, Aug. 19, 2025 (Lusa) - The panel of European experts investigating the Iberian blackout of 28 April plans to publish its factual report on the incident on 3 October, almost a month before the legal deadline of 28 October.
The decision was announced in a statement by the European Network of Transmission System Operators for Electricity (ENTSO-E) after the group's fifth meeting, held on 18 August, which took stock of the investigation.
The data collection phase is "almost complete". It has allowed progress to be made on the in-depth investigation and subsequent preparation of the final report, which should be published by 30 September 2026.
Despite reporting some difficulties in obtaining "relevant and quality" information from some distribution operators and electricity generation companies, the experts emphasise that the analysis will be ready ahead of schedule. The date of 3 October will be confirmed at the panel's next meeting on 2 September.
The blackout, classified by ENTSO-E as "exceptional and serious", left Portugal and Spain practically without electricity for more than 10 hours. Closed airports, transport congestion and fuel shortages were among the immediate consequences.
Until now, a cascading voltage increase, a technical phenomenon unheard of in Europe, has been the cause of the incident.
This was the conclusion of the previous meeting on 15 July of the group of experts, whose panel includes the Energy Services Regulatory Authority (ERSE), as well as operators and regulators from several European countries.
According to ENTSO-E, the cascading voltage increases observed in southern Spain in the final phase of the incident were followed by sudden production shutdowns, mainly in renewable installations, and led to the electrical separation of the Iberian Peninsula from the continental system, with a loss of synchronisation and a collapse in frequency and voltage.
This type of disturbance had never been identified as a cause of blackout anywhere on the European grid. If this conclusion is confirmed, it will require "an in-depth analysis and investigation by all ENTSO-E electricity system experts", as well as the adoption of new measures to strengthen resilience, as the group of experts had warned.
SCR/ADB // ADB.
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