Lisbon, Oct. 3, 2025 (Lusa) — The Iberian blackout on 28 April was caused by a succession of sudden shutdowns of renewable production and subsequent loss of synchronisation with the continental European grid, according to the panel of experts investigating the incident.
The report published on Friday, drawn up by 45 experts from network operators and regulators from 12 countries, classifies the incident as "scale 3", the most serious level provided for in European legislation, and describes it as "the most significant to have occurred in the European electricity system in more than 20 years", affecting millions of citizens and causing serious disruption to essential services.
According to the analysis by the European Network of Transmission System Operators for Electricity (ENTSO-E), the sequence of failures began at 12:32 pm (Brussels time), when several solar and wind power plants in southern Spain suddenly disconnected from the grid, followed by additional losses in regions such as Granada, Badajoz, Seville, and Cáceres. In less than a minute, more than 2.5 gigawatts of production capacity were removed. This shortfall reduced the available reactive compensation, resulting in a surge in electrical voltage and triggering a cascading effect throughout the Iberian Peninsula.
At 12:33 p.m., the Iberian system began to lose synchronisation with the continental grid, registering frequency and voltage oscillations that could not be stabilised by Portugal and Spain's automatic defence plans. Shortly afterwards, the interconnections with France and Morocco were also disconnected, completing the electrical separation of the Peninsula and the total collapse of the Portuguese and Spanish systems.
The conclusions released today are factual and based on data collected up to 22 August.
The final report, initially scheduled for October 2026, has since been brought forward to the first quarter of 2026 and will include concrete recommendations aimed at preventing similar incidents not only on the Iberian Peninsula but throughout the European electricity grid.
SCR/ADB // ADB.
Lusa
