The European Network of Transmission System Operators for Electricity (ENTSO-E) is set to release its final report by September 30, 2026, on the causes of a significant blackout.
The blackout, deemed “exceptional and severe” by ENTSO-E, resulted in Portugal and Spain being largely without electricity for over 10 hours. The immediate impacts included airport closures, transport congestions, and fuel shortages.
The incident has been attributed to a cascade of voltage increases, a technical phenomenon not previously seen in Europe.
This conclusion emerged from prior meetings of a panel of experts, including the Energy Services Regulatory Authority (ERSE) alongside operators and regulators from numerous European countries.
ENTSO-E reported that the cascade of voltage increases — noted in southern Spain during the final stages of the incident — led to abrupt production shutdowns, especially in renewable facilities. This resulted in the Iberian Peninsula becoming electrically isolated from the continental system, causing a loss of synchronization and collapse of frequency and voltage.
This kind of disruption had never before been identified as a cause of a blackout within the European grid. If confirmed, it will necessitate “in-depth analysis and investigation by all electrical system specialists of ENTSO-E” and the adoption of new measures to bolster resilience, as previously advised by the expert group.
Further expert group meetings are scheduled for October 14 and 30, November 18, and December 10.
