Portugal's 15-Hour Blackout Sparks Compensation Debate After Cross-Border Outage
Portugal's Energy Services Regulatory Authority (ERSE) has not yet made any decision regarding the classification of this incident, an official source from the regulator told Lusa news agency. The source added that the publication of the report by European experts (ENTSO-E), along with "other relevant information, is being considered by ERSE in its forthcoming decision."
National grid operators had promptly requested that the incident be classified as an exceptional event, with the responsibility to justify their application, according to the authority led by Pedro Verdelho.
The classification of the incident could affect the potential allocation of automatic compensation to consumers, as provided for in the Quality of Service Regulation when limits on the number or duration of electricity supply interruptions are exceeded.
This compensation is borne by grid operators and, as a rule, automatically reflected in retailers' bills at the beginning of the year following the incident.
However, ERSE emphasizes that automatic compensation should not be confused with damages for specific losses, which depend on judicial or arbitral decisions and proof of the harm suffered.
On Friday, Environment and Energy Minister Maria da Graça Carvalho stated in parliament that Portuguese companies "can already seek" compensation for the Iberian blackout, though ERSE's decision on the event's classification is still pending.
"For the system to be complete and for us to have all the necessary information, ERSE must decide whether this was an extraordinary event or not," the minister said, adding that the government had urged the regulator to provide a "swift response."
Under the Quality of Service Regulation, an event may be deemed exceptional by ERSE—following a justified request from grid operators—if several conditions are met, including low probability of occurrence, a significant decline in service quality, and no fault attributable to the operators.
When asked about the conclusions drawn one year after the blackout, ERSE noted that it is represented in the European expert group and actively participated in preparing the report presented by ENTSO-E on March 20.
According to the regulator, the report "made it clear that all causes leading to the incident were external to the Portuguese electricity system."
ERSE added that the Portuguese system had already approved "a set of operational improvements" whose implementation enhances resilience against such phenomena.
Since 2019, the authority indicated, dynamic voltage control obligations in Portugal have applied not only to conventional generators but also to "new licensed production facilities."
But reinforcement measures have not stopped there. Further investments are planned, already submitted by REN in its investment plan, for proprietary reactive power management assets with dynamic operation, including "synchronous condensers and STATCOM systems." These devices, ERSE explained, are designed to ensure voltage control that is "continuously adaptable to grid conditions."
Regarding priority regulatory or supervisory changes, the same source stated that opportunities for improvement would be identified based on available information to make the national electricity system "as resilient as possible" to similar situations.
"The severe societal impacts of this incident necessitated identifying the root of the problem and implementing improvements—particularly those related to prevention and mitigation mechanisms for such events, as well as service restoration and necessary communication," the source added.
The report also emphasizes that "critical sectors, facilities, and services must have alternative power supply solutions to ensure operations can be maintained during emergencies. Today's technology offers solutions that can help minimize the consequences," it concluded.
Blackout struck one year ago
The blackout on April 28, 2025, originated in Spain at 11:32:57 and spread to Portugal within seconds, with the outage recorded in the country at 11:33:23.
In Portugal, grid operator REN initiated the first black start—an autonomous grid restart—just two minutes later from the Castelo de Bode dam, followed by the Tapada do Outeiro plant, one of the two facilities then capable of performing this procedure.
Normal operation of the National Electric System was restored in under 15 hours—faster than in Spain—with the transmission network fully back online by 11:22 PM on April 28 and complete restoration at the distribution level by 3:00 AM the following day.
After the blackout, Portugal strengthened its black start capacity by adding the Baixo Sabor and Alqueva plants, increasing the number of facilities capable of supporting an autonomous grid restart in the event of a power collapse from two to four.
Three months after the incident, the government unveiled a National Electric System Security Reinforcement Plan, featuring 31 measures across five key areas: network resilience and security, planning, renewable energy acceleration, critical infrastructure response, and international cooperation.
Among the announced investments were €137 million to improve grid operation and control, a 750 megavolt-ampere (MVA) auction for battery-based system services, and €25 million for pilot projects.
