The Iberian Peninsula experienced a major power outage on April 28, 2025, leaving Spain and Portugal without electricity for several hours. The blackout, one of the most severe to occur in Europe in twenty years, triggered a major crisis directly affecting millions of inhabitants, disrupting transportation, schools, and industries. A detailed report published on June 17 by the Spanish government finally clarifies the multiple causes that led to this unprecedented event and identifies the technical responsibilities involved. This report constitutes the first complete official analysis on the subject, coming after several weeks of rigorous investigation conducted by a specialized commission appointed directly by the Spanish government.
Precise Technical Causes of the Blackout
According to Spain’s Minister of Ecological Transition, Sara Aagesen, the blackout originated from multiple voltage surges that triggered an uncontrollable chain reaction. This situation resulted from a combination of planning and assessment errors by the Spanish network operator, Red Eléctrica de España (REE). On that particular day, REE had implemented minimal voltage control measures, judged to be the weakest deployed since the beginning of 2025. To these initial errors was added the reaction of several private power plants, which automatically disconnected their units to protect their installations, exacerbating the network’s critical situation.
The phenomenon unfolded extremely rapidly, in less than one minute, as three major substations located in Granada, Badajoz, and Seville disconnected almost simultaneously. The incident thus precipitated a generalized failure of the network that extended into Portugal and isolated the Iberian Peninsula from the rest of the European grid, including connections with France and Morocco. Production capacity was almost completely lost instantaneously, plunging the entire peninsula into darkness.
Political Reactions and Ongoing European Investigation
Immediately following the incident, Spanish Prime Minister Pedro Sánchez ordered the creation of an investigative commission, urging the public not to speculate before obtaining precise results from the technical analysis. Although initially estimated to take several months, the government accelerated the process, given the significant economic and social impact of the event.
In parallel, the European Network of Transmission System Operators for Electricity (ENTSO-E) is conducting its own independent investigation. This inquiry aims to precisely determine potential consequences for the entire European network. The Spanish competition regulatory authority, the Comisión Nacional de los Mercados y la Competencia (CNMC), is also conducting an additional investigation to precisely identify responsibilities of the private entities involved.
Immediate Repercussions on Infrastructure and Businesses
The blackout had immediate and concrete consequences on the economic and social fabric of the Iberian Peninsula. Public transport services, notably rail and air, were suspended for several hours, causing logistical chaos. Industrial companies, particularly in manufacturing and technology sectors, suffered significant economic losses due to the abrupt halt of their production lines. Many schools, hospitals, and administrative offices were also forced to operate in degraded mode.
The report also emphasizes the alarming vulnerability of critical infrastructure and highlights insufficient investment in electrical network security. It formally rejects the hypothesis of a cyberattack, initially suggested by some observers.
European Financing: A Strategic Project Approved by the EIB
In response to these revelations and within the framework of a European energy resilience plan, the European Investment Bank (EIB) approved on June 16, the day before the report’s publication, substantial financing of €1.6 billion aimed at strengthening the electrical interconnection between Spain and France. This strategic project, named “Bay of Biscay,” plans a high-capacity submarine interconnection linking the Spanish Basque Country to the Nouvelle-Aquitaine region in France.
The project, jointly led by Red Eléctrica and the French grid operator Réseau de Transport d’Électricité (RTE), will directly benefit from an initial immediate disbursement of €1.2 billion, complemented by an additional €578 million subsidy from the Connecting Europe Facility fund. The clear objective is to increase the interconnection capacity between France and Spain to 5 GW by 2028, from the current 2.8 GW.
Economic and Strategic Implications of the Financing
This European investment directly addresses vulnerabilities revealed by the April blackout. It will help mitigate future risks linked to production imbalances, especially during periods of high intermittent renewable energy production. Strengthening electrical exchange capacities also aligns with the European policy of energy market integration, essential for price stabilization and continental energy security.
By dramatically increasing exchange capacity between the two countries, the Bay of Biscay interconnection is expected to facilitate bilateral energy flows and significantly enhance the resilience of the Iberian network. The project is considered strategic by both countries, which actively collaborate through their joint venture, Inelfe.
Towards a Generalized Strengthening of the European Network
The lessons learned from this historic blackout will necessarily have lasting implications for the entire European electricity sector. National regulators and grid operators will need to integrate enhanced monitoring and control mechanisms for electrical flows, and revise investment strategies to reinforce existing infrastructure and prevent future major outages.
This ambitious European financing represents a tangible model of response to critical vulnerabilities revealed by the Spanish blackout. Public and private decision-makers will now be required to adjust their energy policies and investment strategies according to the report’s technical recommendations to guarantee the robustness and energy security of the continent.
