On April 28, 2025, shortly after noon, Spain and Portugal experienced a massive blackout that left millions without power. This incident marked one of the largest outages in recent European history, as the electricity grid faced an unprecedented failure, prompting urgent investigations into its causes.
According to Red Eléctrica de España (REE), the grid operator, the blackout occurred when the frequency of the electricity supply dropped below the standard 50 hertz. This sudden drop triggered an automatic safety mechanism that disconnected the interconnection with France to prevent further damage across Europe. Approximately 15 gigawatts (GW) of electricity generation were lost, accounting for nearly 60% of energy consumption at that moment.
As darkness fell across the Iberian Peninsula, technicians at REE scrambled to understand the cause of this catastrophic event. Initial theories suggested that incidents at two photovoltaic plants in southwestern Spain might have been responsible. However, REE President Beatriz Corredor later clarified that it was inappropriate to link the blackout directly to renewable energy sources. “Everything that happens in the electrical system is recorded. So, with complete certainty, we’ll be able to know where and what caused the blackout,” she stated.
Experts were surprised by the failure of the automatic mechanisms that usually contain such outages, allowing the blackout to spread across nearly the entire region. “The failure of a photovoltaic plant, however large, doesn’t seem likely to be the cause of the collapse of the entire electricity system,” commented Pedro Fresco, general director of the Valencia Energy Sector Association.
Despite fears stemming from the 2022 energy crisis, when predictions of widespread blackouts failed to materialize, the reality on April 28 was different. Demand was not particularly high, and solar energy was operating at near full capacity, covering almost 60% of consumption. The combined output from wind and nuclear energy further bolstered the grid.
However, the incident has sparked a fierce debate over Spain's energy model. Conservative newspapers like ABC and El Mundo have criticized the government's push for renewable energy, arguing that the lack of nuclear power stations has left the grid vulnerable. They highlighted warnings from REE's parent company, Redeia, which cautioned in its 2024 financial report that the high penetration of renewable energy without adequate technical capacity could lead to severe production cuts.
In response, Prime Minister Pedro Sánchez defended his government’s energy strategy, emphasizing that linking the blackout to the absence of nuclear power was misleading. “Those who link this incident to the lack of nuclear power are frankly lying or demonstrating their ignorance,” he asserted during a news conference. He argued that nuclear plants had posed a problem during the blackout, as significant energy had to be diverted to maintain their stability.
Amidst the political fallout, the cause of the blackout remains unclear. Spain's top criminal court has opened an investigation to determine if the outage was an act of computer sabotage, although REE has ruled out a cyberattack. Investigators have pinpointed two separate incidents occurring just one and a half seconds apart, which may have affected solar power production.
The electricity grid's resilience has come under scrutiny, particularly as solar and wind energy accounted for nearly 40% of Spain's electricity last year, a significant increase from 20% in 2014. As the government plans to phase out nuclear power by 2035, the reliability of the current energy mix is being questioned.
Ecological Transition Minister Sara Aagesen stated that it was “imprudent to speculate” about the cause of the blackout, emphasizing that the system had functioned well under similar demand and energy conditions in the past. However, experts like Javier Revuelta from Afry consulting have stressed the need for a thorough analysis of how renewable energy sources perform under stress.
The incident has highlighted the challenges posed by the increasing reliance on renewable energy. “The penetration of wind and, above all, solar power, when it is massive, creates challenges in the management of the electricity system,” noted Óscar Barrero from PwC. He suggested that there may be a need for more synchronous backup power, not only during peak demand but also when there is surplus electricity.
As Spain works to restore confidence in its energy system, the importance of energy storage solutions, such as large-scale batteries, has become evident. These technologies could help mitigate frequency drops and improve grid stability. Experts argue that enhancing interconnections with neighboring countries is also crucial, as the Iberian Peninsula is effectively an energy island with limited connections to the rest of Europe.
By nightfall on April 28, power had been restored to most areas in Spain and Portugal, a relatively quick recovery considering the scale of the outage. “The restoration of service during this blackout has been impeccable,” remarked Luis Atienza, former president of REE, comparing the response favorably to past blackouts in Italy and the northeastern United States.
Looking ahead, the incident serves as a wake-up call for Spain's energy sector, prompting discussions on the need for improvements in infrastructure and technology. As industry experts continue to analyze the events leading to the blackout, the lessons learned could shape the future of energy management in Spain and beyond.
In the wake of this event, the question remains: could such a blackout happen again? While zero risk is unattainable, experts believe that the probability of a similar incident occurring has decreased as the industry reassesses its practices and protocols.
