The limited return of electricity to the Iberian Peninsula has revealed a more profound weakness within the area’s power infrastructure.
Monday’s extensive and rapid power outage, which halted activity across much of Spain and Portugal, has generated considerable regional and international apprehension.
Red Electrica (REE), Spain’s national grid operator, and Portugal’s E-Redes are currently investigating the precise reasons behind the abnormal oscillations detected in their high-voltage lines.
These oscillations also resulted in synchronisation failures within the interconnected power grid that extends into France.
Power generation mix key
Preliminary analysis by Rystad Energy indicates that the generation mix in each country was a key factor in both the power outage and the subsequent recovery, now that electricity has been restored to much of the region.
Rystad Energy’s senior analyst, Pratheeksha Ramdas, said in an emailed commentary:
A critical blackout lasting a few hours highlighted the heavy dependence on cross-border electricity flows.
“Spain’s high renewable penetration exposed difficulties in balancing intermittent supply, while Portugal’s complete reliance on imports underscored its lack of flexibility and energy storage.”
Just after noon on Monday, Spain’s power grid had a major hiccup, causing it to cut off entirely from the rest of Europe and plunging the country into darkness.
The Spanish mainland’s electricity transmission grid suffered a complete collapse within minutes due to intense fluctuations.
Everything went haywire when the system crashed. Metro lines in several cities went down, forcing evacuations. Airports, traffic lights, and communication networks were also affected.
Approaching the time of the power disruption, Spain’s electrical grid was experiencing demand similar to its typical midday peak.
Electricity demand was approximately 27,500 MW. This demand was primarily met through a combination of solar photovoltaic and onshore wind power, natural gas, and a small amount of nuclear energy.
Meanwhile, Portugal maintained a steady energy demand of approximately 8,000 MW, primarily sourced from hydroelectric, wind, and some imported power from Spain.
In contrast, France, benefiting from its stable nuclear-centric grid, consistently generated over 55,000 MW and continued to export excess electricity to neighboring countries.
“This regional interdependence is typically a strength — but it became a stress point in this instance,” Ramdas said.
Spain’s electricity imports
Spain typically imports a significant amount of electricity from France. However, in 2022, due to extensive nuclear maintenance in France, Spain became a net exporter of electricity for a temporary period.
Spain commonly redirects some of its imported electricity to Portugal.
This practice assists in stabilising the grids of both nations, which rely significantly on renewable energy sources.
In 2024, Spain’s electricity imports from France totaled about 10.1 GWh.
Simultaneously, its electricity exports to Portugal increased to 14 gigawatt hours (GWh).
During the power outage, French grid operator RTE’s automatic safety protocols disconnected the interconnectors.
This action isolated the Iberian Peninsula to stop the instability from extending into Central Europe, Ramdas noted.
Due to a simultaneous generation failure, Portugal experienced a sudden disconnection from external power sources, leading to an immediate energy shortage.
“Spain, likewise, lost both French imports and its own internal supply, creating a shortfall of more than 10,000 MW during the event,” Ramdas said.
France’s critical role
France played a critical role in Monday’s power crisis.
Rystad said even though France’s grid remained stable, the sudden drop in power demand from Spain and Portugal forced the country to lower power generation and re-route its energy flows.
The reported shutdown of France’s Golfech Nuclear Power Plant in the Occitanie region occurred around 12:30-12:45 p.m., coinciding with the Iberian outage.
This simultaneous event suggests a probable connection via a grid-wide frequency disturbance, according to the Norway-based energy consultancy.
Following a partial restoration of stability in Spain, France recommenced limited exports to aid in the country’s recovery.
By late afternoon, France could resume exports to Spain.
This action facilitated grid rebalancing and consequently enabled Spain to assist Portugal via secondary interconnections, according to Rystad Energy.
Power was partially restored across the Iberian Peninsula by the end of Monday.
However, a critical two–to–three–hour supply-demand gap left millions without electricity, underscoring the region’s increasing dependence on cross-border balancing.
This grid stress caused Spain’s net power exchange to shift from exporter to importer, while Portugal’s complete reliance on imported power revealed a deficit in domestic flexibility and storage.
France’s grid, stable, diversified, and somewhat insulated, showed its advantages but struggled to manage flow adjustments without prior warning, according to Rystad.
“Although France managed the situation better, it still faced difficulties in managing unexpected electricity flows,” Ramdas said.
This disruption serves as a clear warning: without stronger domestic resilience and improved regional coordination, future grid failures could have even more severe consequences.
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