Spanish Grid Collapse Places Spotlight On Grid Resilience, Diversified Sourcing

With power restored to over 99% of consumers by 29th April, the power outage in Spain and Portugal that happened on the 28th is the subject of deep investigation. Depending on which side of the fence you are, people have rushed to blame/defend renewable energy, but a more clear eyed certainty seems to be anything but. The only factor going against renewables is the possible inability or tolerance of the grid to frequency disturbance at the moment event unfolded.

Here is what  senior analyst Pratheeksha Ramdas at Rystad Energy had to say about it –“The partial restoration of power across Iberia has brought to light a deeper vulnerability in the region’s energy system. 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. Although France managed the situation better, it still faced difficulties in managing unexpected electricity flows. This disruption serves as a clear warning: without stronger domestic resilience and improved regional coordination, future grid failures could have even more severe consequences.”

Cause Unknown, Yet
Spain’s national grid operator, Red Electrica (REE), and Portugal’s E-Redes are investigating the exact causes that led to abnormal oscillations in the high-voltage lines and synchronization failures across the interconnected power grid into France.

As power has now returned to large parts of the region, the generation mix in each country played a significant role in both the failure and the recovery, preliminary Rystad Energy analysis shows.

The blackout began with a sharp fluctuation in the Spanish electricity grid, which caused the entire electricity system to disconnect from the rest of the European system at around 12:30 p.m. on Monday.

Within minutes, the intense fluctuations led to a complete collapse of the Spanish mainland’s electricity transmission grid.

The failure had an immediate impact on everyday life, with metro systems grounding to a halt across multiple cities, forcing emergency evacuations of underground transport, while airports, traffic signals, and communications networks ceased functioning.

In the hours leading up to the outage, Spain’s electricity system was operating near midday peak levels.

Demand hovered around 27,500 megawatts (MW), largely supplied by a mix of solar PV and onshore wind, natural gas, and some residual nuclear generation.

Portugal was managing steady demand at around 8,000 MW, largely reliant on hydro, wind, and some imported electricity from Spain. Meanwhile, France, with its stable nuclear-heavy grid, maintained output above 55,000 MW and continued to export surplus electricity across its borders.

This regional interdependence is typically a strength — but it became a stress point in this instance.

Cross Border Electricity Flows a Key Factor

Spain has traditionally relied heavily on electricity imports from France, with the notable exception of 2022 when extensive nuclear maintenance in France temporarily turned Spain into a net exporter.

Typically, Spain also transfers a portion of the imported power to Portugal to help balance the renewable-heavy grids of both countries.

In 2024, Spain imported approximately 10.1 GWh from France, while its exports to Portugal rose to 14 GWh.

During the outage, France’s grid operator RTE activated automated safety mechanisms that severed the interconnectors, isolating the Iberian Peninsula to prevent the instability from spreading into Central Europe. As a result, Portugal was suddenly cut off from external power at a time of generation failure, forcing it into an immediate energy deficit.

Spain, likewise, lost both French imports and its own internal supply, creating a shortfall of more than 10,000 MW during the event.

France’s role in the crisis was critical.

Although its grid remained stable, the sudden drop in Iberian demand forced the country to temporarily reduce generation output and re-route its energy flows.

Notably, the Golfech Nuclear Power Plant in the Occitanie region of France was reportedly forced to shut down around 12:30 -12.45 p.m. — the same time the Iberian outage occurred — indicating a likely link through grid-wide frequency disturbance.

Once stability was partially restored in Spain, France resumed limited exports to assist with recovery.

By late afternoon, France was ready to export back into Spain, helping to jumpstart grid rebalancing and allowing Spain to support Portugal through secondary interconnection lines.

The generation mix in each country played a significant role.

Portugal’s renewable generation was hit the hardest, with wind output collapsing by more than 54% during the outage.

High solar generation also contributed to initial grid fluctuations, as solar accounted for around 29% of Spain’s total generation at the time of the event, making the system more sensitive to voltage instability.

France’s nuclear fleet, however, provided steady baseload generation throughout the event, giving it the ability to respond swiftly once interconnectors were re-engaged.

By the end of yesterday, power was partially restored across the Iberian Peninsula. However, the supply-demand gap during the critical 2–3 hour window left millions without electricity and highlighted how dependent the region has become on cross-border balancing.

Spain’s net power exchange flipped from exporter to importer, while Portugal’s complete reliance on imported power during grid stress exposed a lack of domestic flexibility and storage. France, meanwhile, demonstrated the benefits of a stable, diversified and partially insulated grid but also faced the challenge of adjusting flows without advance notice.