How the Lights Went Out in Spain

The country flew too close to the sun—which is to say it relied too heavily on unreliable solar power

By Gabriel Calzada and Manuel Fernández Ordóñez. Messrs. Calzada and Fernández Ordóñez are senior fellows at the University of the Hesperides’ Peter Huber Center. Excerpts:

"days before, Spain’s government had announced that its grid had for the first time run entirely on renewable power, with new records set almost daily for solar."

"By Tuesday Socialist President Pedro Sánchez was blaming private industry."

"any reliable grid system must be designed with such events in mind"

"The greater the share of renewables vis-à-vis conventional power plants with synchronous turbines, the less inertia there is to cushion instantaneous load fluctuations in the grid. The system becomes increasingly fragile, with higher risk of failure." 

"At the time of the disaster, Spain’s near-record percentage of solar-energy production was accompanied by a smaller amount of wind—neither of which are capable of stabilizing the system if needed. The grid was also running with a low share of turbine-based generation—around 30%."

"A combination of low market prices and a high punitive tax burden—accounting for 75% of the variable cost of energy production—also left half of the country’s nuclear capacity out of the game."

"grid was operating with very little margin for error" 

"Between April 2024 and April 2025, the most relevant synchronous generation sources—nuclear, combined cycle and hydroelectric—fell from an average of 30.5% to 23%."

"state-controlled company that manages the grid forcefully denied the possibility of blackouts."