Just because Spain went black is no reason to pan solar power!

Listen, to have all the power go out every so often is a small price to pay to be able to say you're environmentally friendly. Unless you're having surgery...then it's a fairly significant inconvenience. But honestly, there are plenty of other place you can go for medical care.

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, WSJ

Updated April 30, 2025 4:01 pm ET

A solar power plant in Caudete, Albacete, Spain, April 30. Photo: eva manez/Reuters

Canary Islands, Spain

Life changed for Spaniards at noon on Monday. With the sun at its peak, the country’s largely solar-powered electrical grid shut down. Mere 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. Breathless declarations of victory flowed, in service of the government’s promise to phase out reliable nuclear power plants with many years of remaining service life. As in Germany, this promise is now the Spanish politicians’ nightmare.

In only a few minutes, Spain and Portugal (whose grid and energy policies are interconnected) went dark, along with parts of France. The Spanish government discovered modesty, but only temporarily. By Tuesday Socialist President Pedro Sánchez was blaming private industry. With havoc in the cities and trains stuck in the countryside, he held a press conference to address what he acknowledged was an unprecedented disaster. With half the country still without access to electricity, Mr. Sánchez asked Spaniards to limit use of cars and cellphones as the government investigated.

While the discrete triggering event isn’t yet known, any reliable grid system must be designed with such events in mind, be they meteorological or technical. The stability of an electrical grid depends on a balance maintained through synchronous generation using turbines that store energy in their rotating generators. These generators provide inertia that can stabilize the grid if the network load exceeds the capacity of connected power plants—or in the opposite case, if there’s excess generation.

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%. Low inertia meant playing with fire (or, more accurately, with the sun, given that Spain’s policymakers minimized thermal generation).

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. This meant that Spain’s electrical grid was operating with very little margin for error, a risky game that the Spanish government has been playing more aggressively each year since energy-transitionist ideologues took power two decades ago.

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%. The few voices that warned of the considerable risk of forcing in too much renewable power were marginalized by the system operator. This state-controlled company that manages the grid forcefully denied the possibility of blackouts. Media outlets supportive of the government amplified these denials.

A modern society can’t function without an electricity grid. By continuously reducing inertia, Spain’s policymakers engineered a vulnerability. The grid collapse was the result of a series of brazen missteps by lawmakers. They disregarded warnings grounded in laws of physics. One could say that Spain flew too close to the sun, leaving its electrical grid exposed to imbalances that became impossible to stabilize.

Events will inevitably test any electrical system’s limits. A rational system should be designed to handle such events. Spain’s system was engineered politically, not rationally. It’s the latest lesson in how not to make energy policy. Will anyone learn from it?

Messrs. Calzada and Fernández Ordóñez are senior fellows at the University of the Hesperides’ Peter Huber Center. Daniel Fernández contributed to this article.