Fact VS Fiction: Did Renewable Energy Cause the Spain Power Outage?

On April 28, 2025, the power went out across all of Spain and Portugal, bringing daily life to a halt for 10 hours. Chaos ensued and Spain called a national emergency.  What caused this? Once a cyberattack was ruled out, many sources were quick to blame renewables for the outage. On April 16, 2025, Spain made headlines for achieving 100% renewable energy on a weekday for the first time. And yet, twelve days later, when renewables were providing 60% of their electricity, the grid went dark. Are the two linked? Let’s dive in and clear things up.

Failure to Adequately Control Voltage Cause a Chain Reaction

In June of 2025, the Spanish government and the Spanish grid operator Red Electrica each released lengthy reports on the cause of the outage. The reports found that the Spanish grid operator currently only allows conventional power plants (i.e. coal, gas, nuclear and hydro plants) to provide voltage control, and those conventional power plants failed to respond to voltage oscillations to maintain voltage on the electricity system. Grid Strategies reviewed the June reports, which concluded:

“The ultimate cause of the peninsular electricity blackout on April 28 was a phenomenon of overvoltages in the form of a “chain reaction” in which high voltages cause generation disconnections, which in turn cause further increases in voltage and with it new disconnections, and so on. This phenomenon was preceded by high-amplitude voltage variations in short periods of time throughout the morning.” 

To put this into simpler terms: the high voltage caused some transformers to disconnect power plants, which then made the voltage go even higher, causing more disconnections, and the cycle kept repeating. Eventually, the voltage got so high that, to protect the grid, the electricity system collapsed and caused a widespread blackout.

Renewable Energy Can Actually Help Regulate Voltage

Inverter based resources (IBRs) (i.e., wind and solar, especially when paired with batteries) can regulate voltage very quickly, if they are allowed to do so. In this case, the Spanish grid only allowed conventional generators to control voltage, which contributed to this voltage chain reaction. The investigators conclude that allowing renewables and batteries to regulate voltage could have prevented this outage. Notably, “Spain’s practice differs from requirements in the U.S., where for nearly a decade FERC Order 827 has required newly installed IBRs to regulate voltage.”

Renewables Make for a Resilient and Reliable Energy Grid

Given the widespread availability and affordability of wind, solar and battery storage, and since these resources contribute to grid reliability, the grid has the potential to be more resilient and reliable than ever. This is the case in many parts of the world where grid operating procedures utilize renewable and battery resources to regulate grid voltage and stabilize grid irregularities. Prioritizing and standardizing this practice (as is being done in the United States) contributes to highly reliable electricity grids even with 70% or more of renewable penetration to the grid. This is increasingly evident as we see regular headlines that entire regions have been powered by a majority of renewables for significant periods.