One year on from the large-scale blackout of 28 April 2025, the Unión Española Fotovoltaica (UNEF) judges the Spanish power grid to be in a more stable condition than before the incident. Among the reasons it cites are new rules allowing renewable energies to participate in voltage control, alongside the continuing expansion of storage capacity.
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According to UNEF, several technical reports – including those by ENTSO-E, the Spanish Ministry for the Ecological Transition (MITECO), grid operator Redeia and Comillas University – conclude that the blackout was not triggered by a shortfall in rotational inertia, but by problems in the voltage control mechanism. Renewable installations would have been technically capable of providing the service, but were not permitted to do so at the time, owing to the outdated operating rule PO 7.4.
Regulatory progress – but work remains to be done
Among the welcome developments, UNEF cites the update to rule to PO 7.4, which allows photovoltaic and other renewable installations to participate in voltage control. However, the association demands that in future not only plants connected to the transmission grid, but also those connected to the distribution grid should be allowed to provide this service. UNEF is also calling for the introduction of a regulatory framework for so-called grid forming, so that renewable installations can also provide inertia services.
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Application of the technology now depends only on the technical implementation criteria set by ENTSO-E. "The blackout has shown that regulation must not lag behind technology. Had certain measures, such as voltage control by renewables and appropriate regulation for storage, been adopted when the sector first called for them, the incident could probably have been avoided," says UNEF Director General José Donoso.
Remuneration gap holds back PV in voltage control
According to UNEF, 4.5 GW of renewable capacity currently takes part in voltage control, against an estimated potential of 32.5 GW. The low level of remuneration is acting as a brake: renewable installations currently receive 1 euro per MVArh, whereas combined-cycle gas plants receive between 100 and 200 euros per MVArh for the same service. The present rate does not even cover the minimum investment needed for software updates, the recalibration of components or the plants' own electricity consumption.
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UNEF puts the cost of technical restrictions for voltage control at 2.303 billion euros in 2025, of which 725 million euros went on so-called reinforced operational management. With greater participation by renewables, Donoso says, "90 percent of these total costs could be saved."
Renewables push down electricity prices
UNEF also points to the price-dampening effect of renewable energies. "With the impact of the conflict in the Middle East, we are seeing how the electricity price in Spain has been three to five times lower than in Germany and seven times lower than in Italy, because renewables protect us, especially during the hours of sunshine," says Donoso.
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The association is therefore appealing to policymakers and institutions to ensure regulatory stability and to drive forward the electrification of households and industry. UNEF also welcomes recent progress on storage expansion, while warning of bottlenecks in permitting procedures caused by understaffing in public administration. (nhp)
