ENTSO-E Report Finds Renewables Were Not the Cause of Iberian Blackout

Nearly a year after the Iberian Peninsula experienced one of Europe’s most serious power outages in decades, a final investigation by ENTSO-E has concluded that renewable energy was not the sole cause of the blackout. Instead, the incident resulted from a combination of technical, operational and regulatory factors that exposed weaknesses in how the electricity system manages voltage, reactive power and fast-changing grid conditions.

The blackout occurred on 28 April 2025, when the power systems of continental Spain and Portugal suffered a total outage at 12:33 CEST. A small area in southwest France was also briefly affected, while the wider European grid remained stable. ENTSO-E described the event as the most severe blackout in Europe’s power system for more than 20 years and the first of its kind in the Continental Europe Synchronous Area.

The final report was prepared by a 49-member expert panel including transmission system operators, regional coordination centres, energy regulators and ACER representatives. According to ENTSO-E, the blackout resulted from many interacting factors, including oscillations, gaps in voltage and reactive power control, differences in voltage regulation practices, rapid output reductions, generator disconnections in Spain and uneven stabilization capabilities. These factors led to rapid voltage increases and cascading generation disconnections across the affected system.

Why the Findings Matter for the Energy Transition

The conclusion is significant because the blackout quickly became part of a wider debate about whether high levels of wind and solar power make electricity systems less reliable. Spain and Portugal have both expanded renewable generation rapidly, and critics of the energy transition pointed to the outage as evidence that variable renewable energy can destabilize grids.

The ENTSO-E findings do not support that simplified explanation. The report shows that the central issue was not the presence of renewable energy, but the ability of the system to manage voltage behaviour and coordinate responses across generators, grid operators and regulators. In practical terms, this means the blackout should be understood as a grid management and system design challenge, rather than a reason to slow renewable deployment.

That distinction is important for policymakers and investors. As power systems decarbonize, they require new tools to provide services historically delivered by large fossil fuel and nuclear generators. These services include voltage support, frequency response, inertia, reactive power management and fast system monitoring. Wind, solar, batteries, synchronous condensers and grid-forming inverters can all contribute to system stability, but market rules and technical requirements must allow and require them to do so.

Voltage Control Emerges as a Central Lesson

Spain’s energy regulator, the CNMC, has also called for stronger measures to manage voltage swings after the blackout. Its recommendations include stronger power links with France, harmonized voltage rules across Spain and Europe, more rigorous inspections of protection systems and checks on installations after certification. The regulator noted that the power system is becoming more complex because of high renewable penetration, greater operational demands and increased voltage volatility.

These recommendations point to a broader lesson for Europe’s electricity market. The clean energy transition is not only about replacing fossil fuel generation with renewable capacity. It also requires investment in grid infrastructure, digital monitoring, flexible demand, storage, interconnection and ancillary services. Without these supporting systems, even a power system with abundant clean electricity can face reliability risks.

For industrial users, the findings highlight the importance of resilience planning. Companies exposed to power interruptions, including manufacturers, data centres, transport operators and telecommunications providers, may need to review backup power, demand response capability and energy management systems. The CNMC report also made recommendations for sectors affected by the outage, including railways, gas, fuel and telecommunications.

Better Regulation, not a Retreat from Renewables

The blackout also underlines the need for updated grid codes and market frameworks. If renewable plants are expected to support voltage control and grid stability, regulations must clearly define those obligations and compensate for the services when appropriate. System operators also need access to real-time data, forecasting tools and coordination mechanisms that reflect a more decentralized electricity mix.

The Guardian reported that Spain continued to expand solar capacity after the blackout, adding 13.8 GW of new solar in 2025, compared with 12.3 GW in 2024. It also reported that subsequent investigations found the lack of traditional inertia was not the decisive factor, with the final ENTSO-E report instead pointing to governance and voltage-related failures.

For Europe, the implications are wider than Spain and Portugal. Many countries are increasing renewable generation while retiring coal plants and reducing dependence on imported gas. The Iberian blackout shows that grid stability must be treated as a core part of climate and energy policy, not as a separate technical issue.

The report’s conclusions are therefore likely to shape future discussions on grid investment, interconnection, permitting, system services and electricity market design. The key takeaway is not that renewables caused the blackout, but that electricity systems must evolve faster to manage a cleaner, more dynamic and more decentralized generation mix.

Practical Implications for Businesses and Policymakers

For policymakers, the priority is to align climate targets with grid readiness. That means accelerating investment in transmission and distribution networks, strengthening cross-border interconnectors, improving voltage management rules and ensuring that all relevant technologies can provide stabilization services.

For energy companies and technology providers, the report creates a clearer business case for grid-enhancing technologies, battery storage, power electronics, advanced forecasting, synchronous condensers and grid-forming inverter solutions. For large electricity consumers, it reinforces the need to treat energy resilience as part of a net-zero strategy, rather than only as a cost or compliance issue.

The Iberian blackout was a warning about system complexity, not a verdict against renewable energy. As Europe moves toward higher shares of clean electricity, the lesson is that decarbonization and reliability must advance together.

Source: stateofgreen.com