ENTSO-E: the major Iberian blackout of 28/04 was not due to renewables, but to overvoltage
Summary: The ENTSO-E factual report on the blackout of April 28, 2025 in Spain and Portugal concludes that the cause was an overvoltage and lack of voltage control, ruling out an excess of renewables. Spain has already updated PO 7.4 to allow renewable generation to provide voltage services. Sources.
What happened and why it matters
The ENTSO-E expert panel published a factual report that reconstructs system conditions, sequence of events, and service restoration. It does not assign final blame (that will come with the full report in 2026), but it does highlight that the event was exceptional due to overvoltage and a lack of control resources connected at that time.[1]
Technical keys in plain language
- Overvoltage: grid voltage rose above safe margins, triggering protections and cascading disconnections.
- Control resources: there were few “synchronous” generators and online voltage support services; part of the renewable generation disconnected as the system destabilized.[1]
- Renewables not to blame: solar/wind production was normal for the season; the issue was control/planning, not “too much PV”.[1][2]
What changes after PO 7.4 (12/06/2025)
Spain enables renewables and storage to participate in voltage control services. A rollout of inverters with grid-forming functions and more batteries is expected to provide grid support, along with new technical obligations for self-consumption plants and PPAs.[3]
What it means for your projects (residential, industrial, agricultural)
- Size storage with grid services in mind (potential future revenues).
- Choose inverters compatible with voltage support (advanced functions, ride-through, Q/U control).
- Review protections and voltage disconnection curves to meet updated requirements.
- In PPAs and industrial self-consumption, plan for voltage control capability in detailed engineering.
Aurensol recommendations
- 48 V lithium batteries for flexibility and grid support.
- Three-phase hybrid inverters with advanced functions.
- All-in-one systems for turnkey projects.
- DC protections and AC as appropriate.
Sources and context
- PV Tech: “Over-voltage triggered Iberian blackout – report” (06/10/2025).
- Official statements and international coverage ruling out cyberattack and excess renewables.
- Update of PO 7.4 in Spain (12/06/2025): renewables can provide voltage services.
Aurensol will closely monitor the publication of the full ENTSO-E report in 2026.
