# ENTSO-E final report: Iberia's 2025 blackout was triggered by over-voltage, not solar share
> Europe's worst outage in 20 years stemmed from voltage-control gaps and cascading disconnections, clearing renewables of the headline blame

**Meta:** type: story · date: 2026-05-25 · heads: O que quebrou, A mudança silenciosa · 6 takes · 3 lenses · 6 regions

## Summary

[ENTSO-E](/pt/entity/european-union) released its final report on 20 March 2026 into the 28 April 2025
[Spain](/pt/entity/spain)-[Portugal](/pt/entity/portugal) blackout, the worst in Europe in two decades, leaving 50+
million without power for up to 16 hours. The panel concluded the trigger was excessive voltage,
not a supply shortage: it was "the first known blackout caused by over-voltage." Causes interacted
, voltage oscillations, reactive-power-control gaps, divergent regulation practices between
operators, rapid output reductions and generator disconnections in Spain, and uneven
stabilisation. The findings reject the "too much solar" narrative; the report notes too few thermal
plants were online to provide voltage control, and some renewable generation tripped as the system
destabilised.

## By the numbers

- 28 April 2025, the blackout; 20 March 2026, final report release.
- 50+ million, people who lost power.
- Up to 16 hours, longest restoration time in parts of Spain (12 in Portugal).
- First, over-voltage-triggered blackout of this scale on record.

## Why it matters

The verdict reframes the policy fight: the risk in renewable-heavy grids is not generation share
but the loss of voltage and reactive-power services as synchronous thermal units retire. It pushes
operators toward grid-forming inverters, synchronous condensers and tighter cross-border voltage
coordination.

## What to watch

- Regulatory mandates for voltage/reactive-power services from inverter-based resources.
- Whether other high-renewable grids (CAISO, Australia) tighten voltage rules.
- Spanish and Portuguese operator-coordination reforms.

## Regional takes (batched by bias / lens)

### unlabelled
- **ENTSO-E** (European Union, en) — ENTSO-E expert-panel final report (released 20 March 2026) into the 28 April 2025 grid incident in Spain and Portugal.
  Source: https://www.entsoe.eu/publications/blackout/28-april-2025-iberian-blackout/
- **PV Tech** (United Kingdom, en) — 
  Source: https://www.pv-tech.org/over-voltage-triggered-iberian-blackout-report/
- **WattClarity** (Australia, en) — 
  Source: https://wattclarity.com.au/articles/2026/03/20march-finalreport-iberianblackout/
- **Wikipedia** (Global, en) — 
  Source: https://en.wikipedia.org/wiki/2025_Iberian_Peninsula_blackout

### solar-industry
- **pv magazine** (Germany, en) — Argues the report dismantles the 'too much solar' narrative, the failure was inadequate voltage and reactive-power control, with too few thermal plants providing it, not renewable penetration per se.
  > "The findings contradict claims that an over-reliance on solar power was to blame."
  Source: https://www.pv-magazine.com/2026/05/25/an-uncomfortable-truth-what-spains-blackout-really-showed/

### utility engineering
- **Power Magazine** (United States, en) — Walks through the technical chain, voltage oscillations, reactive-power gaps, divergent regulation practices and generator disconnections, framing it as a system-operations failure across operators.
  > "The first known blackout caused by excessive voltage rather than power shortages."
  Source: https://www.powermag.com/anatomy-of-a-blackout-findings-from-the-spain-portugal-grid-collapse-final-report/

## Across the graph
- Related: [[pjm-emergency-curtailment-order-2026]], [[hvdc-transmission-buildout-2026]], [[renewables-curtailment-record-2026]]
- Entities: Electricity, Spain, Portugal, European Union

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Canonical: https://rbtfl.xyz/pt/n/iberian-blackout-final-report-2026