ERSE Classes the 28 April 2025 Iberian Blackout as an 'Evento Excecional' and Strips Portuguese Consumers of Automatic Compensation From REN and E-Redes — Three-Year Judicial-Damages Window in Lisbon and Madrid Stays Open

The Entidade Reguladora dos Serviços Energéticos (ERSE) issued its formal ruling on the 28 April 2025 Iberian blackout on Tuesday 26 May, classifying the event as an evento excecional under the regulator's quality-of-service framework for the electricity and natural-gas sectors. The legal consequence is direct: REN, the national transmission operator, and E-Redes, the EDP-owned distributor that runs the low-voltage network reaching households and small businesses, are exempted from paying the individual quality-of-service compensations that would otherwise be deducted from operator revenues and credited to consumer bills the following year. The decision answers a joint exemption request the two operators filed with ERSE in the months after the outage, and forecloses the automatic-compensation route that Portuguese consumer associations had been counting on through the post-blackout recovery file.

The regulator framed the call on two grounds. The first is the extraordinary nature of the collapse — ERSE noted there is no comparable Iberian incident in sixteen years of grid records to set against the April 2025 cascade, which took the entire Portuguese transmission system off the grid for hours and forced a black-start sequence run by REN with European operator support. The second is the causality finding: the trigger was located on the Spanish side, in events not attributable to the affected Portuguese network operator. With those two boxes ticked under the quality-of-service regulation, the evento excecional label exempts the operator from penalty calculations regardless of the duration or frequency thresholds that would normally fire compensation payments.

What the Compensation Regime Normally Does

The standard ERSE regime keeps a running file on each customer connection — the number of interruptions, the duration of each interruption, and whether the cumulative reading crosses the regulatory thresholds for the relevant voltage level. When a customer's record breaches the threshold and the responsibility sits with the operator, the regulator's machinery automatically calculates a compensation amount, the operator carries the deduction off its allowed revenue, and the credit appears on the next annual billing cycle as a one-line adjustment. For a household on the low-voltage network, the per-event credit is modest; for a continuous-process industrial customer on medium- or high-voltage supply, a single thresholded outage can run into tens of thousands of euros. The aggregate annual compensations across the network are tracked in ERSE's Relatório da Qualidade de Serviço and have run in the low single-digit millions of euros in recent normal years.

The 28 April 2025 outage broke every record on every metric the regime measures. Had ERSE classified it as a standard operator-fault interruption, the aggregate automatic compensation across the Portuguese consumer base would have run into a multiple-of-annual-baseline number — a transfer that, in the regulatory accounting, would ultimately have hit the regulated revenue floor REN and E-Redes are entitled to collect across the next tariff cycle. The evento excecional ruling short-circuits that calculation entirely.

What Consumers Keep

The ERSE decision explicitly leaves the judicial-damages route open. Consumers who can document a concrete loss — spoiled stock at a restaurant or cold-chain operator, lost production hours at an industrial customer, equipment damaged at the moment of supply restoration — retain the right to pursue civil-liability claims against whichever entity is identified as responsible for the cascade. The statute of limitations runs three years from the date the injured party became aware of the damage and of the responsible party, and the venue can be either Portuguese or Spanish, depending on the configuration of the claim and the corporate identity of the targeted defendant. Where the trigger event is located in Spain, the claim will, in practice, often have to be filed in Spanish administrative or civil courts, with the procedural and language costs that implies.

The Portuguese consumer associations — DECO PROteste chief among them — have signalled they will explore collective-action routes rather than push individual claims through the courts. The associations' working assumption through the summer was that ERSE would land on this side of the line; the formal ruling now removes the ambiguity and starts the political timeline on a legislative or regulatory amendment that would carve out a specific compensation track for system-wide events. That is a Parliament-led conversation rather than an ERSE-led one.

The Operator Side

REN and E-Redes both treated the exemption request as core to their post-event accounting. The 28 April collapse landed inside the Período de Regulação currently in force, and both operators have to demonstrate to the regulator that their cost-of-service base — and the allowed return on the regulated asset base — does not absorb event-level shocks for which the cause originated outside their perimeter. The ruling, on that level, is the operational answer ERSE owed both companies: the cost of the 28 April cascade does not unwind into the regulated-revenue allowance for the remainder of the period.

The other side of the operator file is the preparedness measures the Banco de Portugal, the government's blackout working group and the parliamentary inquiry have been negotiating since the second half of 2025. The national payment-resilience plan the central bank stood up earlier this month, the 72-hour backup-power recommendation from the parliamentary inquiry, and the €4 billion grid-rewiring envelope the government unveiled at the one-year mark all sit upstream of the ERSE decision. None of those plans depended on the compensation question, but the ERSE ruling concentrates the political attention on the preparedness lane: with no compensation to collect, the file that matters to consumers is the next-time question, not the last-time question.

The Cross-Border Geometry

The Iberian electricity market is a single market — MIBEL — but the regulatory and liability frameworks are still national. ERSE rules the Portuguese operators; the Comisión Nacional de los Mercados y la Competencia (CNMC) rules their Spanish counterparts. Both regulators have to land on a causality reading before either can finalise its quality-of-service treatment, and both have to navigate the European Network of Transmission System Operators (ENTSO-E) post-event report. ERSE's decision tracks the technical reports that have circulated through ENTSO-E and the joint REN–Red Eléctrica de España working group: the trigger sits on the Spanish side, the cascade propagated through the interconnection capacity, and the Portuguese system experienced a system-wide collapse that was — within the regulatory framework — not of its own making.

For the cross-border judicial route, the consequence is operational. A Portuguese restaurant that lost a freezer-load of stock will, in practice, be filing against an entity whose legal seat is in Madrid, in a Spanish court, with a Spanish-language file. That bar is high enough that most household-scale claims will not clear it. The medium- and large-scale industrial customers carrying line-item losses in the hundreds of thousands or millions of euros will. The three-year clock is running.

What This Means for Expats

• No automatic credit on your 2026 electricity bill. If you were waiting for a line-item refund tied to the 28 April 2025 outage, ERSE has confirmed it is not coming. Operators will not deduct compensation amounts from the allowed revenue this cycle.
• The judicial route remains open if you took a concrete loss. Documented damage — spoiled stock, ruined equipment, lost production hours — can be claimed for three years from the date of awareness. The likely venue, where Spain is identified as the trigger jurisdiction, is a Spanish court.
• Collective action is the realistic route for households. Individual claims for €40 of spoiled food will not justify cross-border litigation. Consumer associations will be the channel that aggregates the small claims if they can secure the procedural fit.
• Insurance is your other lane. If your home or business insurance carries a power-loss or business-interruption rider, the policy terms — not the ERSE ruling — define your recovery. Some policies exclude wide-area outages; some do not.
• Watch the preparedness track. The compensation question is now closed. The hardening-the-grid file, the 72-hour backup-power push and the Banco de Portugal payment-resilience plan are the live policy lanes — and the ones that will define how a future event is handled.

Sources: ERSE, deliberação on the REN and E-Redes joint request for evento-excecional classification, 26 May 2026; ECO and Jornal de Negócios reporting on the ruling; regulamento da qualidade de serviço dos setores elétrico e do gás natural; Banco de Portugal Relatório dos Sistemas de Pagamento, May 2026.