Technical article
A Day Without Power in Portugal and Spain
If the power went out, how long would we wait?
Picture a couple named Maria and David. They are weighing a home near Lisbon against one near Valencia. Both countries share one power grid. David asks a fair question. If the power went out, how long would we wait?
The most recent large event gives us a record to read.
What happened
The European body for grid operators (ENTSO-E) says a total blackout hit continental Spain and Portugal "at 12:33 CEST" on 28 April 2025. Its expert panel published a final report on 20 March 2026. It says the cause was "a combination of many interacting factors", including voltage oscillations, weak voltage control and a chain of generators disconnecting. The pages I read give no duration.
How long it lasted
| Spain (Government report) | Portugal (energy regulator ERSE) | |
|---|---|---|
| Start | 12:33:30 | 11h33 (Portugal clock, one hour behind Spain) |
| First power back | 13:07, 31 MW | Not stated |
| Customers supplied again | Not read | 95% of consumers by midnight (ERSE presentation to Parliament, 14 January 2026) |
| About half of demand back | 22:30 or 23:32 (the report gives both) | Not stated |
| Main grid back | 99.95% of demand by 07:00 on 29 April | National grid restored about 23h20 from two hydro plants |
| Finished | 14:36 on 29 April | Not stated |
The Spanish report disagrees with itself on the half-way point. Its narrative says 22:30 and its chronology says 23:32. I show both and do not pick.
My arithmetic: in Spain, 99.95% of demand back took about 18.5 hours, and all technical work finished about 26 hours after the start. In Portugal, the main grid took about 11 hours 47 minutes to restore. That is the grid, not each home. For homes, the ERSE presentation to the Portuguese Parliament on 14 January 2026 says the distribution networks took some hours longer to restore than the transmission grid, and that at midnight 95% of consumers had supply. It puts the interruption at about 6.4 million customers and the energy not delivered at 42,135 MWh, more than six standard deviations above the average since 2009. In Portugal that is the largest outage on the regulator's record, not a typical year.
Spain's report gives demand at 12:30 as 25,184 MW, and says about 1,402.5 MW of consumer load was cut automatically at one stage. It gives no total of load lost and no cost.
Everyday outages in Portugal
The Portuguese distribution company E-REDES publishes a yearly quality report. For 2024 it states "um TIEPI MT de 49,5 minutos" for the country (equivalent interruption time in medium voltage, per the tool summary). By zone, it lists 32.26 minutes for zone A, 48.03 for zone B and 60.12 for zone C (accidental interruptions). Zone A is the densest. The report does not show a publication date. https://www.e-redes.pt/sites/eredes/files/2025-05/Relat%C3%B3rio%20da%20Qualidade%20de%20Servi%C3%A7o%202024.pdf
What this article leaves for another day
- What the outage cost either country. Neither regulator has published a figure; compensation questions sit with the courts and the regulator's rules on exceptional events.
- How often outages occur in Spain. The ministry points to an online tool for the yearly figures.
- Official advice on keeping a home running for a day. The tips in the list below are mine.
You could…
- Ask the grid operators (Red Eléctrica in Spain, REN in Portugal) for yearly outage records for your street.
- Ask a building owner whether the lift and water pump have backup power.
- Read the ENTSO-E final report for the technical detail.
If the power went out at lunch tomorrow, what would you most want to have in the house?
Figures are estimates for planning, based on public data. Date read: 10 and 11 October 2026.
Tell us in the comments