Understanding the April 2025 Spain Blackout: A Translation of Red Eléctrica de España’s Briefing
A system-wide collapse, two triggering events, and a coordinated restart—what Spain’s system operator has confirmed so far.
On Sunday 28 April 2025, Spain experienced a rare system-wide blackout. In a live press conference titled “DIRECTO APAGÓN | Red Eléctrica descarta de forma preliminar un incidente de ciberseguridad” (“LIVE BLACKOUT | Red Eléctrica preliminarily rules out a cybersecurity incident”), Red Eléctrica de España (REE)—the national electricity system operator—shared early findings on the causes, system response, and restoration efforts.
This summary draws together the main insights from the briefing and reflects on the technical, operational, and structural considerations emerging from the incident.
A related earlier piece, Spain and Portugal’s Five Seconds of Instability, explores earlier parallels with events like South Australia’s 2016 blackout and highlights the recurring importance of system strength, validated generator models, and operational readiness in a high-renewables grid.
REE’s Role in the System
Red Eléctrica de España (REE) operates the high-voltage transmission network and oversees the secure and continuous functioning of Spain’s electricity system. It coordinates supply and demand in real time and leads restoration when disruptions occur. During major incidents such as this, REE serves as both system coordinator and national communicator.
The organisation’s central position within the grid made it the key source of information and response as the blackout unfolded.
This summary is based on a ChatGPT-assisted English translation of the official YouTube Live press conference transcript by Red Eléctrica de España. While best efforts have been made to convey the meaning faithfully, readers should refer to official sources or request confirmation from REE for critical details or formal use.
What Happened: A Collapse in Seconds
At 12:33 pm, the system was operating normally. Power flows, frequency, and voltage remained stable. Within a five-second window, a chain of events altered that status dramatically:
A first event, interpreted as a loss of generation in the southwest, where solar generation is prevalent
A second, shortly after, which degraded system stability further
A resulting cascade of effects, including:
Disconnection of significant volumes of renewable generation
Separation from the interconnection with France
Widespread load-shedding
A complete voltage collapse across the Iberian Peninsula
This was the first nationwide blackout of this scale in at least five decades.
No Cyberattack, No External Interference
The speed and scale of the event raised concerns about the possibility of a cyberattack. REE confirmed it worked with Spain’s national cybersecurity and intelligence bodies (CNPIC, CCN, and CNI), all of whom ruled out malicious activity.
No evidence was found of:
Intrusions into REE’s systems
External commands being issued to generators
Breaches of cybersecurity protocols
The incident was physical in nature, with all signs pointing to cascading failures among grid-connected assets.
Restoration Strategy and Execution
Restoration was coordinated using established emergency protocols. The process began by drawing power from interconnections with France and Morocco to energise:
The Basque Country
Catalonia
Southern Andalusia
This enabled auxiliary systems in power stations to restart. Hydroelectric plants, especially those with autonomous start capability, played a key role. So too did combined-cycle gas turbines.
By 4:00 am, all transmission substations had been re-energised. By 7:30 am, approximately 99% of expected demand had been restored. Some consumers experienced longer outages due to local distribution-level issues.
Investigation and Known Unknowns
REE outlined what has been confirmed and what remains under review.
Confirmed so far:
The sequence began with the loss of generation in the southwest
System frequency and voltage declined rapidly
Large volumes of renewable generation disconnected as protection systems activated
The grid was unable to withstand the combined disturbance
Still being investigated:
The precise location, size, and cause of the initial disconnections
Whether protection schemes triggered too early or failed to ride through
The role of telemetry and data systems, some of which were frozen at pre-event levels
Full data from generation control centres is still being compiled. REE has urged restraint in speculation until that analysis is complete.
Observations on System Flexibility
The blackout occurred in a system undergoing rapid decarbonisation. The high share of inverter-based renewables, lower system inertia, and limited interconnection with neighbouring grids all contributed to the severity of the event.
A few key factors stood out:
Hydro and gas proved critical for restoration
Interconnection limitations with France added to system fragility
Storage was not yet available at the required scale to support system resilience
Self-consumption systems, such as rooftop solar, require enhanced observability to ensure coordinated operation
REE noted that greater visibility into distributed energy resources is becoming essential, and it is working on a representative panel of self-consumption via IoT to improve situational awareness.
Looking Ahead
Work is underway to:
Finalise the technical root cause analysis
Update and refine operational protocols
Implement additional safeguarding measures across the system
The Gulf of Biscay interconnection, currently under construction, is expected to improve system robustness. REE also reaffirmed the importance of scaling up storage and flexibility services, alongside a deeper digital integration of distributed energy.
Closing Reflection
While rare, the blackout has highlighted systemic stress points in an evolving grid. Restoration was swift, and communication transparent, but the event marks a turning point in how resilience must be framed: not just as an emergency response capability, but as a design priority for systems increasingly shaped by variable, distributed, and weather-dependent resources.