Lessons from the Iberian Peninsula Blackout

At 12:33 p.m. local time on Monday, April 28th, 2025, the Iberian Peninsula experienced its most significant power outage in history. Within minutes, tens of millions of people across Spain, Portugal, and parts of Southern France lost electricity for most of the day.

Since SEPA last published a blog about the Iberian Peninsula power outage, experts have gained a deeper understanding of the precise events that occurred on April 28th. Following the blackout, the Spanish government immediately began working to identify the causes; this June, Red Eléctrica, Spain’s transmission system operator, released a report analyzing the events that led to the blackout, and Spain’s Ministry for Ecological Transition published a detailed analysis.

Not a Cyberattack or a Failure of Renewables

Part of the Ministry’s task was to rule out any possibility of a cyberattack. A Ministry committee analyzed over 300 GB of information and conducted the most extensive cybersecurity investigation in Spain’s history to date. Following this investigation, the Ministry ruled out a cyberattack at the control centers, the system operator facilities, or any of the involved generation facilities.

Additionally, because Spain is a European leader in renewable energy (renewables contributed 56% of Spain’s electricity mix in 2024), government officials also explored whether the intermittency of renewables might have caused instability. The government’s report made it clear that renewables were not the cause of the April 28 blackout.

The Chain Reaction Behind the Blackout – And Steps to Prevent Future Blackouts

The story of what caused the blackout was far more complicated, as a chain reaction, rather than one single isolated event, led to the outage. As a Grid Strategies report explains, inadequate voltage control was a central factor behind the blackout. Rising voltage contributed to a chain reaction that led to disconnections at generating facilities in provinces throughout Spain. This series of events ultimately severed the interconnection between Spain and the rest of the continent. In other words, the loss of voltage control, compounded by low system inertia, triggered the protective actions of the electric current, which can be viewed as a circuit breaker tripping on a continent-wide scale.

Source: NERC Presentation

What Policy Changes are Spanish and Portuguese Authorities Implementing?

• Policy reforms: In June 2025, Spain approved legislation focusing on energy storage, grid reinforcement, and improved system operation. However, it was blocked by the Spanish Parliament in July 2025; legislative revisions are pending.
• Grid investments: Portugal announced a €400 million investment package for its grid, including increasing grid battery power to 750 MW and enhancing resilience for critical facilities.
• Increased interconnection: The Iberian Peninsula is isolated from the European grid compared to many other nations, which compounded the events of April 28th. New interconnection projects are underway, such as the “Bay of Biscay” interconnect between Spain and France, which would facilitate increased voltage frequency regulation, grid capacity, and reliability.

What Lessons Can We Apply to the U.S. Grid?

During a June presentation to FERC, Mark Lauby, the Senior Vice President and Chief Engineer at the North American Reliability Corporation (NERC), reviewed Spanish authority reports about the blackout and discussed implications for the U.S. grid. NERC determined that many of the concerns identified in the Iberian blackout have been addressed in North America with existing NERC Reliability Standards.

In a recent conversation with SEPA, Mark noted:

These findings are reassuring regarding North American grid reliability; nevertheless, as we look back on the April 28th event, the disruption and resulting international attention serve as a reminder of the vital importance of planning for the most resilient grid possible. Investing in reliability improvements such as replacing poles and wires, upgrading substations, managing system voltage with synchronous condensers and bulk electric storage systems, and improving redundancy can all make the U.S. grid more resilient. Emerging technologies, including virtual power plants (VPPs), grid-forming and power oscillation damping inverters, microgrids, and distributed energy resource management systems (DERMS), can also improve flexibility and reliability.

Wildfire Resilience as a Grid Imperative

This summer, Spain experienced its hottest summer on record. The month-long heatwave contributed to deadly wildfires, which burned roughly one percent of the total land area of the Iberian Peninsula, and contributed to the worst European wildfire season since records began in 2006. Extreme heat can cause power lines to sag and expand and transformers to overheat, leading to heightened fire risk, while increased strain on the electric grid due to increased air conditioning use can also contribute.

Utilities in the fire-prone regions of the United States are experiencing similar contributing factors to increased wildfire risk on the grid. Changing weather and climate patterns, coupled with rapid urbanization, have increased the exposure of utility assets to fire hazards. U.S. investor-owned utilities’ capital expenditures grew from $136.6 billion in 2021 to a projected $167.8 billion in 2023, with an average of 36% directed toward adaptation, hardening, and resilience. Furthermore, twenty major utilities—including PG&E, SCE, Xcel Energy, PacifiCorp, APS, and others—have committed over $21 billion in wildfire mitigation investments through 2027.

Utilities nationwide are also implementing wildfire mitigation plans (WMPs). As of July 2025, nine states have passed legislative mandates requiring wildfire mitigation plans, with other legislation pending. For example, California investor-owned utilities (IOUs) operate under mandatory three-year WMPs, while other states have implemented varying requirements from voluntary planning to emerging statutory mandates. In addition to infrastructure investment and wildfire mitigation plans, utilities are also implementing preventative public safety power shutoffs (PSPS) to prevent utility-sparked wildfires during extreme fire weather conditions. PSPS events are a last-resort measure that utilities may use to prevent utility-ignited fires.

SEPA’s recent Wildfire Mitigation Webinar Series provided practical insights into wildfire risk assessment, mitigation planning, and the latest technologies available to strengthen grid resilience. Drawing on the experiences of SEPA members, industry leaders, and wildfire resilience experts, the five-part series highlighted real-world strategies that utilities of all sizes, in all countries, can implement.

See SEPA’s resources on grid resilience:

• Resilient by Design: Utility Strategies for Climate-Ready Distribution Systems
• Decoding DERMS: Options for the Future of DER Management
• 50 States of Virtual Power Plants and Supporting Distributed Energy Resources: 2024 State Policy Snapshot and Q2 2025 updates.
• SEPA and NRECA Resilience Planning Playbook for Electric Cooperative Utilities

Next Steps: Planning for a More Resilient Future

The Iberian Peninsula blackout and the wildfires this summer are part of the emerging global dialogue on grid resilience and wildfire mitigation. As the U.S. faces rising load growth and intensifying extreme weather events, SEPA continues to partner with experts both internationally and domestically to share the latest information and best practices on grid resilience. For SEPA members, join SEPA’s Resilience Working Group for new connections and in-depth peer-to-peer information sharing.

Stay tuned for findings from our 2025 Executive Fact Finding Mission to Portugal (October 26-31).

Questions? For SEPA members, email our complimentary member research service, staffed by SEPA experts: [email protected]