Yesterday’s widespread Spain-Portugal power outage has generated multiple theories, ranging from plausible grid failures to the curious ‘rare atmospheric phenomenon’ explanation from Portuguese grid operator Ren.
While investigations continue, our early technical observations point to a cascading grid failure exacerbated by high solar PV penetration and insufficient system inertia.
Let’s consider the competing theories—and why most don’t hold up.
What could have caused the Spain-Portugal power blackout?
1. Grid instability due to high renewable use (most likely)
What happened? A transmission line fault (e.g., insulation failure) triggered a cascade:
- Solar PV inverters tripped due to lack of fault ride-through capability.
- The sudden loss of generation overloaded remaining plants, collapsing the grid.
Why it fits? Matches known challenges in high-renewable grids: low inertia, inverter sensitivity.
2. Geomagnetic phenomenon (unlikely)
Claim: Solar storms or geomagnetically induced currents (GICs) disrupted the grid, overheating transformers or causing protection systems to trip.
Reality:
- No solar storm activity: Space weather monitors reported quiet geomagnetic conditions (Kp index < 2), ruling out solar-induced GICs.
- GICs vs. inverter tripping: GICs cause quasi-DC currents in transformers, leading to saturation, harmonics, and thermal stress—but these develop over minutes to hours, not the sub-second collapses seen here.
- Transformer damage unlikely: Severe GIC events (e.g., 2003 Sweden blackout) typically require strong, sustained storms—none were present.
- Inverter behaviour unexplained: GICs don’t directly trip solar PV inverters; the blackout’s instantaneous cascade points to a fault-driven inertia crisis, not space weather.
3. Cloud cover & wind drop-off (plausible, likely not the root cause)
Claim: A sudden loss of solar/wind generation due to weather caused a frequency drop.
Reality: While clouds or calm winds can reduce renewables output, grids are designed to handle such variability. The speed of collapse suggests a fault, not gradual generation loss.
4. Atmospheric phenomenon (unsupported)
Claim: Rare atmospheric conditions induced harmonics or voltage swings.
Reality: No extreme weather or documented atmospheric interference occurred. Harmonics stem from grid equipment, not the atmosphere.
5. Sabotage or cyberattack (no evidence yet)
Claim: Malicious actors disrupted the grid.
Reality: No signs of hacking or physical attacks. The Spain-Portugal power outage failure pattern aligns with natural grid dynamics.
Why the Spain-Portugal grid instability theory wins
- Inverter behaviour: Solar PV’s abrupt disconnection points to lack of grid-forming capabilities.
- Cascading failure: The blackout’s progression (auto-reclose attempts, then full collapse) mirrors classic inertia-driven collapses.
- Precedent: Similar events (e.g., South Australia 2016) were caused by renewables tripping during faults.
Preventing future blackouts
- Update grid standards: Require inverters to provide synthetic inertia and stay online during faults.
- Model disaster scenarios and build recovery plans: NESO has already suggested this, from the initial response to what recently happened at Heathrow (the full report into what happened is imminent). Fault modelling is critical to plan for the future.
- Deploy fast stability solutions: Utilligence is developing power mitigation solutions capable of arresting grid collapses and large scale power outages in seconds.
Conclusion: It’s time for renewable-ready grids
While theories abound, the Spain-Portugal blackout was likely a failure of preparation, not of extraterrestrial forces. The energy transition demands grids that can handle faults without collapsing. The solutions exist—and recent events should provide the urgency to implement them