Final analysis of 2025 Iberian blackout: Policies left Spain at risk

Data collection status logs and device data were collected, the committee accessed sub-second logs from major hardware, interchange data, and rooftop inverter manufacturer data.

Oscillations two distinct oscillations were recorded, one matched a known east–west European grid mode; the other traced to an interface near a Spanish generating station.

Oscillations did not directly cause the blackout, the final report states the oscillations themselves were not the direct cause of the outage.

Damping measures increased reactive power and raised transmission voltage, spain's oscillation-dampening response increased reactive power and elevated voltages on the 400 kV grid.

Grid voltage voltages rose above normal operating range to over 420 kV, after the second oscillation, voltages peaked at more than 420 kV.