In the early morning of 18 May 2025, a partial blackout occurred in the power system of North Macedonia. The incident resulted in a loss of almost all load in the electricity system for one and a half hours (from 04:59 to 06:27 CEST). The Transmission System Operator (MEPSO) quickly restored the network, and the rest of the European power system remained largely unaffected.
Before the partial blackout, unusually high voltages were observed on MEPSO’s network, along with very low consumption and very low cross-border electricity flows via interconnections with neighbouring TSOs.
ENTSO‑E has established an Expert Panel to perform a detailed investigation of this event. It reported that at 04:59 CEST on 18 May 2025, a separation occurred between the 400 kV and 110 kV transmission networks due to overvoltage. This event led to a full blackout in the 110 kV network, resulting in the loss of approximately 79 per cent of the total load in the country.
MEPSO immediately began system restoration, completing it by 07:47 CEST, less than three hours after the blackout. On the same day, the Bulgarian control area entered an alert state for eight hours due to high voltages in the western part of the system.
The factual report serves as the first major report of the Expert Panel and has been prepared in line with applicable regulations. The final step of the investigation will involve the release of the final report, expected in Q1 2026, which will include a detailed root cause analysis and recommendations to help prevent similar incidents in the future.