Causes of July power outage in Czechia remain unclear, investigation continues

The causes of the widespread July power outage in Czechia remain unclear. The investigation into the incident has been ongoing for five months, with grid operator ČEPS currently analysing the collected data. In addition, an investigation by an Expert Panel is continuing and is expected to issue a preliminary report in January. ČEPS spokesperson Lukáš Hrabal told ČTK.

The massive power outage on 4 July, which lasted several hours, affected around one million customers. Czechia has 6.3 million connection points.

ČEPS launched an analysis of the outage with experts almost immediately, but the investigation has not yet been concluded. "In cooperation with market participants, it was necessary to collect a broad range of data for the investigation, with ČEPS receiving some of it from certain market participants only at the beginning of October. A detailed expert assessment of the additional data is currently under way so that the outage report can be completed," Hrabal said.

According to him, a further investigation is continuing at the level of the European Network of Transmission System Operators for Electricity (ENTSO-E), through an Expert Panel involving experts from various transmission system operators, including ČEPS, representatives of the Agency for the Cooperation of Energy Regulators (ACER), and national regulatory authorities. "The preliminary report is expected within six months of the incident, by January 2026 at the latest. The final report will then follow within 12 months, by July 2026," Hrabal said.

According to earlier reports by ČEPS, the widespread power outage in the Czech Republic resulted from a combination of several failures. It began with a snapped phase conductor, a cable that transmits electricity between power plants and substations. This took the key V411 line out of service; the line is used to transmit high volumes of output from power plants and transfer electricity over long distances. Shortly afterwards, a unit at the Ledvice power plant in the Teplice region and the large Krasíkov substation in the Ústí nad Orlicí region also tripped. Due to the heavy load, the control centre also disconnected the V208 line, which links substations. However, the reason for the combination of events remains unclear.

The grid operator has, however, ruled out grid overload caused by cross-border electricity flows or damage by a third party as the cause of the outage. The line whose failure led to the outage was already damaged last year, but without any further problems at the time.