Slovenia’s hydropower generation is expected to fall sharply as drought and exceptionally low river levels affect plants on the Drava, Soča and lower Sava.
Holding Slovenske Elektrarne expects July production from these river systems to be 39 per cent lower than in July 2025 and approximately 52 per cent below the five-year monthly average.
The deterioration follows a comparatively strong June, when hydropower output was 4 per cent higher year on year. River conditions then weakened rapidly as rainfall remained limited and high temperatures increased evaporation.
Across the first half of 2026, production from HSE’s hydropower plants was 31 per cent below the same period of 2025 and 38 per cent below the five-year average. The figures show that July’s weakness is part of a broader hydrological deficit rather than an isolated monthly disturbance.
By the end of July, flows on the Drava, Sava, Soča and most other major rivers were close to the lowest levels recorded for that month during the past decade. Another heatwave expected to last at least ten days could reduce flows further.
Lower hydroelectric production weakens Slovenia’s normally flexible generation position and increases its sensitivity to imported electricity. It also removes dispatchable renewable output from a regional market already dealing with poor hydrology in Serbia and cooling-water concerns along the Danube.
The financial effect on HSE will depend on hedge coverage, import costs and the performance of its trading portfolio. Hydrological losses are particularly expensive when they coincide with high regional evening prices, because the group loses production during the hours in which flexible hydro capacity would otherwise capture its highest value.
