July generation outlook for HSE river systems
Holding Slovenske Elektrarne expects hydropower production from the Drava, Soča and lower Sava to contract sharply in July. Output is forecast to be 39% lower than in July 2025. It is also expected to run at approximately 52% below the five-year monthly average.
The company links the decline to drought conditions and exceptionally low river levels affecting generation at those plants. The expectation covers July production from the river systems mentioned, with the impact tied to reduced water availability.
Conditions after a stronger June and weaker rainfall
The deterioration follows a comparatively strong June for hydropower output. In June, generation was 4% higher year on year. After that period, river conditions weakened rapidly as rainfall stayed limited.
High temperatures then increased evaporation, further reducing river flows feeding hydropower plants. This combination of limited precipitation and elevated evaporation is cited as the driver behind the rapid change in conditions.
Broader deficit across early 2026 and low-flow levels by late July
Across the first half of 2026, production from HSE’s hydropower plants was 31% below the same period of 2025. It was also 38% below the five-year average. The data indicate that the July weakness reflects a broader hydrological shortfall rather than an isolated monthly move.
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.
Market implications for flexible power and regional trading
Lower hydroelectric output reduces Slovenia’s normally flexible generation position. It also increases sensitivity to imported electricity. At the same time, reduced dispatchable renewable supply affects participation in a regional market with existing constraints.
The market context includes poor hydrology in Serbia and cooling-water concerns along the Danube. The financial effect on HSE depends on hedge coverage, import costs and performance of its trading portfolio . Hydrological losses are described as especially costly when they align with high regional evening prices, since production is lost during hours when flexible hydro capacity would otherwise capture its highest value .
