Slovenia’s hydropower slump in early 2026 shifts generation burden to thermal and nuclear

Slovenia’s electricity balance took a hit at the start of 2026 as generation from its major rivers declined markedly, forcing conventional power to fill the shortfall. With hydropower underperforming against both last year and long-term expectations, the country leaned more heavily on nuclear and thermal output to maintain supply through the first quarter.

Hydropower delivery falls across Drava, Sava and Soča

Electricity delivered to the transmission network from hydropower plants along the Drava, Sava and Soča rivers totaled 718 GWh in the first quarter. That was down 23.1% year-on-year and also 10.5% below long-term expectations, pointing to weaker-than-expected hydrological conditions across Slovenia’s system.

The decline was broad-based across all three river basins. The largest deviations were reported on the Drava and in the upper Sava region, where river flows stayed low to below average through winter. Limited snow reserves in the Alps further reduced expectations for spring inflows, leaving hydropower availability constrained into the season.

Thermal and nuclear output rises to compensate

As hydropower delivered less electricity, other generation sources increased output to meet demand. Krško Nuclear Power Plant generated 1,516 GWh in the first quarter, while Šoštanj Thermal Power Plant contributed 666.3 GWh.

Thermal generation showed some of the sharpest adjustments. TE-TO Ljubljana produced 311.9 GWh—nearly 120% higher than a year earlier—after commissioning of a new gas-fired unit, underscoring how quickly thermal flexibility can be brought to bear when water conditions deteriorate.

Brestanica thermal power plant also added support, with production rising by about 53% year-on-year to 14.8 GWh. Even with these increases, the pattern reflects a wider shift toward conventional generation aimed at stabilizing supply when hydropower is insufficient.

Domestic supply declines versus both last year and plan

Total electricity supplied from domestic sources reached 3,226.7 GWh between January and March 2026. That represented a 5.5% decrease compared with the same period in 2025 and left supply 1.9% below planned levels.

Taken together, the figures show how reduced hydropower output can quickly propagate through Slovenia’s generation mix—raising reliance on nuclear and thermal plants while still leaving overall domestic supply slightly short of plan during a season shaped by low river flows and weaker snowpack.