Hidroelektrane na Trebišnjici, the hydropower unit of Elektroprivreda Republike Srpske, produced 690 GWh of electricity in the first half of 2026. Output exceeded its plan by 66 GWh and remained the largest generation source in Republika Srpska. Production was about 10.5% above target. By the end of June, HET had reached 64% of its annual generation plan.
Completed output together with the energy value of available reservoir reserves accounted for roughly 85% of the expected annual total. The company’s results were driven mainly by conditions in the opening months of the year. Rainfall across the Trebišnjica basin reached approximately 880 litres per square metre. This enabled higher inflows and helped lift the Bileća reservoir to its highest level of the year on 25 February.
Dry spring affects reservoir management and dispatch planning
After February, conditions shifted as the March-to-June period turned exceptionally dry. HET managed the reservoir more conservatively as inflows fell below historical averages. The pattern of intense short rainfall episodes followed by prolonged dry stretches is making hydropower scheduling increasingly complex. The Bileća reservoir level stood at about 371 metres above sea level, around 10 metres below its planned level.
Management said remaining water reserves are sufficient to keep production close to its annual target. Additional precipitation is expected during autumn, according to the company’s assessment. The operational constraints during the dry months also affect how much flexibility is available for later periods. With lower reservoir levels, dispatch options can tighten toward late summer.
Hydropower output role within ERS generation mix
HET’s generation has broader financial relevance for ERS because hydropower has low marginal costs. It can be dispatched during higher-priced periods, which is particularly relevant when ERS’s coal plants are unavailable or operating below plan. The company said each additional megawatt-hour generated from stored water can reduce reliance on imported electricity or help preserve thermal fuel stocks.
The reporting also highlights differences between generation volume and hydropower value for system operations. Reservoir operators must balance producing immediately against conserving water for later peak periods, or retaining reserves for system security. Strong first-half output supports near-term cash generation, while a lower reservoir level can limit flexibility during late-summer conditions.
Whether HET can finish the year above plan will depend on autumn hydrology and dispatch requirements from ERS. The company enters the second half with a production advantage, but with less comfortable water conditions than those that supported its first-quarter performance.
