Hidroelektrane na Trebišnjici, the hydropower subsidiary of Elektroprivreda Republike Srpske, produced 690 GWh of electricity during the first half of 2026, exceeding its plan by 66 GWh and remaining the largest generator in Republika Srpska.
Production was approximately 10.5% above target. HET had already achieved 64% of its annual generation plan by the end of June, while completed output and the energy value of available reservoir reserves together represented about 85% of the expected annual total.
The strong result was secured largely during the opening months of the year. Rainfall across the Trebišnjica basin reached approximately 880 litres per square metre, allowing the company to capture high inflows and raise the Bileća reservoir to its highest level of the year on 25 February.
Conditions then reversed. The March-to-June period was exceptionally dry, forcing HET to manage the reservoir more conservatively as inflows fell below historical averages. The contrast between intense short rainfall episodes and prolonged dry periods is making hydropower scheduling increasingly complex.
The Bileća reservoir stands at approximately 371 metres above sea level, around 10 metres below its planned level. Management nevertheless considers the remaining water reserve sufficient to keep production near its annual target, particularly with additional precipitation expected during the autumn.
HET’s performance has wider financial importance for ERS. Hydropower output has low marginal costs and can be dispatched during higher-priced periods, making it particularly valuable when the group’s coal plants are unavailable or operating below plan. Every additional megawatt-hour generated from stored water can reduce the need for imported electricity or preserve thermal fuel stocks.
The result also illustrates the difference between generation volume and hydropower value. Reservoir operators must decide whether to produce immediately, conserve water for later peak periods or retain reserves for system security. Strong first-half output improves near-term cash generation, but a low reservoir level can limit flexibility during the late-summer period.
HET’s ability to finish the year above plan will depend on autumn hydrology and the dispatch required from ERS. The company enters the second half with a sizeable production advantage, but with less comfortable water conditions than those that supported its first-quarter performance.
