Hydropower contributed less to balancing during Week 26 (22–28 June 2026), when Southeast Europe faced higher electricity demand. Regional hydroelectric generation declined 2.8% week on week to 3.51 TWh. Lower output in Türkiye and Bulgaria outweighed stronger production in Serbia, Croatia, Greece, Romania and Italy. The decline also coincided with rising temperatures and increased cooling demand.
Week 26 hydro generation changes by country
The reduction in hydro production varied across markets, while its effect on price formation was described as significant. Türkiye, the largest hydro producer in Southeast Europe, recorded a 5.9% weekly decline, cutting regional hydro availability by 142 GWh. Bulgaria saw the steepest drop, with hydro generation falling 44.6% compared with the previous week. At the same time, electricity consumption increased strongly across the region.
Some countries recorded increases against the regional pattern. Serbia’s hydro generation rose by 121.5%, while Croatia recorded a 93.8% increase. The source data indicate that these percentage gains reflected recovery from relatively low prior output levels and were not enough to offset declines elsewhere. Greece increased hydro output by 12.1%, while Romania and Italy also reported moderate improvements.
Balancing role of hydropower during high demand
The balancing impact of hydropower extends beyond total energy volumes. Hydro assets provide dispatchable flexibility that enables power systems to respond quickly when solar generation declines in the evening while demand remains elevated. When hydro resources are limited, unevenly distributed or conserved for later use, the region relies more on gas-fired generation, coal and lignite plants, and cross-border imports. That shift increases exposure to higher marginal electricity prices.
Bulgaria’s situation was highlighted for its relevance to regional trading flows. Despite lower hydro production, Bulgaria remained an important net electricity exporter during Week 26. Other generation sources therefore had to compensate for reduced hydro availability while meeting domestic demand and export commitments. In neighboring markets including Greece, Romania and Serbia, hydro conditions affected how systems managed rising demand without increasing reliance on imports or higher-cost thermal generation.
Implications for market expectations and summer monitoring
Hydropower availability also influences expectations and trading strategies across Balkan power markets. When water availability is strong, prices can fall quickly, particularly during off-peak hours and periods of high renewable output. Under dry conditions or constrained hydro availability, prices can tighten rapidly, especially when heatwaves raise consumption levels. Week 26 showed that even a relatively small regional hydro decline can matter when demand is already growing at double-digit rates.
For the summer outlook in Southeast Europe, hydro conditions are expected to remain a key variable for market participants monitoring power system balance. Alongside gas prices and renewable generation, they are expected to track reservoir levels, river flows, pumped-storage availability and hydro dispatch strategies . The source also points to the role of operators preserving water resources for high-value peak periods in shaping electricity price volatility through the summer .
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