Hydropower, a key source of flexibility in Southeast Europe during periods of high electricity demand, weakened during Week 26 (22–28 June 2026). Regional hydroelectric generation fell 2.8% week on week to 3.51 TWh. Lower production in Türkiye and Bulgaria outweighed stronger output in Serbia, Croatia, Greece, Romania and Italy. The decline coincided with rising temperatures and higher cooling demand that were already adding pressure to regional power systems.
Regional hydro generation drops to 3.51 TWh
The reduction in hydro output was not uniform across markets, but its effect on price formation was described as significant. Türkiye, the largest hydro producer in Southeast Europe, saw a 5.9% weekly decline, cutting regional hydro availability by 142 GWh. Bulgaria recorded the steepest fall, with hydro generation down 44.6% versus the previous week. With electricity consumption increasing strongly across the region, reduced hydro output meant less low-cost and flexible generation was available to support the system and limit wholesale price increases.
Mixed national performance across Balkan hydropower fleets
Some countries recorded gains despite the regional decline. Serbia’s hydro generation rose by 121.5%, while Croatia reported a 93.8% increase. The source data indicates these percentage increases followed recovery from relatively low prior production levels and were not enough to offset declines elsewhere. Greece increased hydro output by 12.1%, while Romania and Italy also posted moderate improvements.
Dispatchable flexibility and implications for thermal reliance
The role of hydropower extends beyond total energy volumes in the regional system. Hydro assets provide dispatchable flexibility that helps power systems respond quickly when solar generation drops in the evening while demand remains elevated. When hydro resources are limited, unevenly available or conserved, the region becomes more dependent on gas-fired generation, coal and lignite plants, along with cross-border imports. That shift increases exposure to higher marginal electricity prices.
Bulgaria’s export position remains tied to hydro conditions
Bulgaria’s situation was highlighted for its relevance to regional trading flows. Even with lower hydro production, Bulgaria stayed an important net electricity exporter, requiring other generation sources 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.
Market expectations under changing water availability
Hydropower availability also influences market expectations and trading strategies during the summer season. When water availability is strong, Balkan electricity markets can see lower prices, particularly during off-peak hours and periods of high renewable output. During dry conditions or constrained hydro availability, prices can tighten quickly, especially when heatwaves raise consumption levels. Week 26 showed that even a relatively small regional hydro decline can affect pricing when demand growth is already running at double-digit rates.
Summer outlook: monitoring reservoirs and dispatch strategy
Hydro conditions are expected to become an increasingly important factor for Southeast Europe’s summer electricity outlook. Market participants are expected to track gas prices and renewable generation alongside reservoir levels, river flows, pumped-storage availability and hydro dispatch strategies. The ability of hydro operators to preserve water resources for higher-value peak periods is cited as a factor that can affect electricity price volatility throughout the summer.
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