Hydropower is widely regarded as a stabilising element in Southeast Europe’s electricity markets, but Week 25 showed it can also contribute to volatility. Regional hydro generation fell by nearly 5% while solar output rose across several markets. The tighter supply conditions increased reliance on thermal generation and affected regional power-price formation.
Week 25: hydro availability and regional price formation
Hydropower’s role goes beyond its share of electricity production, providing flexibility through balancing services, operating reserves, and price stability. Hydro plants can respond quickly to changes in demand and generation conditions, supporting the integration of wind and solar. When hydro availability weakens, systems can become more exposed to gas-fired generation, coal plants, cross-border imports, and peak-hour scarcity.
Week 25 illustrated these effects in different national outcomes. In Romania, electricity demand declined but market prices increased as weaker hydro generation reduced supply flexibility. Regional market coupling also pushed prices on OPCOM higher.
Serbia saw the opposite direction during the same period. Stronger hydro output helped the system move into an export position and eased domestic market pressures. The contrasting results pointed to hydrological conditions acting as a stronger driver of national electricity prices than demand trends alone.
Implications for renewables economics and system balancing
Hydro variability affects how solar and wind generation performs within the wider system. Solar and wind depend on the system’s ability to absorb and balance variable output. When hydro availability is strong, balancing costs are often lower, system flexibility improves, and curtailment risks can decline.
When hydro generation weakens, additional thermal flexibility is required. That shift increases market volatility and changes the revenue environment for renewable assets. It can influence merchant revenues, PPA pricing, financing assumptions, and risk assessments used by lenders and investors.
Climate-driven hydrology risk in long-term forecasts
The impact of climate variability increases the relevance of hydrological uncertainty for market analysis. Hydropower systems across Southeast Europe depend on rainfall patterns, snowpack levels, river flows, and exposure to seasonal droughts. Forecasting approaches therefore need to reflect different hydrological conditions rather than relying on a single set of assumptions.
Long-term electricity-price forecasts must include wet-year, normal-year, and dry-year scenarios. This requirement applies alongside other drivers such as fuel prices, carbon costs, or demand growth projections. Incorporating hydrological scenarios is presented as necessary for capturing how hydro availability can change over time.
Effects on utilities and flexible investment needs
For utilities, hydro assets function as strategic resources on balance sheets. During wet periods, strong hydro output can reduce fuel consumption, lower operating costs, strengthen export opportunities, and support profitability. During dry periods, utilities may need to increase imports and run more gas- and coal-fired generation while absorbing higher balancing costs.
Those operational shifts can affect earnings performance and working-capital requirements. They can also create additional pressure on regulated electricity tariffs. For battery storage investors and other flexible technologies, constrained hydro resources can raise the value of services that batteries provide.
Batteries can deliver balancing and ramping services that hydro would normally supply when availability is higher. As renewable penetration increases and weather-driven hydro variability becomes more pronounced, the value of flexible assets is expected to grow further in commercial terms.
Market reliability under changing hydro conditions
Hydropower remains a key advantage for Southeast Europe because it supports flexibility and system reliability across the region. At the same time, it is not treated as a guaranteed source of stability under changing weather conditions. Hydro variability continues to shape electricity prices, market dynamics, investment decisions, and energy-security outcomes.
Week 25 reinforced that point by showing hydro is not only a buffer against volatility but also one of its important drivers.
