Southeast Europe’s rapid solar and wind build-out is reviving interest in one of the region’s oldest flexibility technologies: pumped-storage hydropower. Serbia’s planned Bistrica project is the clearest example. With approximately 680 MW of proposed generating capacity and an estimated cost of about €1.2 billion, it would be among the country’s largest energy investments.
The operating principle is simple. When electricity is abundant and inexpensive, water is pumped to an upper reservoir. It is released through turbines when demand and prices rise. The plant consumes more energy than it produces over a full cycle, but it converts low-value electricity into dispatchable peak power and provides reserves, inertia and other grid services.
Bistrica’s strategic value is growing because SEE’s hourly price profile is changing. Solar output increasingly depresses prices around midday, while evening prices rise sharply after sunset. Batteries are well suited to fast, short-duration balancing, but a large pumped-storage plant can store substantially more energy and may operate for many decades. The technologies are complementary rather than mutually exclusive.
Serbia approved the spatial plan for Bistrica and has explored Japanese participation, with an objective of bringing the plant online early in the next decade. Yet its economics require careful examination. A €1.2 billion estimate is not a secured financing package, and major civil works face geological, environmental and construction risks. Revenue from arbitrage alone may not support such a capital-intensive asset. Capacity payments, ancillary-service income or a regulated system-value mechanism may be necessary.
Existing hydro infrastructure can often provide lower-risk gains. Romania’s Hidroelectrica signed a €188 million contract in May 2026 to refurbish the 335 MW Râul Mare Retezat plant. Modernisation can extend asset life, improve efficiency and reliability, and add flexible output without constructing an entirely new dam. Serbia is similarly preparing the long-delayed reconstruction of the four-plant Vlasinske cascade with EBRD and EU support.
This creates two distinct hydro investment markets in SEE. The first is refurbishment: relatively defined projects that recover lost performance and adapt ageing plants to a more variable power system. The second is new pumped storage: larger, slower and more complex developments whose value depends on future market design.
Environmental and social impacts remain central. New reservoirs can alter river ecology, inundate land and displace communities. Albania’s proposed Skavica dam illustrates the conflict. Public estimates have risen from earlier ranges of €308–510 million to more than €1 billion in some assessments, while financing remains uncertain and opposition focuses on displacement and the loss of the Black Drin’s remaining free-flowing section. The Western Balkans Investment Framework describes a 132 MW scheme producing about 450 GWh annually, but the project’s status and design remain contested.
The strongest SEE hydro strategy is therefore selective, not indiscriminate: refurbish high-value existing assets, develop pumped storage where system benefits justify the cost, and avoid treating every dam proposal as automatically green. In a renewable-heavy market, flexible water storage may be worth more than additional annual generation—but only if its financial, ecological and social costs are transparent.
