The most valuable market for stored electricity in Southeast Europe depends on how a battery will earn revenue, not simply on average electricity prices or installed capacity. The ranking can differ for merchant traders, banks and portfolio owners, making net returns per usable megawatt-hour the relevant comparison.
Storage earns money from price differences between hours and from system services. A market’s average day-ahead price alone does not capture the value of that flexibility: comparisons also need to account for volatility, competition, grid charges, fees, degradation and the depth and accessibility of balancing markets. Revenue per usable MWh after those factors is a better measure of value.
Capacity figures indicate the different scales of the markets. Hungary had 1,053.4 MW of grid-scale battery capacity listed at 1 October. Romania had 1,162 MW and 2,312 MWh of storage capacity at 1 October, while Bulgaria had more than 6.2 GW and 19 GWh by the latest estimates.
Bulgaria’s large fleet offers scale and sophisticated storage operations, but also brings intense competition for arbitrage. Portfolio owners may favour the market because storage can be paired with large solar assets and mature dispatch experience. Romania combines a rapidly growing fleet with strong merchant and balancing opportunities; its non-recourse precedent may also make it the preferred option for a bank.
Hungary’s storage expansion is supported by market reform and a large solar base. Serbia’s operating fleet remains smaller than those of the other countries discussed, but scarcer flexibility can mean stronger price volatility and wider scarcity margins. Standalone storage there, however, carries more regulatory and financing uncertainty. A pure merchant trader may therefore prefer a less saturated market, while other investors may place greater weight on scale, financing precedent or portfolio fit.
Investors should model the same battery configuration in each market using identical technical assumptions before deciding where it is worth most. The comparison should include competition, market-access costs, fees, degradation and balancing access, rather than use average spot prices or installed capacity alone.