Battery financing in Southeast Europe increasingly depends on whether balancing revenues can support debt as energy spreads compress and storage capacity expands. In Hungary, grid-scale battery capacity had passed 1 GW by October, while lenders face the risk that ancillary-service demand may not grow in line with installed capacity. Market saturation is a separate risk from day-ahead arbitrage, and the income streams need to be assessed independently.
Romania had 1,162 MW of storage by 1 October. In Hungary, storage capacity increased from 197 MW in January to more than 700 MW and 1,400 MWh by 18 August. These figures illustrate the appeal of fast-response battery revenues and the risk that ancillary-service demand will not rise one-for-one with installed capacity.
Balancing and ancillary services can help distinguish projects capable of supporting debt from equity-heavy merchant projects that rely on day-ahead arbitrage. However, ancillary-service markets can saturate faster than day-ahead trading. Batteries may qualify for frequency or balancing products without securing sustainable revenues, as clearing prices can fall sharply when more batteries compete.
Eligibility to earn revenue does not guarantee income, and operating requirements can also constrain trading. Availability obligations, response times, state-of-charge management and penalties may reduce the capacity available for energy arbitrage. Lenders therefore need to distinguish between revenue a project is technically able to earn and revenue it can obtain sustainably.
Bitola project combines system services and market revenues
North Macedonia plans a 100 MW / 400 MWh battery in Bitola, with balancing capability defined as a project objective rather than an optional merchant-revenue opportunity. The project is valued at EUR 98 million and is being structured with sovereign-guaranteed and concessional finance. Its value is described as covering reliability, curtailment reduction and system services, as well as trading margin.
The planned structure reflects a model in which system services are part of the project’s purpose alongside market revenues. A bankable battery model for Southeast Europe should combine arbitrage, balancing and capacity-like income while applying independent haircuts to each. The revenue pools should not be stress-tested using the same correlation assumption.
The strongest projects will demonstrate that they can service debt even if one revenue pool becomes crowded.