Battery storage in south-east Europe is moving from demonstration projects into market infrastructure. Bulgaria and Romania are now showing how batteries are becoming revenue assets for balancing, ancillary services, renewable integration and grid stability. The shift is important because SEE power markets are entering a phase where price volatility, negative-price risk and congestion will increasingly determine project economics.
Bulgaria is the most visible early mover. The country is expected to reach 3 GWh of battery storage capacity by the end of 2026. Projects include Knizhnovik Phase 1, a 100 MW / 200 MWh hybrid BESS and PV project developed by Enery, and Nova Zagora, one of Bulgaria’s first utility-scale stand-alone battery installations fully compliant with national grid regulations.
The scale is accelerating. A 150 MW / 600 MWh Bulgarian facility linked to Sungrow and Sunotec is described as a major milestone in a broader storage collaboration, with up to 800 MWh in the Nova Zagora region and further expansion of up to 1 GWh under consideration. Over a two-month period, 2.2 GWh of battery storage capacity is scheduled to come online, with total capacity expected to reach 3 GWh by the end of 2026.
Sermatec has also commissioned a 10 MW / 31 MWh BESS in Bulgaria. The facility uses containerised batteries and an intelligent energy management system enabling participation in both the electricity market and ancillary services. That detail matters because battery value is no longer limited to storing cheap electricity and selling it later. It increasingly depends on optimisation across multiple revenue streams.
Romania is moving through a different route. PPC Renewables Romania is adding a 4.47 MW / 8.94 MWh BESS to the Colibași photovoltaic park in Giurgiu County. The investment totals RON 10.56mn, with RON 1.91mn from the Modernisation Fund and RON 8.65mn from PPC Renewables Romania. This is a retrofit model: adding storage to an existing solar asset to improve dispatchability and market value.
The market signal is clear. Batteries are becoming part of the commercial architecture of SEE electricity. Developers, traders and utilities that can optimise storage across day-ahead, intraday and balancing markets will have a structural advantage. The next renewable cycle will not be won only by securing land, permits and grid connection. It will be won by controlling flexibility.
