Slovenian energy group GEN-I has entered Bulgaria’s commercial battery market by taking over the optimisation and market management of a 50 MW/126 MWh storage facility developed by SUNOTEC at Byala Slatina.
The system offers approximately 2.5 hours of storage duration, giving it the flexibility to participate in day-ahead and intraday trading as well as balancing and ancillary-service markets. GEN-I will manage the facility under a five-year partnership, combining a secured baseline-revenue arrangement with market optimisation intended to capture additional income from price volatility.
The structure is important because it separates asset ownership from commercial operation. SUNOTEC retains the physical project, while GEN-I applies its forecasting, trading and dispatch capabilities. This model allows specialist market operators to aggregate larger storage portfolios without financing every battery directly.
GEN-I and SUNOTEC are already working on additional investments. The Slovenian group aims to have around 800 MW of battery capacity under management by the end of 2026, principally across Bulgaria and Romania.
GEN-I Invest has also acquired three Bulgarian battery projects in Belovo, Momchilgrad and Parvomay, with combined capacity of 30 MW/76 MWh. Together with its existing 12 MW/24 MWh facility near Talum in Slovenia, the transactions have increased its directly owned storage portfolio to 42 MW/100 MWh.
The Byala Slatina mandate is larger than GEN-I’s current owned portfolio and illustrates the scale available through third-party management. It also places the company in a Bulgarian market characterised by strong solar development, widening midday-to-evening spreads and growing demand for balancing capacity.
The commercial challenge will be to protect minimum contracted revenues without surrendering too much upside from short-duration price spikes. GEN-I’s five-year arrangement gives SUNOTEC greater revenue visibility while allowing the trading company to build a regional portfolio whose combined size can support more sophisticated market access and dispatch strategies.
