Slovenian energy group GEN-I has entered Bulgaria’s commercial battery market by taking over optimisation and market management of a 50 MW/126 MWh storage facility developed by SUNOTEC at Byala Slatina. The project provides approximately 2.5 hours of storage duration.
The facility is positioned to participate in day-ahead and intraday trading, as well as balancing and ancillary-service markets. GEN-I will manage the asset under a five-year partnership. The arrangement combines a secured baseline-revenue component with market optimisation designed to capture additional income from price volatility.
Asset ownership and commercial operation split
The operating structure separates physical ownership from commercial dispatch responsibilities. SUNOTEC retains the physical project, while GEN-I applies forecasting, trading and dispatch capabilities. This model enables specialist market operators to aggregate larger storage portfolios without financing each battery directly.
Pipeline targets across Bulgaria and Romania
GEN-I and SUNOTEC are also working on additional investments beyond the Byala Slatina mandate. The Slovenian group aims to have around 800 MW of battery capacity under management by the end of 2026, primarily across Bulgaria and Romania.
GEN-I Invest has acquired three Bulgarian battery projects in Belovo, Momchilgrad, and Parvomay. The combined capacity totals 30 MW/76 MWh. Alongside its existing 12 MW/24 MWh facility near Talum, the transactions increase GEN-I Invest’s directly owned storage portfolio to 42 MW/100 MWh.
Implications for short-duration market participation
The Byala Slatina mandate is larger than GEN-I’s current owned portfolio, reflecting the scale that can be accessed through third-party management. It places the company in a Bulgarian market with strong solar development, widening midday-to-evening spreads, and growing demand for balancing capacity.
The commercial setup focuses on protecting minimum contracted revenues while maintaining exposure to short-duration price spikes. Under the five-year arrangement, SUNOTEC receives greater revenue visibility, while GEN-I builds a regional portfolio intended to support more sophisticated market access and dispatch strategies.
