German-Bulgarian solar photovoltaic (PV) plant developer Sunotec and Slovenian energy group GEN-I have commissioned their 50 MW / 126 MWh battery energy storage system (BESS) in Byala Slatina, northwestern Bulgaria, Sunotec said.
The BESS has entered live commercial operation under GEN-I’s advanced optimisation and commercial asset management.
In Romania, Sunotec officially launched its local subsidiary last autumn. Since entering the Romanian market in early 2024, by the launch in October 2025 of Sunotec Romania, the company has already built 132 MWp of installed capacity and developed a pipeline exceeding 1 GWp of PV projects and 1 GWh of storage capacity planned for the next years.
Also, this June one of the Sunotec partners, Adex Energy, entered the Romanian market, by appointing Mihai-Florin Necula as Country Manager.
The launch of the new BESS system in Bulgaria marks the first operational milestone of Sunotec and GEN-I’s five-year partnership, announced last November. Under the partnership, the companies aim to develop and deliver large-scale BESS infrastructure, combining it with GEN-I’s energy trading capabilities, flexibility services and multi-market optimisation, Sunotec said, according to SeeNews.
In April, Sunotec announced a partnership structured equity investment from funds managed by U.S.-based investment firm Blackstone’s Tactical Opportunities fund.
In 2025, Sunotec signed a five-year cross-border spread hedge agreement with UK-based energy commodities trader Shell Energy Europe for its 600 MWh BESS project in Bulgaria. It also signed financing for six BESS projects and one co-located solar PV and BESS project in October 2025.
In June, GEN-I said it has successfully completed the acquisition of three BESS in Bulgaria. In February, the company announced it has entered the U.S. energy market by the opening of a subsidiary there – GEN-I Trading North America LLC.
