Greenvolt Power has started construction of a 600 MW/2.4 GWh battery energy storage system (BESS) in Siedlce, Poland, with commercial operation targeted for the end of 2027.
The project is expected to be Poland’s largest battery storage facility and among the larger BESS developments in Europe. Once operational, Siedlce will store electricity during periods of high renewable generation and discharge it when demand rises, providing additional flexibility to the Polish power system.
The project is designed to support the integration of wind and solar generation by helping balance electricity supply and demand as the share of variable renewable generation increases.
Greenvolt said Siedlce forms part of a probability-weighted battery storage pipeline of around 4.6 GW, including approximately 2.4 GW in Poland. The company is developing both utility-scale storage through Greenvolt Power and behind-the-meter systems for commercial and industrial customers through Greenvolt Next.
João Manso Neto, CEO of Greenvolt Group, said the Siedlce project marked a move from development into construction.
“What matters the most is building assets, creating real value and strengthening the infrastructure needed to integrate more renewable energy into the system,” he said.
Siedlce follows two other large battery projects being developed by Greenvolt Power in Poland. The 200 MW/800 MWh Turośń Kościelna facility entered operation in July 2026, while the similarly sized Ełk project is scheduled to enter commercial operation in the fourth quarter of 2026.
Together, the three projects will provide 1 GW of power capacity and 4 GWh of storage once operational.
BYD Energy Storage will supply the battery technology for Siedlce. The facility will comprise 210 battery containers and 105 transformer containers equipped with power conversion systems.
Engineering and construction company P&Q and renewable energy contractor and developer ONDE are supporting Greenvolt Power with the project’s electrical infrastructure.
