Greenvolt Group, through Greenvolt Power, its utility-scale renewable energy business, has started construction of the 600MW/2.4GWh Siedlce battery energy storage system (BESS) in Poland. The project will be country’s largest BESS facility and one of the largest in Europe, with commercial operation scheduled to begin by the end of 2027.
Siedlce is part of Greenvolt’s growing battery storage portfolio, which currently has a probability-weighted BESS pipeline of approximately 4.6GW, including around 2.4GW in Poland. Battery storage is becoming an increasingly important part of Greenvolt’s growth strategy, spanning both utility-scale projects and behind-the-meter solutions for commercial and industrial customers across several European markets, through Greenvolt Next.
“With Siedlce, we are once again moving from plans to delivery. What matters the most is building assets, creating real value and strengthening the infrastructure needed to integrate more renewable energy into the system. Poland is a key market for us, and battery storage is becoming an increasingly important part of our growth,” said João Manso Neto, CEO of Greenvolt Group.
With 600MW of power and 2.4GWh of storage capacity, Siedlce will provide additional flexibility to the Polish power system by storing electricity during periods of high renewable generation and making it available when demand increases. This will support the integration of wind and solar generation and help balance electricity supply and demand.
Siedlce builds on Greenvolt Power’s growing battery storage track record in Poland. Turośń Kościelna, with 200MW/800MWh, entered operation in July 2026, while Ełk, also 200MW/800MWh, is expected to reach commercial operation in the fourth quarter of this year. Once all three projects are operational, they will provide a combined 1GW of power and 4GWh of storage capacity.
“We are now moving Siedlce into construction, with the battery supply and grid connection agreements in place. The experience we have gained from Turośń Kościelna and Ełk gives us a strong basis for delivering a project of this scale, and our priority is to keep that momentum and bring Siedlce into operation by the end of 2027,” said Weronika Nowak, CEO of Greenvolt Power.
BYD Energy Storage will supply the battery technology. The project design includes 210 battery containers and 105 transformer containers equipped with power conversion systems, enabling electricity to flow between the batteries and the grid.
Greenvolt Power is working with engineering and construction company P&Q and renewable energy contractor and developer ONDE on the project’s electrical infrastructure.
