BYD to Supply Batteries for Poland’s Largest BESS Project
Greenvolt Power has begun construction on the Siedlce battery storage facility, with BYD Energy Storage supplying 210 battery containers and 105 transformer containers for the Polish grid asset.
September 26, 2026 — Greenvolt Power has started construction on the 600 MW/2.4 GWh Siedlce battery energy storage system in Poland, which will be the country’s largest BESS and one of Europe’s largest. BYD Energy Storage will supply the battery technology, including 210 battery containers and 105 transformer containers, with commercial operation targeted by the end of 2027.
Key Takeaways
- Siedlce is a 600 MW/2.4 GWh battery storage project in Poland, being built by Greenvolt Power, with commercial operation scheduled by the end of 2027.
- BYD Energy Storage is supplying the battery technology for Siedlce, with a design comprising 210 battery containers and 105 transformer containers housing power conversion systems.
- Siedlce will be Poland’s largest BESS facility and is described by Greenvolt as one of the largest battery storage projects in Europe.
- Greenvolt Power already operates two smaller Polish BESS projects using the same 200 MW/800 MWh configuration: Turośń Kościelna (operational since July 2026) and Ełk (targeted for Q4 2026); together with Siedlce, the three will total 1 GW/4 GWh.
- Greenvolt’s broader battery storage pipeline stands at approximately 4.6 GW on a probability-weighted basis, of which around 2.4 GW is located in Poland.
BYD Energy Storage’s Equipment Scope at Siedlce
According to Greenvolt Power, BYD Energy Storage has been selected as battery technology supplier for the Siedlce project, with a design that includes 210 battery containers and 105 transformer containers equipped with power conversion systems that enable electricity to flow between the batteries and the grid. The roughly 2:1 ratio of battery containers to transformer/power-conversion containers reflects the system architecture Greenvolt has disclosed for the site, though the companies have not published individual container capacity specifications in the material reviewed. At 600 MW of power and 2.4 GWh of energy capacity, Siedlce represents one of the larger single-site deployments for BYD’s containerized battery systems in the European market, according to Greenvolt’s announcement, positioning the supplier alongside the project’s other named contractors as the asset moves from planning into physical construction.
Project Scale and Timeline
Greenvolt Group, operating through its utility-scale renewable energy business Greenvolt Power, has begun construction on Siedlce, which the company states will be Poland’s largest battery energy storage facility and one of the largest in Europe. Commercial operation is scheduled to begin by the end of 2027, according to Greenvolt. Greenvolt Power is working with engineering and construction company P&Q and renewable energy contractor and developer ONDE on the project’s electrical infrastructure. Per the company’s statement, this division of labor leaves BYD Energy Storage responsible for the battery technology itself, while the electrical balance-of-plant work is handled by the two named contractors.
Part of a Growing Polish BESS Track Record
Siedlce builds on Greenvolt Power’s existing battery storage footprint in Poland. The Turośń Kościelna project, at 200 MW/800 MWh, entered operation in July 2026, according to Greenvolt, while the similarly sized Ełk project, also 200 MW/800 MWh, is expected to reach commercial operation in the fourth quarter of this year. Once Siedlce joins these two facilities, Greenvolt states the combined three-project fleet will provide 1 GW of power and 4 GWh of storage capacity in Poland. The supplied material does not specify whether BYD Energy Storage also supplied the battery technology for Turośń Kościelna and Ełk, which is flagged below as a gap for editorial follow-up.
Greenvolt’s Wider Battery Storage Pipeline
Battery storage is described by Greenvolt as an increasingly important part of its growth strategy, spanning utility-scale projects like Siedlce and behind-the-meter solutions for commercial and industrial customers offered through Greenvolt Next. According to Greenvolt, the company’s probability-weighted BESS pipeline totals approximately 4.6 GW across its European markets, with around 2.4 GW of that pipeline located in Poland alone. CEO João Manso Neto framed the project as evidence of execution against that pipeline: “With Siedlce, we are once again moving from plans to delivery.” The scale of the Polish pipeline suggests BYD Energy Storage’s role at Siedlce could be a reference point for how Greenvolt sources battery technology on future Polish projects, though the source material does not confirm any exclusivity or framework agreement between the two companies.
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, the CEO of Greenvolt Group.
Source: Greenvolt
I'm Amelia Bonner, an energy storage researcher and technical content writer focused on the technologies shaping the future of reliable, flexible, and sustainable energy systems. My work explores battery energy storage, grid-scale storage, renewable energy integration, battery technologies, and emerging energy storage solutions.
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