Greenvolt Starts Building 2.4 GWh Poland Battery Project With BYD Supply Deal

Greenvolt has started construction on its Siedlce battery energy storage project in Poland, a 600 MW/2.4 GWh facility that the Portuguese renewables developer and its supplier, BYD Energy Storage, describe as set to become one of the largest of its kind in Europe. BYD is supplying the project’s battery systems under a deal the two companies signed earlier this year, and commercial operation is targeted for the end of 2027.

A project already earning revenue before it is built

Siedlce has already secured contracted revenue through Poland’s capacity market mechanism, the auction system Poland uses to pay generation and storage assets for being available to the grid rather than only for the electricity they sell. That gives the project a revenue floor independent of wholesale battery arbitrage, which is one reason Greenvolt and BYD are willing to build at this scale before Poland’s storage market has fully matured. The battery technology itself is BYD’s Haohan storage system, the same platform the two companies have already deployed on two smaller Polish projects.

Not BYD and Greenvolt’s first Polish project together

Siedlce builds directly on a working relationship: BYD Energy Storage previously supplied Greenvolt’s Turośń Kościelna and Nowa Wieś Ełcka projects in Poland, each rated at 200 MW/800 MWh. Combined with Siedlce, that puts more than 1,000 MW and 4 GWh of BYD-supplied storage capacity across three Greenvolt sites in the country — a repeat-customer pattern that reflects both confidence in the supply relationship and BYD’s push to establish itself as a top-tier battery supplier in the European utility-scale market.

Part of a much larger Polish and global pipeline

Siedlce is the largest single project in a Greenvolt storage pipeline that totals roughly 2.6 GW in Poland alone, alongside 238 MW of wind and 657 MW of solar the company has under development in the country. Globally, Greenvolt’s portfolio runs to around 13 GW across generation and storage. Poland has become one of Europe’s most active battery storage markets over the past two years as grid operators there lean on capacity-market auctions to attract exactly this kind of flexible capacity, needed to firm up the country’s fast-growing wind and solar fleet.

What comes next

With construction now under way, the project’s next checkpoints are equipment delivery and grid-connection milestones over the roughly 15 months until the end-of-2027 commercial operation target. Because Siedlce’s revenue is already anchored in a capacity-market contract, the bigger open question for Greenvolt is less about this project’s economics than about how much of its remaining 2.6 GW Polish storage pipeline can secure similar contracted revenue as Poland’s capacity auctions become more competitive.

Sources: Energy-Storage.News, “Greenvolt starts building 2.4GWh, BYD-supplied Poland BESS; 900MWh progressed elsewhere in CEE/Baltics,” Sept. 24, 2026, energy-storage.news — construction start, capacity figures and commercial-operation target; Enerdata, “Greenvolt secures supply deal for its 600 MW/2.4 GWh BESS in Poland,” 2026, enerdata.net — BYD supply agreement and technology; Argus Media, “BYD, Greenvolt to develop Poland energy storage project,” 2026, argusmedia.com — prior Turośń Kościelna and Nowa Wieś Ełcka projects and portfolio figures.

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Illustrative image. Photo: Kecko from Eastern Switzerland, CC BY 2.0, via Wikimedia Commons — source