IPP Greenvolt Power has started building its Siedlce battery storage project in Poland, while Gore Street, Taaleri Energia and DS1 have moved to construction on projects in Poland, Estonia and Lithuania respectively.
It is our second regional roundup in two days as large-scale activity accelerates in the lead-up to the Energy Storage Summit Central and Eastern Europe (CEE) 2026, which runs on 6-7 October in Warsaw, Poland.
Greenvolt starts building one of Europe’s biggest BESS projects in Poland
Greenvolt has started construction on what will be Poland’s largest battery energy storage system (BESS) when online, the 600MW/2.4 GWh Siedlce project, with commercial operations targeted for end-2027.
The facility will also be among Europe’s largest BESS projects when it is completed at the end of 2027. Engineering and construction company P&Q and renewable energy contractor and developer ONDE are the project’s construction contractors.
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The news follows Greenvolt Power’s 200MW/800MWh Turośń Kościelna project entering commercial operations in July, while the identically-sized Nowa Wieś Ełcka project will come online in Q4 2026.
All three projects, totalling 1GW/4GWh, have capacity market contracts (CM), part of a portfolio that Greenvolt won the lion’s share of BESS awards in the 2023 auction, some of which it has sold. The CM and its 17 years of contracted revenue is the bedrock of the business case for large-scale BESS in Poland.
All three projects are also supplied by EV and BESS firm BYD, with the Siedlce deal announced in June.
Just yesterday, we reported on Greenvolt starting construction at a 918MWh BESS in Romania, also alongside other news from across the CEE region.
Gore Street EU fund buys first Polish project
Also in Poland, the investment manager Gore Street Capital’s GS EU Fund SCSp has acquired the 40MW/160MWh Wolborz BESS.
The project also has a CM contract starting in 2030 and will start operations in Q1 2028. The firm didn’t reveal the selling party.
Alicja Kowalewska-Montford, managing director at Gore Street, said: “Our focus now moves to the construction and successful delivery of the Wolborz project, and we are already building relationships with local counterparties, including EPC and other contractors, as we continue to strengthen our presence in Poland.”
The Irish sale between the two Gore Street funds was controversial for some shareholders, who recently pushed for a wind-down and asset sale of the GSF fund because of underperformance. We chatted to GSF’s chair about this, a week before the company narrowly won the vote not to pursue that option (last week).
DS1 starts building 327MWh BESS in Lithuania
Energy infrastructure firm DS1 has signed an EPC agreement and moved to construction on a 140MW/327MWh BESS in Ayltus, Lithuania.
It is building the project in partnership with Israel-headquartered energy services and construction firm BLEnergy, at a new 330kV substation.
The two previously partnered on a 30M/60MWh project in Lithuania, that one supplied by CATL, though it didn’t provide many details on the Ayltus project.
The Baltic region’s energy storage market is currently driven by high ancillary service prices, but increasing durations beyond 1- or 2-hours show a shift towards energy trading and other applications.
Finland-headquartered Taaleri invests in 420MWh Estonia BESS
Finland-headquartered clean energy IPP Taaleri Energia has invested in a 192MW/420MWh BESS in Estonia, via its SolarWind III Fund.
The SolarWind III Fund, a SolarWind III Fund co-investor, and KJK Fund III, a fund managed by KJK Capital, are joint owners of the project.
The construction of the project will start in September 2026, with the BESS expected to be fully operational by November 2027.
The project was developed by developer Evecon and French IPP Corsica Sole (who are also deploying projects to own and operate together in the region).
It will be built by local contractor Smartecon, with the BESS provided by LG Energy Solution and European-made inverters from Power Electronics.
Taaleri has previously deployed projects in its home market of Finland.
