A 103.5 MW/238 MWh BESS in Bollingstedt, Germany, is being acquired by Alpiq from ECO STOR. The facility has operated since June 2025 and will become Alpiq's first operational large-scale BESS in Germany and its third operational battery storage asset overall.
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Alpiq, a Swiss energy company, is acquiring BESS Bollingstedt from ECO STOR, adding a 103.5 MW/238 MWh operational BESS in Schleswig-Holstein, Germany, to its portfolio. ECO STOR, a German-Norwegian company has developed and built the facility, has later commissioned in 2025 and has been in operation since June 2025.
The acquisition gives Alpiq its first operational large-scale BESS in Germany. Bollingstedt will become the company's third operational BESS and its largest by output. Alpiq's other operational assets are BESS Cheviré in France, with 100 MW, and BESS Valkeakoski in Finland, with 30 MW. Further BESS projects with more than 250 MW of combined installed capacity are under construction or close to commissioning, and the remaining projects in Italy and Switzerland are in development.
Earlier in July 2026, Alpiq has acquired a 90% majority stake in Harmony Energy, a pan-European developer and operator of BESS with a multi-gigawatt project pipeline in the UK, France, Germany and Poland. Alpiq has said that the BESS Bollingstedt complements that pipeline with an operational asset that contributes directly to earnings and gives the company direct access to the German battery storage market. Amédée Murisier, Head of the Assets business division and a member of Alpiq's Executive Board, said that the company would also evaluate further opportunities involving operational battery storage systems in Germany.
The companies have agreed not to disclose the financial terms of the transaction. The transaction extends an existing relationship between Alpiq and ECO STOR. In November 2025, the companies signed a long-term tolling agreement for the Schuby BESS in northern Germany, which ECO STOR built and operates. Alpiq stated has that the BESS and pumped-storage hydropower plants support renewable energy integration and help balance electricity supply and demand, while also supporting electricity-system resilience and security of supply.