Alpiq adds major German battery storage system to its portfolio

Lausanne – Alpiq is making a further strategic investment in flexible energy infrastructure: the Swiss energy company is acquiring from ECO STOR one of Germany’s largest operational battery energy storage systems (BESS). The 103.5 MW facility in Bollingstedt, in the federal state of Schleswig-Holstein, was developed and built by the German-Norwegian company and commissioned in 2025. The acquisition strengthens Alpiq’s flexibility portfolio and complements its BESS project pipeline.

With the acquisition of BESS Bollingstedt, Alpiq is taking another step in the implementation of its growth strategy. The transaction expands its infrastructure portfolio with its first operational large-scale battery storage system in Germany, one of Europe’s most important markets for flexibility solutions. The facility in Schleswig-Holstein has been in operation since June 2025 and, with an output of 103.5 MW and a storage capacity of 238 MWh, is one of the largest battery storage systems in the country. Alpiq and ECO STOR have agreed not to disclose the financial terms of the transaction.

“With BESS Bollingstedt, we are strengthening our ability to provide flexibility where it delivers the greatest value for the electricity system,” says Amédée Murisier, Head of the Assets business division and member of Alpiq’s Executive Board. “The facility is an excellent fit with our existing portfolio and underlines our ambition to take a leading role in the European battery storage market. Alongside our existing project pipeline, we will therefore also explore further opportunities in Germany involving battery storage systems that are already operational.”

Flexible energy storage assets such as BESS and pumped-storage hydropower plants are essential to the energy system of the future. They support the integration of renewable energy and help balance electricity supply and demand. In doing so, they strengthen the resilience of the electricity system, increase security of supply and play a key role in enabling the energy transition.

Third operational BESS in Alpiq’s portfolio

Bollingstedt is the third and currently largest operational battery storage system in Alpiq’s portfolio. The other two are BESS Cheviré (Nantes Saint-Nazaire, 100 MW) in France and BESS Valkeakoski (30 MW) in Finland. Further BESS projects with a combined capacity of more than 250 MW are currently under construction or close to commissioning. In addition, projects in Italy and Switzerland are in the development phase.

In early July, Alpiq acquired a 90 per cent majority stake in Harmony Energy, an established pan-European developer and operator of BESS with a multi-gigawatt project pipeline in the United Kingdom, France, Germany and Poland. The acquisition of BESS Bollingstedt complements this pipeline with an operational asset that contributes directly to earnings and gives Alpiq direct access to the German battery storage market.

By combining a strong project portfolio with operational assets, Alpiq is strengthening its position along the battery storage value chain and laying the foundations for the further expansion of its flexibility platform in Europe.

Renewed collaboration with ECO STOR

Alpiq already has an established partnership with ECO STOR, a German-Norwegian company that develops, builds and operates battery storage systems in Germany. In November 2025, the two companies signed a long-term tolling agreement for the Schuby battery storage system in northern Germany, which was also built and is operated by ECO STOR. The acquisition of BESS Bollingstedt reflects Alpiq’s confidence in ECO STOR’s project development capabilities, technical expertise and understanding of economically viable storage solutions. It also underlines the two companies’ shared conviction that high-performance battery storage systems are an important component of a sustainable energy system.

Further information on Alpiq can be found at www.alpiq.com.

Photo: Ulrich Mertens