BW ESS, the global energy storage owner-operator, has broken ground on one of Europe’s largest battery energy storage (BESS) projects to date, the 1000 MW/up to 5700 MWh Klostermansfeld BESS.

Located in the Mansfeld-Südharz region, Saxony-Anhalt, in close proximity to the Klostermansfeld substation, the project is the largest of its kind in Germany. It has the capacity to supply around 3 million German households with electricity for at least four hours.

BW ESS first invested in the project in 2024 and took full ownership earlier in 2026. The initial developer and seller, Zelos Energy Developments, will continue to provide targeted support on local site matters until the project is further into construction, at the end of the year.

As an experienced long-term owner-operator, BW ESS maintains direct oversight of its assets throughout their operational lifetime, taking a hands-on approach to unlock value throughout the energy storage asset lifecycle.

The project will become a major contributor to energy security and grid stability in Germany. Klostermansfeld substation functions as one of few central nodes on the German energy grid and has recently been expanded to draw more electricity from the distribution grid and transport it via high voltage power lines. As such, Klostermansfeld BESS will strengthen the region structurally and bolster the grid’s ability to cope effectively with peak load periods.

Roberto Jiménez, Executive Director, BW ESS, responded: “At BW ESS, we’re proud that our work in energy storage contributes directly to a resilient modern energy system. We’ve made a long-term commitment to help realise the potential of energy storage in Germany and Klostermansfeld BESS will be our first German asset to enter construction. We will continue to take an active approach to knowledge transfer across our portfolio, leveraging our extensive experience from the mature global markets.”

Prof. Dr. Armin Willingmann, Minister for Science, Energy, Climate Protection and the Environment and Deputy Prime Minister of Saxony-Anhalt, commented: “Saxony –Anhalt is one of the pioneers in the energy transition, especially in the expansion of renewables. It is therefore important for our?state?to have grid-serving BESS that help stabilise our power grids. The Klostermansfeld BESS will be an important building block in this.?Increasing?volumes?of renewable electricity can be absorbed by the large scale storage system and then transported further via the grid. With?this?system here at the site, BW ESS is helping to secure?supply and ensure more flexibility in the power grid.”

Frank Ochsner, Mayor of Klostermansfeld, added: “This ground-breaking is a significant day for our community, officially marking the location of Germany’s largest battery storage facility, right here in Klostermansfeld. We are delighted about this major investment and the operator’s commitment to contribute further, both financially and through their expertise. The community and the regional economy will benefit greatly from this.”