BW ESS starts work on landmark German energy storage project
Kelvin Ross
Posted on: 1 July 2026
The 1GW Klostermansfeld project is said to have the capacity to supply around three million homes with electricity for at least four hours.
Swiss energy storage owner-operator BW ESS has broken ground on one of Europe’s largest battery storage projects to date.
The 1GW Klostermansfeld project is in Germany’s Mansfeld-Südharz region in Saxony-Anhalt and is the largest of its kind in the country.
BW ESS claims it has the capacity to supply around three million German households with electricity for at least four hours.
Part of BW Group, BW ESS first invested in the project in 2024 and took full ownership earlier this year. 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 this year.
Energy security
The project is intended to boost energy security and grid stability in Germany. It is located near a Klostermansfeld substation which 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, BW ESS believes its project will strengthen the region structurally and bolster the grid’s ability to cope effectively with peak load periods.
“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,” said Roberto Jiménez, executive director at BW ESS.
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Armin Willingmann, Deputy Prime Minister of Saxony-Anhalt, said the region " 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 battery energy storage systems that help stabilise our power grids. The Klostermansfeld battery energy storage system will be an important building block in this.”
Renewable electricity
“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."
Klostermansfeld mayor Frank Ochsner said the groundbreaking was “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.”
BW ESS is active in the UK, Australia, Italy, Germany, Spain and Sweden, with more than 540MWh of operating battery energy storage systems and around another 11GWh under construction.
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