- The 1GW/up to 5.7GWh Klostermansfeld Battery Energy Storage System – now 100% owned by BW ESS – is the largest BESS project in Germany
- Groundbreaking ceremony attended by Saxony-Anhalt Energy Minister and Mayor of Klostermansfeld
Saxony-Anhalt, 1 July 2026 — Today BW ESS, the global energy storage owner-operator, breaks ground on one of Europe’s largest battery energy storage projects to date, the 1,000MW / up to 5,700MWh 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 three million German households with electricity for at least four hours.
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 2026.
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, said: “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.”
“We thank our development partner, Zelos, for their work on the project and are especially grateful to Minister Prof. Dr. Armin Willingmann and Mayor Frank Ochsner for joining us to mark the occasion.”
Prof. Dr. Armin Willingmann, Minister for Science, Energy, Climate Protection and the Environment and Deputy Prime Minister of Saxony-Anhalt, said: "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 battery energy storage systems that help stabilise our power grids. The Klostermansfeld battery energy storage system 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 groundbreaking 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.”
About BW ESS
BW ESS is a global energy storage owner-operator, moving with speed to develop, deliver and operate market-leading projects.
The business is active in the UK, Australia, Italy, Germany, Spain, and Sweden. It has more than 540MWh of operating Battery Energy Storage Systems (BESS), with ~11GWh under construction and a development pipeline of several gigawatts.
Part of BW Group, BW ESS builds on decades of global infrastructure experience, takes a long-term view of projects and partnerships, and focuses on unlocking value throughout the energy storage asset lifecycle.
To find out more, visit: https://bw-ess.com/
Media contacts:
Tamarindo Communications
bwess@tamarindo.global
