BW ESS has broken ground on what it says is Germany’s largest battery energy storage system (BESS), a 1GW/up to 5.7GWh project at Klostermansfeld in Saxony-Anhalt.
The project, located near the Klostermansfeld substation in the Mansfeld-Südharz region, is also among the largest battery energy storage projects currently under development in Europe. According to BW ESS, the system will be capable of supplying around three million German households with electricity for at least four hours.
BW ESS first invested in the project in 2024 and acquired full ownership earlier this year. The original developer, Zelos Energy Developments, will continue to support the project on local site matters until construction is further advanced towards the end of 2026.
The project is intended to strengthen Germany’s electricity grid by providing additional flexibility and supporting the integration of renewable energy. The Klostermansfeld substation is a major node on the German transmission network and has recently been expanded to transfer greater volumes of electricity from the distribution network onto the high-voltage grid.
Roberto Jiménez, executive director of 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.”
He added: “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.”
The groundbreaking ceremony was attended by Prof. Dr. Armin Willingmann, Saxony-Anhalt’s minister for science, energy, climate protection and the environment and deputy prime minister, and Frank Ochsner, mayor of Klostermansfeld.
Willingmann 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.”
Ochsner 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.”
