Fluence to supply Leag’s 4 GWh battery project in Germany, Europe’s largest to date

German energy company Leag has partnered with Fluence Energy GmbH, the German subsidiary of US-based Fluence Energy, on a 1 GW / 4 GWh system in Jänschwalde, marking Germany’s first officially announced multi-gigawatt-scale project and arguably Europe’s largest to date.

The GigaBattery project is part of Leag’s GigawattFactory, a major regional-industrial initiative aimed at developing large-scale renewable energy generation, energy storage, and green hydrogen infrastructure in Germany’s Lausitz region, transforming former coal-mining land into a gigawatt-scale green energy hub.

In 2022, the German brown coal miner and power generator announced plans to bring 7 GW of solar and wind capacity online by 2030. By 2023, these ambitions expanded to include up to 14 GW of renewable energy generation, complemented by 2–3 GWh of battery storage and 2 GW of green hydrogen production. Together, these technologies are expected to form a net-zero baseload energy system.

That same year, the first large-scale project under the GigawattFactory initiative was announced at Intersolar Europe in Munich. Leag signed an agreement with NYSE-listed, iron-flow battery specialist ESS to build a 50 MW/500 MWh battery system to help replace the 2.5 MW Boxberg coal-fired power station in Saxony, eastern Germany. Since then, limited updates have been provided on this project and ESS has encountered financial difficulties. With the latest deal, however, Leag is taking a major step forward toward achieving its renewable energy goals.

“With this project, we are igniting another growth engine for our GigawattFactory,” said Adi Roesch, CEO of the LEAG Group. “By constructing gigascale storage facilities, we are addressing one of the biggest challenges of the energy transition: the constant availability of energy regardless of the availability of renewable energies. The key to the energy system of the future lies in a combination of renewable energies, storage facilities that can be used as needed, and flexible power plants.”

According to information provided by Leag to pv magazine, the GigaBattery project is expected to break ground after the completion of the approval process in the second quarter of next year (May/June). Commissioning is tentatively planned for late 2027 or early 2028. Leag has not disclosed the total investment amount for the project but confirmed that the grid connection at the existing power plant site is already in place.

Under the deal, Fluence will supply its latest product, Smartstack, which features an innovative design that facilitates logistics and maintenance, while delivering high energy density. Launched earlier this year, Smartstack is an AC block – a container integrating both the battery and power conversion system (PCS). It uses 314 Ah cells and delivers up to 7.5 MWh of energy storage.

Its patent-pending architecture breaks away from the industry standard 20-foot container splitting the system into two units. One is Smart Skid, which serves as a centralized electrical and control command center, integrating advanced cooling equipment, power control system hardware, all cabling, and comprehensive monitoring capabilities. The second component consits of Pods, which sit atop the Smart Skid and contain the system’s battery cells with integrated sensors. These Pods support cells from multiple vendors and are designed to be swapped with replacement units during maintenance or technology upgrades to maximize system availability.

The collaboration with Fluence encompasses the supply of the battery energy storage systems, the integration of the electrical systems, and the construction of the storage facility. Approximately ten hectares southeast of the Jänschwalde power plant have been designated for the project. Siemens Energy will provide the switchgear required for connection to the 380 kV grid.

“The scale of this project makes it truly special,” says Thomas Brandenburg, managing director of Leag. “The technical design as a four-hour storage system supports the further expansion of renewable energies at the GigawattFactory, helps stabilize the grid, and, thanks to lower specific investment costs, enables optimal utilization of the existing grid connection. We are delighted to have gained Fluence, an experienced technology partner, for the implementation of the GigaBattery Jänschwalde 1000.”