RWE begins construction of Germany’s largest battery storage facility

RWE has started building Germany’s largest battery energy storage facility at its Gundremmingen site in Bavaria, marking a major step in the company’s plan to repurpose former nuclear power sites for renewable energy use. The 400MW facility, with a total storage capacity of 700MWh, will use the existing grid infrastructure of the decommissioned Gundremmingen nuclear plant.

The project represents an investment of about €230 million ($266.98 million) and is designed to balance Germany’s renewable-heavy grid by storing excess solar and wind power and supplying it during periods of low generation. Alongside the storage system, RWE plans to develop a 55-hectare solar park expected to generate up to 70 million kWh annually. A gas-fired peaking plant will also be built to provide backup power during high demand or low renewable output.

The groundbreaking ceremony was attended by Bavarian Minister-President Markus Söder and RWE CEO Markus Krebber. The facility will include over 200 containers housing approximately 850,000 lithium-iron phosphate battery cells and will use more than 100 ultra-fast inverters for rapid response. This will allow the system to inject or absorb electricity within milliseconds, supporting grid stability.

Commercial operations are expected to begin in early 2028. Once operational, the Gundremmingen storage plant will be able to supply 400MW of electricity continuously for nearly two hours. According to RWE, the project reflects its strategy to expand its battery storage portfolio and reuse existing energy sites to support Germany’s energy transition.