Vattenfall takes a final investment decision on a 254 megawatt battery in Germany. It is not the biggest battery storage project in Germany, but it nearly doubles the battery capacity Vattenfall already runs and is building.

The biggest battery storage project in Germany

Vattenfall took a final investment decision on September 10, 2026, meaning the company committed real money to build rather than just plan a battery at Brunsbuettel, in Schleswig Holstein in northern Germany. It is not the biggest battery storage project in Germany, but it is a major one, built on the grounds of a nuclear power plant Vattenfall owns 67% of, shut down in 2019 and still being taken apart today. Claus Wattendrup, Head of Solar and Batteries at Vattenfall, said the location itself was a strong choice for the project.

The Brunsbuettel site, with its available land and existing grid connection, offers excellent conditions for the construction of the battery storage facility.

Claus Wattendrup, Head of Solar and Batteries at Vattenfall, speaking on why the Brunsbuettel site was chosen. Source 3.

The battery output, the rate it can send power into the grid, will reach 254 megawatts. Its storage capacity, the total energy it can hold before running empty, will be around 1,000 megawatt hours, up from 700 megawatt hours at an earlier planning stage in December 2025, before the final investment decision fixed the design Vattenfall actually built. Dividing those two figures, 1,000 megawatt hours by 254 megawatts, gives about 3.9 hours, the length of time Brunsbuettel could run at full output before it needed to recharge, a calculation Vattenfall itself does not state. At 1,000 megawatt hours, it ranks behind the largest storage projects in Germany. A 1,000 megawatt, 5,700 megawatt hour project called Klostermansfeld, built by a developer named BW ESS in Saxony Anhalt, holds more than 5 times as much energy. The Brunsbuettel battery will connect to the 380 kilovolt grid run by 50Hertz, the company that operates the regional high voltage power lines in that part of Germany. Vattenfall targets commercial operation by the end of 2028.

Vattenfall doubles its own battery capacity

Claus Wattendrup, Head of Solar and Batteries at Vattenfall, said batteries are becoming central to managing the grid.

Batteries play a key role in the future energy system, balancing electricity demand and supply.

Claus Wattendrup, Head of Solar and Batteries at Vattenfall, speaking on the final investment decision. Source 1.

Vattenfall already has 150 megawatts of battery storage in operation and another 120 megawatts under construction, so Brunsbuettel will nearly double the battery capacity the company already runs and is building. Vattenfall has set a target of optimizing up to 1,500 megawatts of battery capacity by 2029, combining batteries it owns itself with services it sells to other battery owners.

A national battery boom

Brunsbuettel is 1 project inside a much bigger national trend. The Bundesverband Solarwirtschaft, the German solar and storage industry trade group, counted around 225,000 new battery storage units installed across Germany in the first 5 months of 2026, adding a combined 3.4 gigawatt hours of capacity, about 70% more than the same months a year earlier, drawing its figures from the German government market registry. Large scale battery storage, systems built to serve the power grid directly rather than a single home, grew even faster. The trade group counted around 1.5 gigawatt hours of large scale battery storage coming online between January and May 2026, more than 4 times the 0.3 gigawatt hours in the same months of 2025.

Transmission system operators across Germany project total battery storage capacity nationwide will pass 80 gigawatts by 2040, a figure Vattenfall cites in the same release announcing the Brunsbuettel decision. The 380 kilovolt grid Brunsbuettel will join, run by 50Hertz, already carries around 75,552 megawatts of total installed generation capacity.