Battery storage system with a capacity of over 100 MW now officially connected to the grid

05.06.2025

Source: E & M powernews

A battery storage facility with an output of 103.5 MW and a storage capacity of 238 MWh has been in operation in Bollingstedt, Schleswig-Holstein, since April. The minister paid a visit to the opening ceremony.

The German-Norwegian energy storage manufacturer Eco Stor, based in Bad Homburg, and the project developer EPW GmbH (Bonn), which specializes in large-scale battery storage, have built what they claim is "the largest battery storage facility in Germany". The "Eco Power 1" plant with an output of 103.5 MW and a capacity of 238 MWh has been in operation in Bollingstedt, Schleswig-Holstein, since April. It was officially opened on June 5 by Schleswig-Holstein's Environment Minister Tobias Goldschmidt (Green Party).

The storage facility is located on an area of around 1.2 hectares in the immediate vicinity of a transformer station. According to the operator, the facility consists of 64 containers with lithium-ion batteries and 32 containers for inverters and transformers. The stored electricity comes from surpluses from wind power and photovoltaic systems.

At peak times, the energy is fed into the power grid of the local operator SH Netz. According to Eco Stor, the battery could supply around 170,000 multi-person households with renewable electricity for two hours at a time. Eco Stor and EPW are currently building a second battery storage facility of a similar size with a capacity of around 100 MW in the neighboring municipality of Schuby.

The operation of the storage facility is based on the day-ahead and intraday prices on the wholesale electricity market in real time. The system is also used to provide primary and secondary control power. A specially developed digital grid twin from Eco Stor continuously analyzes grid conditions and calculates signals "when it is unfavorable to feed into or withdraw from the grid - and acts in the interests of the general welfare of the grid and system".

Environment Minister Goldschmidt said at the opening of the facility: "Storage facilities also increase the attractiveness of the business location and increase the income of local authorities, which benefit from trade taxes. So everyone benefits". Eco Stor Managing Director Georg Gallmetzer added: "We are proving that the energy transition can be achieved with private investment and without state subsidies."

According to Eco Stor, it sees itself as the "only player in Germany" that covers the entire value chain from the design and construction to the operation of battery storage systems. The company is backed by an international consortium with the project developer X-Elio, which specializes in renewables, the investment company Nature Infrastructure Capital and the Norwegian energy supplier A Energi.

Author: Stefan Sagmeister