Germany Moves Toward 4-Hour Battery Storage – First Flower Projects Mark New Trend in Hamburg and Saxony-Anhalt
Berlin (Germany) – The battery storage market in Germany is increasingly shifting toward larger capacities and longer discharge durations. Key momentum is coming, among others, from Swedish energy technology company Flower Infrastructure Technologies, which is currently developing several large-scale storage projects in the German market.
Hamburg: 4-hour storage system with 400 MWh capacity in Bergedorf
One example of this trend is a 100-megawatt battery storage project with 400 megawatt-hours (MWh) of capacity, which Flower is developing in the Bergedorf district of Hamburg. The new system is designed for a discharge duration of four hours.
Located near the Energy Campus of the Hamburg University of Applied Sciences (HAW Hamburg) and the planned Bergedorf innovation park, the project is intended to support the integration of renewable energy and increase grid flexibility.
Saxony-Anhalt: another large-scale project under development
Another project is being developed in Döllnitz (Saxony-Anhalt). There, Flower is planning a battery storage system with 63 megawatts of power and 257 megawatt-hours of capacity, also designed for a discharge duration of around four hours.
Together, both projects represent 163 MW of power and 657 MWh of storage capacity. They are part of a growing pipeline of large-scale storage projects in Germany that are increasingly designed for multi-hour operation.
Changing role of battery storage – moving toward longer durations
The role of battery storage in the energy system is currently undergoing a fundamental shift. In addition to short-term grid stabilization and frequency regulation, applications such as energy arbitrage, balancing generation fluctuations, and integrating high shares of renewable energy are becoming increasingly important. As a result, requirements for flexibility and especially storage duration are rising.
The trend toward longer durations is considered a structural market shift within the industry. While earlier projects were mainly designed for short-term grid services, battery storage systems are increasingly becoming central components of a flexible power system with growing importance for supply security.
The increasing relevance of longer storage durations is also visible in international technology competition. In Laufenburg, Switzerland, the Technology Center Laufenburg (TZL) is currently developing a large-scale redox flow battery storage system. Depending on discharge capacity, the system can theoretically deliver electricity for more than 20 hours in its final build-out stage, significantly exceeding conventional lithium-ion utility-scale storage systems.
The first phase includes 800 MW of power and 1.6 GWh of capacity, while the final expansion is planned to reach up to 1.2 GW and 2.1 GWh. This makes redox flow technology fundamentally different from conventional battery storage systems, which are typically designed for discharge durations of only a few hours.
German battery storage market on a growth trajectory
The German battery storage market is in a sustained expansion phase. In the first four months (January to April 2026), around 163,000 new battery storage systems with a total installed capacity of 1,470 MW and 2,900 MWh were commissioned (as of May 8, 2026). In the same period last year, the figures were 1,242 MW and 2,060 MWh respectively.
If this trend continues, the International Renewable Energy Agency (IWR) expects installed battery capacity in Germany to exceed 20,000 MW and total storage capacity to reach around 35,000 MWh (35 GWh) by the end of 2026.
Source: IWR Online, 15 May 2026
