SMA Altenso strengthens grid stability with large-scale battery storage system for RheinEnergie
July, 2026—SMA Altenso has successfully commissioned a utility-scale battery storage system for the Cologne-based energy supplier RheinEnergie AG. The project in Einbeck, Lower Saxony, is now fully operational and constributes directly to grid stability, increased efficiency in the energy system, and the security of electricity supply at a key node of the German power grid.
Key hub in the north–south power flow: Battery storage optimizes grid operation
The battery energy storage system (BESS) is located in a region that plays a central role in the north–south power flow, between high feed-in volumes from wind energy in northern Germany and major consumers in the south. By temporarily storing surplus energy and feeding it into the grid as required, the battery storage system helps reduce grid bottlenecks, minimize curtailment, and enable more efficient use of renewable energy.
"For us, battery energy storage systems are far more than standalone infrastructure projects. They represent a key growth area for RheinEnergie and an essential pillar of our strategy to build scalable energy services across Germany. With every new project, we expand our portfolio, strengthen our expertise in the flexibility markets, and lay the foundation for continued growth beyond our core region. The Einbeck project marks another important milestone on this journey. For the commercial optimization of the asset, we rely on the expertise of our trading subsidiary, RheinEnergie Trading, which brings many years of experience in the energy markets."
Stephan SegbersMember of the Executive Board, RheinEnergie"This project is particularly special to us. We have supported the battery storage system throughout its entire lifecycle, from development and permitting to turnkey delivery, and we will continue to support its long-term operation. At the same time, this project perfectly reflects what Altenso stands for: project development expertise, excellence in execution, and technological leadership. Equally important is our partnership with RheinEnergie. The energy transition cannot be achieved by individual players acting alone. It succeeds when companies bring together complementary capabilities and take responsibility together. That is exactly what RheinEnergie and Altenso have done in Einbeck, and it is why I am confident that this project will be followed by many more as part of our ongoing collaboration.”
Burkhard SoehngenManaging Director, SMA Altenso
Performance capability and system services of the battery storage system
With a usable capacity of 24.5 MW / 64 MWh, the BESS provides system-relevant services for frequency and grid stabilization. These include, in particular the provision of primary control reserve (PCR) and secondary control reserve (SCR). At the same time, the system is flexibly deployed for both grid services and participation in day-ahead and intraday electricity markets. In addition, the storage system can supply reactive power when required, thereby supporting voltage stability in the grid.
The solution is based on SMA’s inverter and control technology and enables flexible operation across various market and grid requirements. The technical scope of supply includes 8 medium-voltage power stations (MVPS) equipped with SMA Sunny Central Storage UP inverters, as well as 16 battery containers. The inverters combine high performance, operational reliability, and efficiency while fully complying with applicable cybersecurity standards.
Operation and long-term partnership
As part of the project, Altenso assumed overall responsibility as the EPC partner for the planning, engineering, and construction of the so-called “Battery Park Einbeck.” This also included the implementation of the medium-voltage grid connection, including switchgear and associated cable infrastructure. Beyond commissioning, Altenso remains closely involved and continues to provide operations and maintenance (O&M) services for the Einbeck site.
The project also creates significant added value for the region. It contributes to security of supply and supports the integration of renewable energy. The Battery Park Einbeck underlines the central role of modern battery storage systems as a flexibility option in the energy system. The combination of market integration, system services, and active grid support makes them a key element for a stable and increasingly renewable electricity system.