ResHy – Resource-Saving Hybrid Battery - Construction, Integration and Operational Optimization

The objectives of the ResHy project are the development of a system solution for the integration of a hybrid energy storage system into  a PV Power Plant and its operational optimization. This hybrid storage system will consist of a sodium-sulfur battery system (NaS) and a "2nd-life" lithium-ion battery system (LiB), consisting of used vehicle batteries, and will be implemented in a PV Power Plant with approx. 50 MWp planned by EnBW AG near Gundelsheim (BW). The performance and aging behavior of the two battery technologies will be investigated in detail under real operating conditions. These results will be used to optimize the operation management strategies of the innovative energy management system developed in this project. 

Stationary energy storage systems are becoming increasingly important due to the increased use of fluctuating renewable energies. From an ecological and economic point of view, it makes sense to build battery storage systems from sustainable materials as far as possible and to use conventional batteries for as long as possible. 

By combining a sodium-sulfur battery (NaS) and a lithium-ion battery (LiB), consisting of used vehicle batteries, to form a hybrid storage system, the ResHy project is making a significant contribution to the sustainability and longest possible useful life of energy storage systems. The sodium-sulfur battery will be used to provide large amounts of energy, and the lithium-ion battery will be used to provide  high power at short notice.

In the project, the battery systems are first characterized electrically and thermally and their aging behavior is analyzed. In addition, aging models will be developed for both technologies and validated using field data. On the basis of these models, service life forecasts can be made and the performance and aging behavior can be optimized through adapted operational management.

An innovative energy management system (EMS) with optimized operation management strategies adapted to the two battery technologies is being developed for the integration of the hybrid storage in PV ground-mounted systems. This EMS uses the developed battery models as a "digital twin" for both storage systems and is also able to adapt operating parameters to changing system conditions.

Within the scope of this project, the hybrid storage system will be implemented in a projected PV Power Plant of EnBW AG near Gundelsheim (BW) with approx. 50 MWp.

During the demonstration phase, essential knowledge regarding the functionality of the developed energy management system as well as the system behavior of the hybrid storage and the aging behavior of the used battery technologies under real operating conditions shall be gained. The "predictive maintenance" functionality of the energy management system will enable technical problems to be detected on time and allow storage components to be replaced before they fail.

In addition, a life cycle analysis for the hybrid storage concept and the battery technologies used will be carried out as part of this project.