"The Role of Energy Storage in Germany" focuses on investigating multi-day storage solutions, specifically 100h Iron-Air batteries and their system benefits in Germany 2035. Low-cost Multi-Day Storage (MDS) has great potential to reduce curtailment, flatten electricity prices and reduce resource dependency while helping to meet emissions targets. Its benefits support delays in transmission projects and a mandated phase-out of gas power plants, especially during multi-day dark doldrums. It offers a particularly strong case in extreme weather year scenarios with optimized installed Iron-Air battery capacities of up to 31 GW in Germany. The project GitHub repository includes a fully open and reproducible workflow and comprehensive documentation.