Flywheel hybridization to improve battery life in energy storage systems coupled to RES plants

Abstract The present work investigates the advantages of integrating a hybrid energy storage system in a residential micro-grid, coupled to a PV plant. Specifically, battery hybridization with mechanical flywheel is considered. A suitable code, implementing a dedicated logic of power management, is developed to investigate several design conditions and features, simulating the behavior of both storage devices along one year of operation with 1 min time step. The energy performances of the different micro-grid configurations are presented and discussed. Moreover, based on the simulated yearly trends of the battery state of charge, the effects of flywheel on the battery life are determined resulting in a significant improvement with respect to non-hybrid configurations. In particular, life battery almost triples in the case lead-gel technology is adopted, while the life gain reaches a mean value of 3.6 for lithium-ion battery packs. This result is validated through suitable aging tests on LiFePO 4 cells over three equivalent years of operation.