Battery aging in multi-energy microgrid design using mixed integer linear programming

•A linear model for battery degradation is proposed for MILP microgrid sizing.•A case study of PV and storage explores the impact of considering battery aging.•Inclusion of battery aging decreases optimal storage deployment by 6–92%.•For identical PV-storage systems, degradation reduces annual cost savings 5–12%.•Battery health constraints reduce annual battery cycling by as much as factor of 5.