Sizing of Battery Energy Storage System in a Photovoltaic Off-Grid DC Microgrid Incorporating a Lithium-ion Linear Degradation Model

In islanded microgrids, inappropriate battery energy storage system (BESS) sizing can cause power shortage and, without consideration of battery lifetime, increase maintenance costs. Researching best-fit implementations of battery sizing is vital in providing electrification to isolated areas. MATLAB was utilized to determine the battery sizing in a photovoltaic-battery DC off-grid system using a lithiumion degradation model. The system was subjected to various battery and solar array sizes to determine the relationship between sizing and lifetime. Results indicate that the minimum battery size of 22 is appropriate for the system based on the load and solar output to which no blackouts occur with a minimum expected lifetime of 114, 675 hours, or 13.08 years. Furthermore, the correlation between photovoltaics and BESS sizes was observed to ensure maximum battery life and minimal blackouts in off-grid systems. These observations can further sizing application studies, optimal cost research, and islanded DC microgrid potential.