The Significance of Considering Battery Service-Lifetime for Correctly Sizing Hybrid PV–Diesel Energy Systems

Abstract

This study emphasizes how crucial it is to consider battery service lifetime when determining the optimal battery size in PV–diesel hybrid systems. It investigates how battery size influences the evaluation of hybrid systems and their lifetime due to battery cycling. Unlike previous research that relies on assumed battery lifetimes, this study delves into the tangible impact of battery cycling, revealing the intricate relationship between battery size, cycling behavior, and service lifetime. Utilizing HOMER Pro version 3.14.2 software, a case study assessed three battery capacities (300 Ah, 800 Ah, and 1000 Ah) in a hybrid PV system catering to a 24 kWh daily demand. Across varying assumed lifetimes (5, 10, and 20 years), the study found that a 300 Ah battery was the most feasible under a 5-year assumed battery lifetime. However, for 10-year and 20-year battery lifetimes, the 800 Ah system emerged as the optimal choice, emphasizing the influence of assumed lifetime on determining the optimal battery size. Throughput battery lifetime analysis estimated service lifetimes of 4.9, 10.96, and 13.64 years for the 300 Ah, 800 Ah, and 1000 Ah batteries, respectively. Notably, smaller-rated batteries exhibited shorter estimated service lifetimes linked to usage patterns. Among the systems assuming a 20-year calendar lifetime, the optimal 800 Ah system, with a service lifetime of 10.96 years, yielded an energy cost of 0.312 USD/kWh, annual costs of USD 2736.5, and a total cost of USD 37,450. Considering service lifetime, the 800 Ah system emerged as optimal, contrasting the initially favored 300 Ah system under a 5-year assumed lifetime. This underscores the crucial significance of comprehending and integrating service lifetime considerations to optimize the economic feasibility of PV hybrid systems.