A study of lead-acid battery efficiency near top-of-charge and the impact on PV system design

Knowledge of the charge efficiency of Pb-acid batteries near top-of-charge is important to the design of small PV power systems. In order to know how much energy is required from the photovoltaic array in order to accomplish the task of meeting load, including periodic full battery charge, a detailed knowledge of the battery charging efficiency as a function of state of charge is required, particularly in the high state-of-charge regime, as PV power systems are typically designed to operate in the upper 20 to 30% of battery state-of-charge. This paper presents the results of a process for determining battery charging efficiency near top-of-charge and discusses the impact of these findings on the design of small PV power systems.