Methods for sizing both vented and valve-regulated lead-acid batteries used with terrestrial photovoltaic (PV) systems are described. The purpose of this document is to assist system designers in sizing batteries for residential, commercial, and industrial PV systems. Iterative techniques to optimize battery costs, installation, maintenance, safety, testing procedures and consideration of battery types other than lead-acid, are beyond the scope of this document. Recommended practices for the remainder of the electrical systems associated with PV installations are also beyond the scope of this document.

This Recommended Practice describes methods for sizing both vented and valve regulated lead-acid batteries used with terrestrial photovoltaic (PV) systems. Installation, maintenance, safety, testing procedures, and consideration of battery types other than lead-acid, are beyond the scope of this document. Recommended practices for the remainder of the electrical systems associated with PV installations are also beyond the scope of this document. The purpose of this Recommended Practice is to assist system designers in sizing batteries for residential, commercial, and industrial PV systems. Sizing examples are given for various representative system applications. Iterative techniques to optimize battery costs, which include consideration of the interrelationship between battery size, PV array size, and weather, are beyond the scope of this document.