Performance modelling of lead-acid batteries in photovoltaic applications

A test of five lead-acid batteries of four generic types was conducted to determine the effectiveness of an energy storage subsystem model which consists of a lead-acid battery and its associated charge controller used in Sandia´s PV power systems simulation code PVFORM. While PVFORM accurately represented an adequately charged battery operating in a system with little excess array energy, considerable care was required in establishing the model´s user-defined input parameters to describe the more typical performance of a battery when used with a controller that does not maximize the array´s utilization. Causes for this poorer-than-expected battery performance are presented along with their impact on both system design and performance modeling.