Effect of on/off charge controller on stand-alone PV system performance

Most battery charge controllers in stand-alone photovoltaic power systems shed portions of the PV array in discrete steps as the battery voltage approaches full charge. This paper analyzes the effect of such on/off algorithms on the system performance. A simple analytical model of a multi-step charge controller is presented and illustrated by an example. Computer simulations and field measurements of an actual system show that on/off chargers limit the use of PV energy hence resulting in lower performance than conventional models.