A Simple Technique for Evaluating the Performance of Grid Connected Inverters

One of the challenges associated with evaluating the reliability of a large number of grid-connected (GC) photovoltaic (PV) systems is the expense of the measurement and data logging equipment required to measure typical operating parameters for these system. In order to fully monitor a PV system, it is necessary to measure plane of array solar irradiance, solar spectrum, array temperature, DC voltage, and DC current as well as the AC voltage, AC current, and AC power produced by the inverter. This paper presents a technique for evaluating several aspects of the performance and reliability of a grid-connected PV system using just one AC power meter / data logger to record the minimum, maximum, and mean power produced by the system over small segments of time. The data can then be graphed to quickly identify a wide variety of inverter problems, several examples of which are presented.