A passive MPPT technique for grid-connected photovoltaic systems

One way to minimize costs of photovoltaic (PV) systems is that of maximizing their energy production, per kW of installed power and for a fixed solar irradiation (SI) and temperature. For this reason, in the specialized literature, a great attention has been devoted to researches on efficient techniques able to continuously track the maximum power point (MPP) of the photovoltaic generator (PG). In the paper, a low cost passive technique is introduced for gridconnected photovoltaic systems. The technique is based on a well known resource, already utilized and fundamental in stand-alone photovoltaic systems: the battery. In fact, a proper selected number of batteries to be put in parallel to a same number o PV sub-fields of the whole PV plant, if properly designed in their nominal voltage and in their capacity, seems able to “intrinsically” and continuously track the maximum power point of the grid connected PG, especially in case of non uniform solar irradiation (SI) conditions. In order to show the usefulness of the proposed technique, the results of a lot of measurements on a small power prototype are reported and critically analyzed.