A Single Sensor MPPT Controller for Multi-Channel Photvoltaic Solar Systems

Maximum Power Point Tracking (MPPT) systems sample the output of the Photovoltaic (PV) arrays and apply the proper resistance (load) to obtain the maximum power an PV arrays can provide for any given environmental conditions. For any given set of operational conditions (solar irradiation temperature and total resistance) each PV array has an operating point known as the maximum power point (MMP) wherein the array is working at optimal efficiency. These values correspond to a particular load resistance (characteristic resistance); the characteristic resistance depends on the level of illumination temperature and the age of the cells in the PV array. If the characteristic resistance is lower/higher than the particular characteristic resistance needed to attain MPP then the power drawn from the PV array will be less than the maximum available power that could be drawn resulting in inefficient use of the PV array. Conventional MPPT methods utilize multi-channel PV systems wherein each PV array is relegated 2 channels. These channels are utilized to detect the MPP of the PV arrays. Thus a PV solar system using conventional MPPT systems will have 2N channels each channel having an accompanying MPPT controller/sensor which has its complementary circuitry adding to the cost of fabrication and increase in power consumption/loss as well as increase in circuit complexity. Researchers at the University of Alabama have proposed a MPPT system with a single sensor/MMPT (SS-MPPT) controller that can be used to attain the MPP of each channel and each PV array in the PV solar system. After the sensor senses and collects the necessary values the SS-MPPT controller executes two algorithms in order to maximize power extraction from the PV arrays. By repeating these two algorithms the MPP for each individual channel and thus each PV array can be realized. If any more PV arrays or channels are added to the PV solar system there will be no need for additional controller(s)/sensor(s).