Experimental evaluation of hardware-based Global Maximum Power Point Searching methods

Operation under partial shading condition (PSC) significantly decreases energy extracted from photovoltaic (PV) power plants. Non-uniform insolation caused by the passing clouds and natural obstacles results in some PV modules to be effectively excluded from operation. Commercially used maximum power point tracking (MPPT) algorithms do not have any information about the global behavior of the PV string or array which they control. This can induce significant error in determining the optimum operating point and in turn affect efficiency of the system. This paper focuses on Global Maximum Power Point Searching (GMPPS) methods based on fast, hardware power-voltage (p-v) sweeping techniques. Two methods based on variable channel resistance of the MOSFET and switched inductor are analyzed and tested for a 3.5 kW PV array in the field conditions. Study shows that both solutions are suitable for accurate p-v sweep independently of the PV array configuration or shading pattern.