Department of Electric Power Systems, Thai Nguyen University of Technology, Thai Nguyen City, Vietnam

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Abstract: This paper presents a novel approach to complete the mathematical model for photovoltaic system. Corresponding to each type of panel made from semiconductors, the relation between the diode factor and temperature at p-n junction is added into the mathematical model. Using calculation results from the iterative and bisectional technique to determine maximum power point, the system of equations converting some parameters from standard test condition to any working condition, datasheet published by manufacturers, the mathematical model is tested to ensure that the diode factor only depends on temperature at p-n junction. Moreover, the least square method is used to create the function representing this relation from only some pair-values. An experimental control system is designed by combining the proposed mathematical model and a voltage controller in this paper to drive value of voltage at input terminals of a DC/DC buck converter to value of voltage at maximum power point. Experimental results showed the correctness between calculation and datasheet, high accuracy of the proposed mathematical model for any structure of photovoltaic system that helps to simulate the reaction before having actual implementation and harness maximum power from photovoltaic systems.

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