An improved explicit I-V model of a solar cell based on symbolic function and manufacturer's datasheet

This paper proposes a new explicit current-voltage (I-V) modeling approach for the single-diode model of solar cells. The authors presented in a recent work a method to obtain an explicit I-V characteristic model based on Taylor's series expansion. This method use Taylor's series expansion to directly express the exponential function term of I-V characteristic equation and then an explicit I-V model is proposed. However, the approximation error of the method is becoming larger in the vicinity of the maximum power point, especially in high irradiance. Therefore, an improved explicit I-V model is constructed by using symbolic function and manufacture's datasheet in this paper. Firstly, the exponential function term of I-V characteristic equation is decomposed into the product of two functions in this paper. One of the two functions is a exponential function with current at maximum power point. The other is a exponential function with symbolic function. The values of symbolic function are determined by open-circuit voltage, short-circuit current, the ideality factor and total absorbed irradiance. Secondly, Taylor's series expansion is used to express the exponential function with symbolic function. Thus, an explicit analytical description of current I, named Taylor Model based on Symbolic Function (TMSF), is obtained. Finally, to validate the effectiveness of the method proposed in the paper, three types of silicon modules with different technology are tested at different weather conditions. Experiment results show that the proposed modeling method greatly improves the approximation error of the model based on Taylor's series expansion, especially in the vicinity of the maximum power point.