Improvement of parameter identification method for the photovoltaic cell

The parameters of photovoltaic (PV) cell may change with the operation conditions. Thus it is important to identify these parameters according to the measured data. In this paper, a four-parameter model was used to describe the PV cell. A method of nonlinear least squares based on stepwise linear search was proposed to identify the parameters of the model. The feasibility of the method was proved by the comparison between the identification curve and the measured data. The results have shown that this method has the advantages of high accuracy and simple realization. Moreover, the three coefficients (α, β and γ) in the model were optimized further. The parameter identification and coefficient optimization (PI-CO) iterative method was proposed through the combination of parameter identification and coefficient optimization. In the iterative process, the values of the parameters and coefficients converged to the optimal points quickly, and the objective function value also decreased gradually, which showed that PI-CO iterative method can further improve the simulation accuracy.