A hybrid algorithmic method for evaluating the solar cell model parameters

Abstract

In this paper, we study the equivalent circuit model and model parameter extraction method for the solar cells in order to provide a precise model for the photovoltaic system simulation. Based on analytical and numerical methods, we propose a new hybrid approach to extract the model parameters from I-V features of solar cells. The experimental result shows that this method is simple and efficient for solar cell modeling. There are several kinds of equivalent circuit models for solar cells, from simple to complex, with different parameters to be considered. However, the actual equivalent circuit model is commonly used in engineering applications to represent the solar cell I-V characteristics. There are 5 parameters in the actual equivalent circuit model, and they are IPH, ISAT, α, RS, and RP. Since the accuracy of the model depends to a certain extent on the accuracy of the model parameters, the extraction of parameters for the equivalent circuit model is necessary and meaningful. And this work is also a common concern for many researchers and engineers focused in photovoltaic systems. According to the existing literature, there are few studies on solar cell module models. The analytical methods and numerical methods are the traditional ways to extract parameters, but sometimes they are unable to give an accuracy result easily. As a result, the hybrid method is proposed in this paper which is a reasonable combination of numerical and analytical methodologies. The basic idea of this method is to do a sensitivity analysis of each parameter firstly, then classify the parameters into two categories: redundant parameters and non-redundant parameters. We can obtain the results of non-redundant parameters by curve fitting, and use them as the initial conditions to build a system of analytical equations to solve the redundant parameters. In this paper, we present an example of a real equivalent circuit model of a solar cell to illustrate the procedure of the hybrid method and we experimentally demonstrate the validity of the equivalent circuit model based on this method.