A new approach for parameter estimation of the single-diode model for photovoltaic cells/modules

Bilge Kaan ATAY,Ulaş EMİNOĞLU

doi:10.3906/elk-1805-161

Abstract

Solar energy has become a popular renewable energy source, leading to wide use of photovoltaic (PV) cells/modules in energy production. For this reason, realistic modeling of PVs and determining the equivalent circuit parameters is of great importance in terms of planning and operation. Hence, in this study, an analytical model for identifying the single-diode equivalent circuit parameters; series resistance (Rs ), shunt resistance (Rp ), diode ideality factor (a), diode reverse-saturation current (Io ), and photon current (Ipv ) for PV cells/modules is developed without neglecting any term. In order to test the accuracy of the model, a number of PV modules from different manufacturers are taken into account and the results are compared with those obtained by using such analytical models given in the literature. Current-voltage (I-V ) characteristics of the PV modules, which are studied here, are also simulated by comparing with the experimental I-V curves provided by the manufacturers. Results show that the values of the parameters obtained for the PV modules are consistent with those extracted by using other analytical models. In addition, I-V curves created by using the obtained parameters are in full agreement with the experimental data. The curves also show a high degree of compatibility with the ones created by using the optimal parameters of the two-diode models given in the literature. Moreover, the proposed model provides a great advantage in estimating equivalent circuit parameters in terms of ease of use, requirements for input data, dependency on initial conditions as well as considering the parameters which are neglected in such methods given in the literature.

Highlights

The ever-decreasing production costs of solar panels have made PV modules a preferred energy source to be used in an off-grid or on-grid system
Results show that the value of equivalent circuit parameters do not match each other, but it is quite clear in Figure 3 that the in the literature. Current-voltage (I-V) curve based on the proposed model exactly match the experimental data at all points
An analytical model for extracting unknown parameters of PV cells/modules using the single-diode model was developed without neglecting any of the valuable terms

Summary

Introduction

The ever-decreasing production costs of solar panels have made PV modules a preferred energy source to be used in an off-grid or on-grid system. For the single-diode model, a set of equations were created and solved for different commercial PV cells/modules [7]; the shunt resistor, which is one of the main parameters of the equivalent circuit, was selected as an input parameter. Parameter estimation by using different approaches such as multiple optimization-based method [21], search algorithm based on the reduced form of the equations set [22], hybrid form of the Nelder–Mead and modified PSO algorithm [23], partly search-based method using diode ideality factor ( a ) for the single-diode model [24] and series resistance ( Rs ) for the double-diode model [25] as an independent variable, tool/software solution-based method [26] are available in the literature. Applying Kirchhoff’s current law to the system, we can get the output current as:

Isc Rs

Voc aVt

Na Na Na Na Na

Conclusions