A new explicit double-diode modeling method based on Lambert W-function for photovoltaic arrays

Abstract

This paper proposes a new explicit double-diode modeling method based on Lambert W-function (EDDMMLW) for solar cells and photovoltaic (PV) arrays with bypass diodes, respectively. There are mainly two kinds of models for solar cells: single-diode model and double-diode model. Since the two kinds of models are implicit and nonlinear, they are usually needed to converted into explicit expressions. Many explicit expressions of I–V characteristic for single-diode model have been proposed. However, explicit expressions of I–V characteristic for double-diode model are rarely found in the current literature. This paper utilizes Lambert W-function to model explicit expressions of I–V characteristic for double-diode model. Firstly, Lambert W-function is used to obtain an explicit double-diode modeling method for solar cells. Secondly, in order to make the method suitable for solar cells with shading, we propose a new explicit double-diode modeling method for PV arrays with bypass diodes. In addition, this paper presents a new explicit expression for series resistance by using EDDMMLW for solar cells in this paper. It is worth mentioning that the seven cell parameters of double-diode model can be obtained by only using four electrical parameters, i.e., voltage and current at maximum power point, open circuit voltage and short circuit current. Finally, we select MSX-60 module, KC200GT module and SM55 PV array to validate the accuracy and simulation speed of the method proposed in this paper. Simulation results show that the method proposed in this paper is accurate and fast for solar cells and PV arrays with bypass diodes at any conditions.