Development of triple-diode based generalized model of photovoltaic module

The growing large-scale penetration of solar power plants into electric grids mandates accurate modeling of the photovoltaic modules with consideration of varying environmental conditions, resulting in the development of a large variety of models at photovoltaic cell, module and array levels.

A novel, scalable triple-diode based equivalent circuit model has been proposed in this paper and implemented on MATLAB/Simulink. This generalized model has the flexibility of representing double and single-diode models, with nine or lesser design parameters, by considering (or neglecting) recombination and diffusion losses, and representing different materials by corresponding values of band gap energy through a customized dialog box. Thus, this generalized model facilitates the implementation of nine different models and has the scalability for representing different photovoltaic plant ratings and flexibility of selecting different photovoltaic materials.

In order to validate the performance of proposed model, a well-known, commercial photovoltaic module has been simulated. The simualtion results validated by comparison with the results reported in the published literature by the most widely referred practical models. The results obtained from all nine variants of the proposed model are at least in close agreement or better than other referred models, when compared at remarkable points with the manufacturer data sheets under standard test conditions, with modeling errors ranging from 0.2 to 7.31%

The scalability of the proposed generalized model is depicted by modeling a 100kW photovoltaic array and validated through practical application of the single diode model to analyze the effect of rise of ambient temperature up to 50 °C, representing hot climatic condition of the site of experimentation, Jodhpur, Rajasthan. The simulation results show that rise in temperature causes significant drop in output voltage in comparison with rise of current of photovoltaic array. Hence, the average output power reduces by 13.26% at maximum temperature. Thus, it is concluded that the proposed model is accurate, scalable and capable of correctly simulating the effect of rise of temperature on the performance of photovoltaic array.