A simple and efficient determination of the ideality factor of solar cells and modules from the knee point of the shunt resistance curve

Abstract

In this work, a simple and efficient method is proposed to determine the ideality factor of solar cells and modules using the knee point of the shunt resistance curve. The method was implemented by deriving a nonlinear empirical equation, which is a function of the shunt resistance and ideality factor, from which a peak value of the function is obtained that corresponds to the knee point of the shunt resistance. Researchers can use this simple approach to efficiently determine the ideality factor by either having the datasheet information or experimental current–voltage (I–V) data. Also, the determined ideality factor can be utilized to extract the other parameters of solar cells/modules, thereby modelling the I–V curve of these devices at different conditions. The method was validated on four different PV modules that are available on the market, namely Poly-Si, Mono-Si, thin film and multijunction (hybrid). It was found that the determination of the ideality factor by applying the proposed approach is easier and more efficient than the methods reported in the literature.