Extraction of device parameters from dark current-voltage characteristics of PV devices

Abstract

Solar cells are p-n junction diodes and are prone to parasitic resistances. High series resistances of a few ohms degrade the device performance, as do low shunt resistances. It is therefore necessary to determine these parameters since they are useful in analyzing performance losses. A method to extract these and other device parameters of solar cells from the dark current-voltage (I-V) characteristics is presented in this paper. The following parameters were determined using the proposed method: saturation current, series resistance, shunt resistance and the ideality factor. A program was created to implement the method which utilized the one-diode equivalent circuit model. Curve-fitting was also employed to provide a graphical representation of the results. Evaluation of the method was done using simulated data and actual dark I-V data obtained from monocrystalline and multicrystalline silicon solar cells. The program algorithm is discussed and results are presented. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.