Investigation of the Performance of CIS Photovoltaic Modules under Different Environmental Conditions

Abstract

This work investigates the effects of temperature and radiation intensity on the parameters of a copper indium diselenide (CIS) photovoltaic module. The module performance parameters are determined from calculated module parameters. An outdoor experimental setup is installed to carryout a series of I-V curve measurements under different irradiance and temperature conditions for the module. A numerical model which considers the effect of series and shunt resistances is developed to evaluate the different parameters of PV modules. Orthogonal distance regression (ODR) algorithm is adapted for fitting I-V measurements and extracting module parameters from I-V measurements. The values of module parameters, series resistance Rs, shunt resistance Rsh, diode ideality factor n and reverse saturation current Io determined from I-V measurements at different irradiation intensity and temperature range are in good agreement with the corresponding parameters obtained from the developed numerical model. The module parameters extracted from I-V measurements are employed to calculate the module performance parameters, i.e. open circuit voltage Voc, fill factor FF and module efficiency η at different irradiation intensity and temperature range. Present results indicate that the largest drop in open circuit voltage Voc due to about 20℃ increase in temperature is approximately 8.8% which is not compensated for by the relatively small increase in short circuit current, (2.9% in Isc), resulting in a reduction in maximum power of about 6.3%. Results let us conclude that the shunt resistance RSh increases with radiation at low radiation values (2). As radiation increases at high radiation values (> 400 W/m2), RSh begins to decease sharply and dramatically. Also, as the light intensity incident on the solar module increases, the series resistance and the output voltage decrease. When the irradiance intensity increases, the series resistance decreases but with a very low rate at the two studied temperatures ranges. The low rate decrease of Rs is found to have little effect on module performance in comparison with the significant change of other module parameters. The ideality factor n and saturation current Io decrease first sharply in the low range of radiation intensity (2) and this decrease becomes smaller for irradiance values greater than 400 W/m2. The previous observations and conclusions regarding the module parameters RSh, RS, n and Io obtained at 20℃ observed again at 40℃ but there is a great difference between the peak values of RSh at both temperature levels. Present results also show that module efficiency decreases with increasing irradiance intensity due to the combined effect of both Voc and FF.