An In-Depth Experimental Investigation of the Outdoor Performance of Wafer and Thin Film Photovoltaics Technologies in a Tropical Climate

Abstract

The photovoltaics (PV) industry is booming at an impressive rate. Knowledge of the outdoor performance of different PV technologies under different climatic conditions is becoming increasingly important for all stakeholders. The aim of this research was to perform the outdoor characterization of three PV technologies in a tropical climate and evaluate their performances with the aid of a set of key performance indicators. An innovative energy autonomous outdoor test facility has been used to measure the weather conditions and the IV curves of mono-Si, poly-Si, and Copper Indium Gallium diSelenide (CIGS) PV modules. Each IV curve was sampled within less than a second, for every 10 min, between sunrise and sunset for a whole year, representing a data set of around 28,000 IV curves of 240 points each. The variations of current, voltage, and power were thoroughly studied for changes in temperature and irradiance. This paper reports the variations of temperature coefficients of current, voltage, and power with the intensity of light. While PV module documentation only presents the temperature coefficients of the short circuit current and open circuit voltage at standard test conditions, this paper additionally provides highly valuable information to PV system designers on the variation of these coefficients in the field. The research is also the first to report the variations of the fill factor with temperature and irradiance. In general, the wafer technologies were found to have a better performance than the thin film technology. Moreover, the open-circuit temperature coefficient was found to improve for higher irradiances only for the wafer technologies, while that for the thin-film technology experienced a degradation. The temperature coefficient of current for the mono-Si module was found to be positive at low irradiance levels, but negative at higher irradiance levels.