Investigation of the Performance of Commercial Photovoltaic Modules under Tropical Conditions

The tropical regions will see an increasing share of solar photovoltaic (PV) applications. This paper therefore analyses the irradiance distribution in tropical Singapore and then experimentally determines the dependence of the PV efficiency on irradiance level, for nine different commercially available PV module technologies. For several of the PV module technologies, we also determine the dependence of the temperature coefficient of the modules' maximum power on the irradiance level. A full year of outdoor module testing data in Singapore show that the irradiance distribution has two energy peaks, one at around 400 W$\cdot$m-2and the second at around 850 W$\cdot$m-2. Most PV technologies cannot fully convert the second peak due to the fact that, in Singapore, high light intensities are always associated with higher module temperatures, which in turn reduces the module efficiencies.