Influencing factors, including rooftop material, ventilation, module framing and other environmental conditions on module temperature of selected photovoltaic (PV) systems in Singapore have been analyzed in detail. The variance of module temperature has turned out to be much larger than the variance of ambient temperature on the different project sites. From the analysis of the influencing factors, guidelines for PV system installations are derived in order to achieve lower module temperatures, eventually leading to an optimized system performance in. tropical regions. (c) 2012 Elsevier Ltd. All rights reserved.