This paper deals with the temperature impact on the IV curve of concentrator photovoltaic (CPV) modules equipped with III–V triple-junction solar cells. The electrical parameters of three FLATCON® type CPV modules are investigated using a sun simulator, where the module temperatures are varied by heating with infrared (IR) bulbs. It is found that all electrical parameters vary linearly to a change of temperature. The open circuit voltages and the fill factors (FFs) of the CPV modules decrease with increasing temperature. The relative decrease in open circuit voltage of the CPV modules is similar to the value of individual triple-junction solar cells. In contrast, the short circuit current temperature coefficients are found to be different. The experimental results can be explained by considering thermal expansion effects in the module and temperature dependencies of the optical efficiencies of the Fresnel lenses. Copyright © 2010 John Wiley & Sons, Ltd.