Authors have evaluated the life cycle of a thin-film CdS/CdTe PV module to estimate the energy payback time (EPT) and the life-cycle CO2 emissions of a residential rooftop PV system using the CdS/CdTe PV modules. The primary energy requirement for producing 1 m(2) of the CdS/CdTe PV module was similar to a-Si PV module at annual production scale of 100 MW. EPT was calculated at 1.7-1.1yr, which was much shorter than the lifetime of the PV system and similar to that of a-Si PV modules. The life-cycle CO2 emissions were also estimated at 14-9 g-C/kWh, which was less than that of electricity generated by utility companies. (C) 2001 Published by Elsevier Science B.V. All rights reserved.