Background, aim, and scope The environmental burden of photovoltaic (PV) solar modules is currently largely determined by the cumulative input of fossil energy used for module production. However, with an increased focus on limiting the emission of CO2 coming from fossil fuels, it is expected that renewable resources, including photovoltaics, may well become more important in producing electricity. A comparison of the environmental impacts of PV modules in case their life cycle is based on the use of PV electricity in contrast to conventional electricity can elucidate potential environmental drawbacks in an early stage of development of a solar-based economy. The goal of this paper is to show for ten impact categories the environmental consequences of replacing fossil electricity with solar electricity into the life cycle of two types of PV modules.