Environmental performances of PV systems are likely to evolve in the future due to significant technological improvements of the systems, to less energy intensive manufacturing processes as well as a shift towards less carbon-intensive energies for electricity mix. In spite of the complexity to estimate these changes with accuracy, projections are available based on scenarios representing different levels of improvements. Based on these scenarios, prospective environmental impacts and electricity production of large scale PV systems are assessed. This paper focuses on GHG performance of large scale photovoltaic ground mounted systems based on the Cadmium Telluride (CdTe) technology. We compare the current (2011-2013) and prospective (at 2050 time horizon) GHG performance of such PV systems under different scenarios accounting for technological improvements, future electricity mixes, and module manufacturing origin. A significant decrease in GHG performance is to be found for the prospective scenarios compared to the current situation ranging from 50 up to 80% depending on the scenarios. Prospective technological improvement seems to induce more uncertainties than prospective electricity mixes involved in manufacturing the modules.