With the increasing energy demand and in order to mitigate the impact of climate change, PV system technologies are growing rapidly among alternatives sources of energy. According to previous studies, PV system efficiency depends on geographical location because solar radiation varies according to latitude. It depends also to the position at which the PV panel is set (tilted or horizontal), and the local meteorological conditions (temperature, humidity, dust). Researches about the efficiency of PV system operating under weather conditions in West Africa are nascent. The principal objective of this research is to determine the sensitivity of Photovoltaic (PV) efficiency to meteorological parameters (temperature, humidity) in different climate conditions (Niamey and Abidjan) and how the change in the climate may impact the future of PV system. The second objective is to quantify the effect of dust accumulation on PV efficiency in Niamey. These objectives are achieved by doing experiments for two orientations of PV panel: the horizontal and the tilt to the latitude of the considered site and analysis of future climate scenario using simulation. The results show that increasing humidity in both studies areas (Niamey and Abidjan) induces a decrease of PV efficiency and high temperatures (above 33 °C) decrease PV efficiency. PV efficiency is higher when it is tilted to the latitude of the site (average efficiency = 7.38%) than set horizontally (average efficiency = 7.15%). As far as climate change is concerned, simulation shows that temperature will increase significantly whenever humidity remains quite constant (slight decrease less than 2%) by the end of the century (2100). For the dust accumulation, result shows that power loss of PV goes up to 12.46% after 21 days of dust accumulation over Niamey.