This paper presents an evaluation of the performance degradation of Photovoltaic modules after few operation years in a tropical environment. To this end, the International Center for Research and Training in solar energy at Dakar University and the Lasquo-ISTIA laboratory of Angers University have put in place a research project in order to investigate the impact of the tropical climatic conditions on the PV modules characteristics. Accordingly, two monocrystalline-silicon (mc-Si) PV modules and two polycrystalline- silicon (pc-Si) PV modules are installed at Dakar in Senegal and monitored during a few operation years: Module A (16 months), Module B (41 months), Module C (48 months) and Module D (48 months). After few operation years under tropical environment, the global degradation and the degradation rate of electrical characteristics such as I-V and P-V curves, open-circuit voltage (Voc), short-circuit current (Isc), maximum ouput current (Imax), maximum output voltage (Vmax), maximum power output (Pmax) and fill factor (FF) are evaluate at standard test conditions (STC). This study reports on data collected from 4 distinct mono- and poly-crystalline modules deployed at Dakar University in Senegal. The study has shown that Pmax, Imax, Isc and FF are the most degraded performance characteristics for all PV modules. The maximum power output (Pmax) presents the highest loss that can be from 0.22%/year to 2.96%/year. However, the open-circuit voltage (Voc) is not degraded after these few exposition years for all studied PV modules.