Owing to the finite supply of fossil fuels and the negative public opinion surrounding nuclear energy, alternative energy resources are the subject of considerable research on a global scale. Thermal solar energy seems to be the most promising one but remains relatively expensive. To reduce the cost, we have interest in substituting copper circuit by a low-cost material. Conductive Polymer Composites (CPC) [1] seem to be a good candidate for such application but their resistance to ageing still not yet proved. The purpose of this study was to elaborate a conductive polymer composite (CPC) that could be used in a thermal solar panel. To achieve this goal, we choose to use bio-sourced polymers like polylactic acid (PLA) and polyamide 12 (PA12), which were filled with Multiwall carbon nanotube (CNT) [2] and Graphite [3]. In this work, the degradation of polylactic acid (PLA) and Polyamide 12 (PA12) nanocomposites under natural and artificial weathering was investigated as a function of fillers loadings for different exposure period. The Attenuated Total Reflection Infra-Red Spectroscopy (ATR-IR) was used to show up the photo-oxidation mechanism on CPC and the effect of fillers type and loading on it. Furthermore, the chemical mechanisms responsible for the formation of new chemical groups were identified. Also, electrical resistivity was investigated to check the ageing effect on the network structure. The thermal degradation of the different composites was studied by thermo gravimetric analysis (TGA) and ageing effect was highlighted. In addition, calorimetric properties were shown to analyze the effect of ageing on the polymeric chains and the speculated nucleation effect that fillers could play. Moreover, Young modulus measurements were performed by using nano- indentation technique for mesoscopic scale and tensile test for macroscopic scale. Finally, the weathering effect on the morphology of exposed samples was observed by SEM to detect changes on polymer composites.