Like any industrial process, a photovoltaic (PV) system can be subject to various faults and anomalies during its operation, leading to a decrease in performance or even system shutdown. This thesis focuses on advanced diagnosis, as well as the detection and localization of faults in a PV installation, with the aim of reducing maintenance costs and optimizing productivity. Photovoltaic solar energy represents a promising alternative to the gradual depletion of fossil resources, due to its many advantages: cleanliness, renewability, silent operation, and low environmental impact. The presented work involves monitoring the behavior of photovoltaic cells under various climatic conditions. The modeling is based on equivalent electrical circuits, allowing for the analysis of the I-V and P-V characteristics of the generator. The simulation, carried out using MATLAB/Simulink, highlights the effect of variations in irradiance and temperature on the energy performance of the system. In addition, a detailed study of typical faults affecting the various components (modules, cabling, junction boxes, converters, and inverters) is conducted, with each fault analyzed in terms of its potential impact on overall efficiency. Finally, monitoring and diagnostic methods are proposed, based on the real-time measurement of parameters and the calculation of derived quantities such as efficiency, energy losses, or the performance ratio. This work thus contributes to improving the reliability, efficiency, and maintenance of photovoltaic installations, from a sustainable development perspective and with the goal of optimal integration into the energy mix.