Despite the enormous solar potential of African countries, the main concern of autonomous PV systems is still in its poor efficiency. This paper proposes an approach to improve the performance of these autonomous photovoltaic systems subject to “disturbances and observation”. An autonomous PV system model adapted by the MPPT control (Maximum Power Point Tracking) is designed and studied. The system PV generator is the MSX60 module which produces a peak power of 60W, an optimal current of 3.5A and an optimum voltage of 17.1V under standard test conditions (STC). The mathematical equations developed for PV generator performance modeling are based on the current - voltage characteristic of the modules. The complete simulation of this model under Matlab / Simulink software has enabled to find the maximum performance point of the photovoltaic systems according to the different inducers of loss of availability. The simulation results have been validated by experimental data from the National Agency of Biofuels of Mali.