The major problem with photovoltaic systems is to extract the maximum power with better performance and good efficiency as long as there are large variations in atmospheric conditions. To do this, we made a comparative analysis between two controllers, Proportional-Integrator (PI) and backstepping based on a photovoltaic system made up of two parts, the first is the Photovoltaic (PV) panels which are used to convert solar irradiation to an electric current, the second is a boost converter which is used to provide the maximum power. The Perturb and Observe algorithm is used to generate the reference voltage in order to follow it by the two controllers (PI and backstepping) and therefore generate the maximum power. We are considered some parameters for this comparison such asthe efficiency of the controllersto follow the reference power despite the rapid change in atmospheric conditions as well as the response time of the system and the ripples in the transient phase.