Abstarct: Among desalination systems, the use of reverse osmosis (RO) has become very widespread due to its advantages. One of the challenges in desalination systems especially in the reverse osmosis (RO) method is the existence of a control algorithm to overcome the uncertainties and disturbances. Another challenge of such systems is their power supply. A high-pressure pump supplies the pressure behind the membrane in the RO system. The use of renewable energy not only does not have any environmental effects but also provides sustainable energy for such systems. In this paper, to answer these two challenges, at first, the integrated model of the reverse osmosis desalination system with the solar photovoltaic system has been examined; then for each part, a control algorithm is designed and simulated. An optimized fuzzy controller has been designed to track the maximum power point at different temperatures and radiation conditions in the photovoltaic solar system. The fuzzy controller has been optimized with the invasive weed optimization algorithm (IWO). The electric motor has been controlled using a fuzzy PID algorithm. The super-twisting sliding mode control has been used for the RO system. The simulation results show that the proposed algorithm for the combined reverse osmosis-photovoltaic (RO-PV) system has a good performance in different operating conditions and can remove and eliminate disturbances on the system.