Pumping water for irrigation systems using renewable energy is one of the broad and viable uses. The use of renewable energy for pumping water is a perfect solution in places far from the electrical grids because the cost of connecting an electric pump to the utility network becomes expensive and sometimes difficult. Photovoltaic systems are the most common and abundant type of renewable energy used to overcome this challenge. Therefore, this paper presents a methodology for improvement the size of the PV system and calculating all the elements of this system from the PV water pumping system, water quantity needed for irrigation, the sort of plant, the microclimate, the soil, and the irrigation method to obtain the optimum electric power needed to pump the water. In the proposed work, the Farafra Oasis was chosen as a case study, an Egyptian oasis located in the Western Desert within the borders of the New …