This paper describes the potential of the development of a seawater desalination system that combines the technologies of reverse osmosis (RO) and photovoltaic (PV) to deliver 100m3/day of sweet water. Silicon cells are chosen for the PV array and the polyamide thin-film composite seawater Filmtec membranes are selected for the RO system. The software ROSA is adopted to study the influences of the feed pressure on the performance of the system. It is found that as the feed pressure increases, the specific energy of the plant decreases but the percentage of recovery increases.