This paper presents the first reverse osmosis  brackish water desalination system operated  by solar electric power (PV) in West Bank- Palestine. The system is built in Zbaidat village –Jordan valley to demonstrate the utilization of solar energy in water desalination and to provide the inhabitants with the desalinated drink water. Design and evaluation of the system are presented. The annual average of daily solar energy in Palestine  amounting to 5.4kWh/m2.day  was  considered in the design. The total PV peak power supplying the RO-desalination system is 5.182kW .The system delivers an  average of 11.9m3/day , which corresponds to a PV peak power of 435W necessary to deliver 1m3/day  of drink water from brackish with a  salinity of  2681mg/L. The energy needed  for desalination of the specified brackish water is  2.35kWh/m3.