Desalination driven by solar energy represents an appealing solution for agricultural irrigation in remote areas. In this work, a desalination system based on a photovoltaic-powered nanofiltration (NF-PV) membrane is studied. The experimental work explored the effect of the influent concentration and solar radiation on permeate production, energy consumption, recovery rate and quality of the permeate product. Four cases of different inlet conditions of influent concentrations were studied. In each set, the influent concentration was kept constant, varying only the irradiance along the solar day. In addition, a unit cost of permeated water was estimated. The maximum tested energy consumption was 1.55 Kwh m(-3), with a concentration of 2,539 mg L-1 of total dissolved solids. The NF-PV system produces 2.16 to 4.8 m(3) d(-1), with a permeate water unit cost of 1.05-0.47 US$ m(-3).