The photovoltaic (PV) panel is a device of photochemical energy conversion. It produces electricity from the sun light by PV phenomena. The cell temperature of the PV panel effects on its degradation rate and life time. So, it's very important to installing a cooling system combined with PV system to enhance its efficiency. Among many cooling technologies, this paper reviewed two common techniques. These techniques use water as an active cooling and phase change material (PCM) as a chemical passive cooling. This paper studied the effect of using cooled PV driven reverse osmosis (RO) desalination system. An experimental setup was installed to study the effect of water cooling on the PV output. It was found that the open circuit voltage (Voc) of PV panel enhanced from 32.1 to 35V when the panel temperature decreased by 19oC. The results showed that for PV driven RO, the PV output enhanced by cooling. So, the RO saline feed-water can be used to PV cooling in addition to preheating it to improve the desalination system productivity.