To meet the increasing demand for clean water as the scarcity of natural and clean water is a vital problem that facing many rich or rural regions of the world no difference between developing countries or Europe or the rich Arab Gulf countries where the clean water is rare and consumed many times higher than the available water. What most people do not know is the enormous cost of desalination and consumption of large amounts of petroleum fuels (such as oil and natural gas), the cost of which represents a large share of the total cost of desalination Therefore, when used to produce desalinated water (solar desalination), solar energy provides a renewable, clean, safe and free energy source that reduces dependence on oil fuels, reduces greenhouse gas emissions, and provides a sustainable source of desalinated water production. This paper presents the Reverse Osmosis process, its key elements, and the results that could be generated by its combination with solar photovoltaic technology.