Desalination is an extremely power hungry process. Either of substantial amount of pressure is required or evaporation of the water.
However recent process by MIT looks to hugely improve the efficiency of such a system. Using a series of evaporators and condensing sections they have been able to reach an efficiency of 385% ( Due to the reusing of this ambient heat allowing an efficiency well in excess of 100%)
Using this new process A device costing only around $100 could in theory deliver fresh drinking water for an entire family.
This process does not use photovoltaics but instead uses the heat to evaporate the water. A prototype that they put on an MIT roof, produced over 5 litre of of high-grade clean water per square metre of the system per hour.
While there are substantial areas of desert that are too far inland for desalination to help ( for instance the Sahara desert) there are substantial areas of the world where desert and sea life side by side. This new device could well be the way to make life in these areas easier, and the pressure on local rivers substantially smaller.