In PV system the alternative in night or sun set is battery then I asked about other alternative of using battery like special salts?

For PV system battery is the best. For other system like wind there is no such need of batteries as alternatives.

I don't think it's feasible because the energy that's stored in PCM is thermal energy, while the energy produced by PVs is electrical energy and the conversion would result energy losses.

Also in case you want to use the stored energy in it's electrical form, the conversion from thermal to electrical is not common at small temperature variations.

However PCM can be used in Solar Water Heaters to store excess heat during the day (Thermal Battery) in order to get hot water in the night without the need of a boiler.

Hybrid systems maybe it's more likely to use than batteries , due to high periodic maintenance for batteries , comparing it with diesel generators 

alternatives are hybrid system which uses wind and diesel power generation

Supercapacitor is other best option for storage in stead of battery

you can using salt as csp systems 

but i prefer using batteries 

i prefer use battery or from the grid

You have to think about hybrid PV-Diesel-Battery system.