Do you mean Batteries? Ofcourse there are, energy can be stored in different forms,like raising water to a higher potential with a pump and when the pv system is down,you could let the water flow down and generate electricity.
you will find more information here. Electrical energy cannot be stored direclty for a long time,but there is always the possibility of converting it into a different form of energy and storing it and then converting back to electrical energy. You can wind something up and then unwind to generate back,store it chemically,store energy in a magnetic field,raise the potential of something other than water.
I would like to extend Divya.T, , energy can be stored in different forms,like raising water to a higher potential with a pump and when the PV system is down, you could let the water flow down during night or evening so that water evaparation loss also decreases. Hence, improves the energy efficiency of the system.
The lowest cost storage is delivering the excess to the grid and buy it back when needed. This required grid connection and a financial agreement with the grid manager. A very energy efficient storage system is using the electric energy to make hydrogen gas. This can be bottled and transported. The problem is to cool it down for liquifying and the manufacturing of very strong containers for storage and transport. If you need low technology, water heating (when yo need electricity for heat) and water lifting are the most appropriate. .
The que was very straight forward i.e the author want to store the energy generated from solar cell. commonly people using batteries. but the better solution is Supercapacitor..
An other way to store electricity from PV (or wind) parks is to use hidrolys and fabricate hydrogen(respectively, adding more chemical processes and waste CO2 to generate metanol, methane or other hydro-carbonates) as fuel .