We all know radiations are electromagnetic in nature. So the basic idea is to filter the electricity from the electromagnetic wave and store it in the form of electricity for future purposes.
# the idea : if we concentrate the radiation on a conductor and place that conductor inside the permanent magnetic field and in some intervals if we vary the concentration of radiation the magnetic flux will vary and due to variation in magnetic flux current will be produced in the conductor we can now store this current in the battery. We can utilize any radiation e.g. sunlight, gamma radiation, radio waves, etc.
#uses :the only limitation to uses of this type of device is the imagination, But just to name a few uses: in automobiles, space shuttles,daily life equipment, home appliances.