Light powered umbrella uses a special type of fabric that can generate electricity from rain drops. The electricity is then used to power LED's that will light your way.
Light drops looks like any ordinary umbrella, but illuminate in the dark.
If still wondering about its working here is answer for your queries
As raindrops fall on the umbrella, the potential energy caught on the umbrella’s membrane is used to generate electricity.This powers LED's embedded in the umbrella, setting off a blaze of light.Heavier rain makes it light up ever brighter. Designed by Sang-Kyan Park, the Light drops umbrella is yet to be released.
I really hope this product actually works, or will work in the future :)