singin' in the rain

i just thought of this invention, and i can't believe it doesn't yet exist!!! why hasn't anyone created umbrellas that have solar panels on them? in many places around the world, people use umbrellas as a portable shade. take japan, for instance. wouldn't it be COOL to shade yourself and at the same time, charge your phone or ipod? solar power is cheap and clean, and the technology to convert it is getting smaller and smaller. seems like the right time to grab the sun energy and make it useful and portable for our daily lives!