Give your smartphone solar assist with this modification from instructables
Phones tend to be out of battery right when you need them most. With this project, you can extend your phone’s battery life just enough to make those emergency calls! You just have to set your phone out in the sun for a while, and you’ll have just enough power to send a text or make a short call.
To modify your phone, you’ll need the following:
An approx. 2″x2″ solar panel I got mine out of a broken electronics kit
A dremel w/ cutting disc I got mine at Harbor Freight Tools
A Smartphone The project can also be done with a typical phone.
Electrical tape In my case, all I had was bright red, shiny tape. This made for an interesting project.