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.

Step 1: Materials

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.

Step 2: Cutting

Open up your smartphone, until you reach the back. My smartphone was a ZTE Majesty, so all I had to do was pop off the back with my fingernail. Unfortunately, not all phones are this easy to open, but you should be able to find instructions here. Regardless of the type of phone, you need to reach the very back panel of your phone. Using a Sharpie, trace the perimeter of your solar panel onto the inside of the very back panel of your phone. Using your dremel, cut out the outline.

Note: It is better to make the hole too small, than too large. You can make a hole larger, but you cannot make it smaller.

Sand the edges of your hole until your solar panel fits into place perfectly. Be careful not to scratch the back of your phone with the sandpaper.

Using electrical tape, tape the solar panel into the hole from the inside, positioning it so that the actual "solar collector" faces the outside of your phone, as shown.

Step 3: Wiring

Run the wires to your battery terminals, making sure to connect the red wire to the positive contact, and the black wire to the negative contact. You can solder the wires if you want, but all I did was place them against the contacts and press the battery into place, thus securing them in the proper position. Clip the back of your phone back into place. This may take a little persuasion considering that it is now slightly more bulky than it was at the beginning of the project. Enjoy your Solar-Assisted Phone!

Update: Thank you to user "depmode" for giving me inspiration to draw the circuit schematic. As best as I understand it, the diode will help prevent electrical backflow.

Update No. 2: User "chubby8" said, "I think it would be safer to find a solar panel with 5v -12v output, and use a 5v regulator and a diode, and then solder it to the inside of the USB charging socket. +5v to the +5v pin, ground to the groundpin (or any ground on the board). Your phone will then regulate the charging of the battery.You could maybe use the solar panel you have along with a joule thief to step up the voltage, followed by a 5v voltage regulator but I'm really not sure.Best case scenario is it won't charge the phone very much, even on a sunny day.Your current setup won't charge the battery, only risk damaging it and possibly your phone as well. But well done for having a go, hope this helps!"

Considering chubby8 probably knows more than I do about electronics, please follow the above instructions. Thanks!

I am a beginning electronics hobbyist, and want to improve my instructable projects. Please comment, suggest improvements, or point out something I unwittingly missed! Thanks!