This is my take on a already well documented little project. Very simple to make and a good introduction to electronics and solar powered stuff. Works just fine too. You need to generate 5-6V to charge a phone.
You will need:
Solar panels. I used 2 panels. (3V I think )
5V voltage regulator
USB female jack/connector
Epoxy or hot glue
Step 1: Bits & Pieces
Gather together all your stuff. You need to make sure you know which side is top and which side is the bottom of the USB plug and the voltage regulator so that you solder the correct pins.
The regulator keeps the power output to 5v.
Step 2: A Series of Solar Panels
A USB port from a computer puts out 5.5V for charging of phones and mp3 players. So you need to get about 5-6V from your solar panels. In this case I need to solder the solar panels in series in order to double the voltage output. (3V each panel). Solder the positive of 1 panel to the negative of the other. (Its just like putting 2 batteries in a flashlight)
Step 3: Solder It All Together
Hook it all up!
The positive wire from the solar panels goes to the LEFT pin of the regulator. (mine is upside down in the photo)
The negative wire from the panels goes to the MIDDLE pin of the regulator and is also connected to the RIGHT pin of the USB plug. (Again, mine is upside down in the photos)
Then connect the last pin of the regulator to the other outside pin of the USB connector.
The 2 middle pins are not needed.
If you follow my pictures it will be OK....
Step 4: Glue
I used hot glue to hold it all together but an epoxy or duct tape will work fine.
Next time I would make it so that the 2 panels hinged in some way so that it could fold together.
Step 5: It Works!
Here it is charging my HTC.
I have it under an incandescent bulb as it was dark outside when I finished....but it works!