Portable Solar Charger

I wanted to make a portable solar charger that could be used to hold various accessories and keep my phone in the shade while charging. The first thing I did is buy an inexpensive panel that could output around 300ma @ 20 volts. After finding one I bought a USB car charger that can take an input voltage of 12-24 volts and connected the panel's output to the chargers input. After verifying that it does charge my phone, I made a small wooden box and used hinges to hold the panel. I used half an eraser as a wedge to make the panel hold an angle when its in the open position. This setup will fully charge most cell phones in about 4 hours.