Power Supply/Solar Panels

After doing research on the power requirements, I found that the Raspberry Pi uses about 12v. I also did some research on how to make a battery charger that uses solar panels. For that it looks like we will need a blocking diode to keep the power gathered by the solar panels from escaping back out. I also found a solar panel which can be wired for 12v or 6v use, and will fit on the outer casing of the Police Alert. Since I am not sure about everything that has to go into this I have emailed Que lab in Albuquerque for Advice. I am currently waiting on a reply from them.