Startup Idea : Pin-Point Homeless people

Like I and many others, we have a passion to help homeless people. At one point when I was little, I remember my father offering a homeless man food instead of money because inadequate spending may be one of the causes as to why they are homeless. I came up with an idea that involves a simple, cheap GPS device that can somehow be powered by solar energy or batteries. The homeless person can wear this special device around their neck and/or wrist. They hold the ability to turn it on or off for privacy concerns. Building an app that correlates to the device would in turn create location-based device that anyone can simply go onto their phone and find a homeless person whom they can help in any form they choose such as giving them food, clothing, or even a simple task or job. Funding I think should be public through donations. Need some experienced app builders as well some knowledge in low cost GPS devices.