I found this today while digging up info on charge controllers. Some guy designed it. The kit is ~$15 shipped to you. You have to solder it together. It appears it only handles about 6A, so its only applicable for a very small system. But, some of us here have small systems. In a small system you don't want to pay much for a charge controller. So, here is a great solution!
ghurd - Hurd Solar Renewable Energy | Dump Controllers