JUST A WORD OF WARNING!!!!!
K4fcp has put together a magnificent tutorial which was extremely helpful to me when I was putting together my own "solar system," but BEWARE of the link to:http://www.solarsell...nt_tracking.htm
aka John Drake
These MPPT convertors are extremely delicate and easy to fry. If you disconnect your battery for any reason and forget about the very rigid reconnection rules of these convertors, you will see a smoke trail coming up from the convertor, smell a very bad odor of burning plastic, and one or more of the ic's inside will have melted down into a slag heap. The seller and the manufacturer are aware of the problem, but will not stand behind their product.
Not a knock on K4fcp, just a warning for folks who might be considering these particular solar convertors.
My experience with John Drake and the charge controller he sells has been a bit better. He spent a lot of time with me on the phone (possibly on his nickle, but I forget) answering my questions about how safely to install it.
I'm not technically savvy enough to know whether this would make a difference in case of screw-ups in the order of reconnecting the leads, but I paid a bit more and got the 10 amp controller, and I also got an inline fuse installed. Then my set-up is such that I never really have to disconnect and reconnect the charge controller: It is velcroed right to the battery and has a few inches off the female end of the extension cord from the solar panel permanently wired to the controller.
I haven't yet been able to work out installing a gromet to keep the whole assembly from getting ripped apart accidently while moving the solar panel around, but since this set-up requires leaving the battery cave door open when the panel is plugged in, I am just cramming the short female end of the cord down between the door and the body of the trailer for the time being.
No mishaps doing it this way so far. I'm not clear what I will need to do to protect the charge controller when removing my battery from the trailer for the winter and reinstalling it next spring, but expect to be able to call John Drake for clarification if I can't figure it out from the instructions.