3 input automatic power supply

[donkey]

Hey I am after a design for my solar setup. I want to have the battery powered by either solar or wind when its available and if not then mains power. of course I want to go with a overcharge protection and minimum voltage protection.
I was thinking the easiest way was a microcontroller but thought I would ask before going head deep into it to see if anyone has any other ideas of how to approach this on the cheap

 

[GreenGiant]

my first thoughts are diodes, it could charge from either source without the risk of barckcharging the other, overvoltage Im not sure, but undervoltage just throw a zener in there or a few in line to get the voltage drop of the lowest you safely can