This circuit will allow you to dump excess power to an alternate load when your batteries reach max charge. Replace the light bulb with a spdt relay that is rated for the full output of your array.
Most commercial charge controllers dissipate the excess current through heat. This circuit will allow you to divert it to an other load , water heater, fans, second bank........
The voltage source is replaced with your battery bank.
Btw, thanks to Voltransistor for posting the low-high circuit. It was used to provide the signal for the comparator.
