Be sure to put the converter on the batteries and the solar controller on the batteries separately--ie in parallel. Do not put the converter upstream of the controller so its output goes to the controller's input.
Your new converter is made by PowerMax. I have PowerMax converters and solar and they can be on at the same time, no problems. When off-grid and the batts are down after a few cloudy days, I do a generator powered recharge so the converter is at its max amps. If the sun is now out, I get additional amps from solar for a faster recharge.
