Then option 3 sounds like the most cost effective solution,but maybe with the COMET 12/24-Volt 40 Amp Solar Charge Controller instead of the Renogy. Three of those panels in parallel gives me 240 watts. Even when I have to replace the batteries, I will never have more than 225AH.
Or, if I stay with option 4 with a Grape Zenith 40 amp MPPT controller, instead of having 3 pairs of solar panels wired in series, I go with 2 sets of 3 solar panels wired in series, or even wire all 6 panels in series? That controller spec sheet says the panel array can go up to 100v. That will cut down on the amps going through the wires.
