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RE: My mobile solar photovoltaics system, plus added charging system for battery packs
seeing how you are using 3 12v panels; have you thought about getting a MPPT charge controller and running them in series (36V) so that you can get charge out them even under partial shade/ earlier in the day? I have been looking into MPPT controllers as a way to get maximum efficiency out of a small (mobile) solar setup like yours.
I could, but I will have to run a converter back to 12volts for most of what gets run from it.I could easily reconfigure the battery bank though. so that's a plus.
the MPPT can be set to charge 12V. That's one of the ways it is able to gain efficiency. When the panels are at 1/2 voltage (shade, or when the sun is oblique), they will still be at 18V, so the charger is able to charge your batteries... At full power, the MPPT charger determines the maximum power it can extract from the panels and charges the batteries at that rate (for bulk charging).
running the panels in series, and higher voltage, also allows for smaller wire to be run from the panels to the charger...
The chargers are expensive, and on small setups its usually cheaper to add another panel to gain WH, but with our systems being constrained on size (they need to fit on a vehicle) adding panels is not always an option...