I don't think my Banff is wired that way by Hymer.
I'm not exactly sure how it is wired, but I doubt that it goes through the inverter for two reasons. First, solar panels produce DC and the batteries are charged with and produce DC so no inversion is necessary. Second, if the batteries are turned on, they charge from solar even if the inverter is off. In the FB Carado Banff group, there has been a lot of discussion about wiring and settings (neither of which Hymer did correctly). There are also wiring diagrams, and you should be able to get a better answer from some of the other folks there. The wiring and settings errors made by Hymer mostly concern lithium iron batteries (the settings were not correct to prevent overcharging and things that should have been wired to the charge sides of the batteries were wired to the discharge sides). I paid technicians to make all those changes, but I have a rough sense of what they did. If you don't have lithium iron batteries, some of this won't be relevant for you. One last point, Hymer (before they collapsed) tech. support told me that the solar panels are basically a trickle charge. That has been my experience when I camp with no external source of electricity. My refrigerator will keep running for 3 or 4 days with just solar, but, after that, I need to run the engine to bring up the voltage. I'm hoping to install propane fuel cells (once the ones I want are available) to address that.