Ok, thank you.
I'm still trying to wrap my head around the concept but I think I get why they wire panels this way.
They wire (some) panels that way due to how the panels are made. If they put the contacts on the backside of the solar cells, they get a bit more power because the cells are not partially blocked by current carrying metal strips on the front of the cells.
But, for some reason, putting the contacts on the back creates a situation where if they wire the panel negative-ground and the aluminum frame is grounded to the planet (which it will be if installed on a building) a small surface charge builds up between the cells and the aluminum frame, which causes the cells to become slightly polarized. This reduces the number of photons entering the cell to produce electricity and reduces electrical efficiency slightly.
Apparently by wiring the panel in a positive-ground configuration, it causes that surface charge to dissipate, alleviating the problem.
If wired straight from the panel, controller to the battery it's a single path of electrical flow between the negative and positive. With the solar is part of that circle it adds power to the circuit to which the battery absorbs the power as needed.
It's a single circle with a PWM controller, which is just a high speed switch.
But with an MPPT controller, there are two circles, one on the solar side and one on the battery side.
Now, connecting the negative to chassis ground as I did changes that path and begins to try and charge the entire truck? This is what confuses the controller as the chassis becomes charged to Output Voltage from the solar panels it sees the batteries as fully charged.
Is this remotely close to what's happening? If not I'll delete the post as not to confuse anyone else!
That's the right idea. As I said - you create a bypass around the controller to the battery.
Adding panels is not the same as adding a new light or device to the truck, it"s an in-line charger…
The alternator is also an inline charger that does the same job. But you didn't wire the alternator in a way that bypassed the voltage regulator...like you did with the solar.
