I have an home built camper that I bought about a year ago. It was basically a shell. Over the past year I have done a lot of interior work, I am now getting the electrical finished. I have a WFCO converter power distribution center. I have 3 120V outlets, 0ne by it's self for an AC unit and 2 tied together GFCI by counter top and one outside. On the 12V side, I have lights, fantastic fan, water pump and water heater controls on fuses. There are 2 group 27 LA rv batteries. I have also installed 2 100w solar panels and controller. I have on order a 2000w inverter. The camper has no 12V power to/from the truck. Only running lights + and ground -. Here are some of my questions.

The solar controller says to not hook up the panels until after I connect the battery. Can cause damage. So what happens if I have to disconnect the batteries for some reason? Should I disconnect the panels first? I have a shut off switch that I was thinking of installing between the panels and controller.

What happens if I plug into shore power and the converter starts charging the batteries? Nothing? Will the solar controller care?

My biggest question is the ground screw on the inverter. I do not plan on connecting the 120V from it to the circuits already in the camper but adding a stand alone outlet just for the inverter power. I have watched several videos and they say to run a wire from the inverter ground screw to the chassis. Well the camper is all wood so there is none and I don't think the truck is right either. There will be times the camper is off the truck. Another video says to use the ground in the WFCO converter where the 120V lines attach from the RV plug. That's fine but what happens when plugged into shore power? That connects me to the main grid which is different power source than the inverter.

Lastly some folks say to ground the solar panels frames. If so, where should that wire go? The negative side of the 12v system or the ground of the 120v ac system? This seems to be for residential use not on a camper roof.

 

Im guessing that shore power and solar power grounds, should be bonded together. Bring all the grounds together.

Nothing will happen to disconnected solar panels. Technically we could say: They will be a little bit hotter. Some panels might degrade and wear out quicker. But thats splitting hairs. For all we know, panels degrade whether connected or not. Large resi or industrial panels may need covered up in hot climates. I doubt a lil rv panel will matter.

Always land the solar controller to the battery 1st. Then the panel. (Shouldnt matter anymore, but just do it the right way, it still sadly matters) Solar controller and shore power can both feed the battery, just fine. Usually.

These janky chinese controllers are the weak link. Just follow their instructions. Most will work together fine, but sometimes their FET rates will cause harmonics, and some brand combos wont work together. All you can do is try. This is still fairly new ground.

Ever notice that some tool chargers wont work when other chargers are plugged onto the same invertor? Or that 2 small invertors sometimes freak out when connected to the same battery? The battery should smooth things over, like a giant capacitor, but stuff happens with some of the cheap noisey junk out there.

 

A good controller like one from Victron will be OK. I try to always disconnect the solar, then disconnect the battery. Restart is the reverse order.

There were some solar charge controllers tested a few years ago that would let the magic smoke out if the solar was connected first. I think this was limited to the MPPT controllers. I saw PWM controllers at the RV dealer lot all the time that were connected to the solar and there was no battery at all.

It doesn't apply to you but the biggest concern with always connecting the battery first was to let the solar charge controller know what the system voltage was. Taking a solar charge controller from a 24 volt system and installing it into a 12 volt system (and connecting it in the wrong order) could put 24 volts into a 12 volt battery.

No big deal. Happens in my trailer every time I fire up the generator to do it's monthly maintenance run. PWM solar charge controllers can be a bit timid when it comes to seeing a charge on the circuit and they'll back off. My MPPT solar charge controller will still keep cranking. There is a concern that you don't want the combined set of charge devices to exceed the maximum charge amps that your battery bank can handle.

At the very least, I think the "equipment ground" from the inverter should be connected to a battery negative connection somewhere within the system. For new trailer campers, there is usually an equipment ground connection to the frame of the trailer. That's for both AC and DC.

When connected to shore power, your AC ground is at the pedestal.

Nobody does this in an RV. I have yet to see an OEM setup that runs a separate ground for the solar panels.

It might be too late but you may be able to save yourself some space and wiring by getting an inverter/charger instead a separate inverter and charger. The inverter/charger reduces the complexity of the system. The complexity argument may not apply to you since this is a custom build instead of something that comes from the factory.

You may want to add a shunt to your system so you can get a good idea of the state of charge. Battery voltage is a fairly good indicator of state of charge with lead acid batteries, but not for LiFePO₄ (should you ever upgrade).