Adding an Inverter to a camper Solar Setup

What is off-grid camping without tv?! Not really camping I guess. Glamping? Don’t judge.

The only easy ways I know to get the 110v outlets in a camper working with no shore power is with either a generator or with an inverter hooked to a battery. Solar is our preferred method of off-grid power, so today I’ll be sharing our version of the latter option.

As it turns out, this was an extremely cheap project for us. Mainly because we already had a basic automotive 500W inverter in our old XJ that never really experienced much use. I did have to order the proper circuit breaker and purchase some 8 awg wire and terminals. The breaker size depends on the wire size and the wire size depends on how many amps you’re drawing and the distance between the battery and the inverter. There are equations that help you determine this, but a quick google will come up with plenty of charts to make the job easier. Do not oversize your breaker - if your wires get too hot and the breaker doesn’t trip, you may end up barbecuing the whole rig. For our setup, I used this 50 amp breaker from Amazon. Being water proof is a nice perk, since it’s mounted inside an exterior cabinet. I plan on locking the cabinet up tight to make sure the seals are set, but I am still brainstorming ideas for a removable shield to protect the inverter as well.

I ran to Autozone and purchased two 6 ft lengths of 8 gauge battery wire, which comes with four terminals to a pack. You’ll need a crimping tool to crimp your terminals after you’ve cut your wire to length, so grab that if you need it. They did not have a black 8 gauge, so I used black electrical tape to denote the polarity.

First things first: Toss a blanket or towel completely over your solar panel and check your monitor to make sure there is no power being generated before you unplug your panel connectors. My MC-4 connectors had a well-placed warning on them. Once your solar panels are flat lined, unplug your connectors. It is at this point that you can freely loosen your battery terminal screws and remove the cables for the charge controller. If you installed a quick disconnect switch from your panels to charge controller and/or charge controller to battery, you have the luxury of just flipping a lever.

Now that everything is disconnected, it’s time to move on to mounting your hardware. The closer your inverter is to your battery, the less voltage loss you’ll experience. If you have to run a longer length of cable, you should make sure that your wire gauge is sized up appropriately. I mounted mine to the front of the storage cabinet as close to the battery as possible, which required just 3 ft. cable lengths. Once your inverter is mounted, find a nearby spot for your circuit breaker. Your inverter’s positive cable will be connected to the switch, and then a positive cable runs out of the switch and down to the battery. Think about accessibility. If the breaker trips, you don’t want to be climbing halfway into a storage compartment to reset it. The negative cable runs directly from the inverter to the negative terminal on the battery. I drilled a hole in the floor of the bin and ran the wires down and right up to the battery.

Now, you may be wondering how I am going to get power from the inverter to the electrical outlets in the camper. The answer is: very carefully. I have a 110 adapter for my shore power cable, which I plug into a drop cord rated for outdoor use. Inverter to drop cord > drop cord to shore power > shore power to campers 30 amp inlet. There is one big step that you must take before you do any of this, and that is flipping the breaker for your converter/charger. When you are plugged into shore power, your converter converts the AC current to DC and charges your battery. When you are plugged into your inverter, the power supply is from the battery itself. Your battery will be effectively charging itself, which results in attrition and a dead battery over time.

I take it a step further and flip every breaker except the main breaker and the breaker that my 110 outlets are on.

My next report will be on overall battery drain as we use this system on our next camping trip. Will we need to connect both panels? Will the toll of charging phones and watching TV in the evenings overdischarge the battery? We shall see!