First and foremost, I must dedicate this post to Matt and Diana over at Adventurous Way, specifically their in depth research on RV solar and inverter power. While we never plan to full time in this rig, we do want to have a capable off grid electrical system. This might seem counterintuitive given the scale of our generator, but getting out on the road beach camping helped steer us in this direction.
That said, the heavy research side of this project was done in my mind, but the installation would still require a thoughtful layout for everything to fit. Eric is no stranger to the Renogy 100 watt solar panels in this build, as we have them on our shed and chicken coop.
We ultimately installed a Victron 12v/3000va/120amp inverter/charger, Victron SmartSolar MPPT 100/50, Victron Smart Shunt, and Victron Cerbo GX. All of the devices are hardwired to the Cerbo for communication in their respective formats, and the Cerbo itself is wired via Cat6 cable to our Pepwave Max BR1 MK2 for internet connectivity. On the outside we installed six 100 watt Renogy solar panels, and rewired most of the 12 volt side of the trailer. We have two relatively new lead acid deep cycle batteries, and plan to work these into the ground before we upgrade to LiFe components.
*Solar and battery update* Our current setup is now ten 100 watt Renogy panels, one 400ah LiFePo battery for the house, and one 11ah battery for the generator. Updated installation at bottom of post.
*Update #2 July 2023* We replaced our defective 400ah battery with a Victron 12.8V-330ah unit, with VE.Bus v2 BMS, and added a Victron 30 amp DC/DC charger.
The first step was sourcing all of the components and wiring, which is fairly extensive. Check out Matt’s posts in his solar series for a more detailed list than I assembled. You will want to do this once, and buying high quality components up front will ensure as much of a hassle free setup as possible. Here are four of the solar panels with mounts ready to load on the roof.
Initial mock up with 10ga solar wiring. We are running all of ours in parallel for simplicity. These panels fit flush on the edges, while allowing room to service the vent should that need arise.
Our trailer is an older unit, and has zero provisions for any of these relatively newer systems built in. This is our solar combiner box, which will route three sets of 10ga wiring from the solar panels, and use one run of 6ga wire to the solar charger and battery bus. It will also allow our Pepwave external antenna to be routed through the roof as well.
Our Multiplus arrived very quickly, and was needed to really mock up the install site in the trailer.
Phillip is taking some time to enjoy blasting off in his rocket! This was a sturdy box that gave another round of service on the farmstead.
Working late isn’t ideal, but a necessity sometimes. Measurements taken from our under bed storage bay, and mocked up prior to assembly. Wouldn’t you know this was exactly one 2″x2″x8′ board? The plan here was to mount the inverter on the left, and have room for the bus bars and power wiring on the right. The notch is for a heater vent.
After a few minor adjustments, the frame is thoroughly screwed into the frame of the trailer.
It is morning, and everything is lining up! The inverter is mounted in place, and while it might not be the perfect location, it is the one that will have to work for us.
Tools and parts, and parts and tools. There was a ton of tedious work on this project, despite the relative compactness of the setup.
One of the last pieces of scrap wood from our shed build wound up being near perfect for our electrical panel. Positive and negative bus bars are mounted, along with inverter shut off and smart shunt. 2/0 gauge welding cable was used throughout the battery side, to allow for a full 200 amps of current for the inverter. We have a 30 amp RV, and the 2400 watt output of the system is adequate for our needs.
The panel is mounted, and a through hole to the generator bay was drilled to allow access to the 120v circuit input and output.
Here we have the power leads coming into the inverter, along with the input and output for 120v.
Over in the bay next door, 10/3 SOOW wire was used. We had a length from a previous project, and needed just four feet extra to complete this stage of the install. This will feed generator power to a 30 amp plug, and feed 120v back through to the house circuit. Don’t fret, we didn’t let any wire touch bare metal, see below. The 20 amp outlet is on a separate circuit from the generator, we didn’t want that circuit to be completely inaccessible.
Here the system shaping up: 2/0 power and grounds on the 12v side, and 30 amp 120v wiring on the house side. The junction box houses the outlet powered by the generator, and the 30 amp plug can be utilized there or shore power, as being demonstrated in this pic.
Split loom was used to insulate the sheet metal in the generator bay.
The 12v side of things is coming together, as both the generator and house needed to be rewired through the bus bars for power monitoring. This is the configuration we will run most of the time on the road.
The 4ga wire on the left is replacing poorly spec-ed house wire on the right. This is the generator starting circuit, and will simplify the 12v wiring under the trailer.
New holes were drilled in the front header of the trailer, which is relatively thin metal. This will allow the 2/0ga wiring a new and protected transit to the tongue of the trailer, to the batteries.
In the upside down world….
Up front, a piece of 20ga galvanized sheet metal was cut and bent to allow the mounting of a master on/off switch, along with a catastrophic fuse in case of a major short.
It isn’t my ideal layout, but this will work. All of these components are IP66 rated, which is pressurized water spray certified, and more that enough to be outside the rig.
All 12v battery wires are crimped and finished with appropriate color heat shrink. I prefer all black cable, as it blends in and can be used on both polarities. The chassis grounds were also sanded and wired with 4ga wire.
Moving up top, it was decided that the wiring from the roof to the storage bay would transit our interior closet. It was time to drill! In all, 69 roof penetrations were made. (Plus 32 for the additional panels.)
Non-leveling sealant was used everywhere, as you do on the roof of an RV. This was given plenty of time to cure before the wiring began.
Here the solar panels are mounted, and all three power conduits wrapped in split loom. Self adhesive tabs and zip ties were used to secure the loom to the roof, as well as the connecting y’s for the panels. We opted to use the quick connect terminal ends, as opposed to permanently connecting the wire ends.
Wiring installed, and strain reliefs are tightened with some sealant as insurance. This is all of the solar and cell wiring for the roof.
Wiring on the roof is complete! You will also notice our new refrigerator vent cover, which disintegrated when we washed the trailer the first time. Eric tried to remove the full length sticker from the cover, but it was fighting a battle no one else was going to win.
But we aren’t finished on the roof just yet. The air conditioner was exceeding the safety shutoff threshold on the inverter during rotor lock start up. A soft start module was installed, and dropped starting amperage by over 60%. We can now run everything on battery through the inverter!
We bought a Bluetooth enabled soft start module, and it is easy to interpret the data via the app.
The missing link between generation and storage: the closet. We opted to install our cell/network appliance where it is accessible, in case SIM cards need to be changed. We also mounted the solar charger and inlet fuse here as well. Starting the wiring for everything!
There was a lot going on in this small space, look at how many zip ties were needed!
Everything is finalized and cleaned up. Our Pepwave has two cell, two wifi, and one GPS antenna. The Cat 6 wire is running to the Cerbo GX in the storage bay below. We are using a fuse as our protection and shut off here, there aren’t many scenarios that will need to be disconnected.
Two switches were installed in the closet face, the top for our Pepwave, and the bottom for the inverter. The inverter switch is lit white when the power is on, and not lit when the power is off.
The wiring from the closet to the generator bay was a little tricky, as it had to align top to bottom. This meant that the holes needed were not able to be made close to the edge, and had to be drilled outboard as much as seen here. All wiring entering the bay has rubber grommets for protection.
While all of the components work without a communication hub, the Cerbo allows access from anywhere in the world, which is pretty cool if you ask us 🙂 It also allows communication with the Multiplus, which unlocks all if it’s programmable features. Keep in mind you will need a Windows computer for Victron’s editing software…
We are not using the touch screen at this time, but we are leveraging the Victron VRM system. Here is a screen cap cooking dinner, running an Anova water immersion heater, Instant Pot, as well as charging the battery bank on generator power.
This is a screen cap of the web interface, where all of the settings and optional data can be displayed. Firmware updates are over the air, which is a plus.
All in all, we can run our Nespresso coffee maker on battery in the morning, before generator hours are allowed. This is an expensive build without the lithium iron batteries, but the quality of life aspect is well worth it.
Full disclosure regarding the solar install: panels mounted in a “near level” orientation like this do not generate nearly as much electricity as you might think. This was a sunny afternoon on December 5, 2021, and all six panels have unobstructed sunlight.
*Solar and battery update below*
After a few trips with the above setup, it became apparent that the angle of the panels reduced their effective production well below expected output. The highest generation seen was 450 watts, from 600 watts worth of panels with sunlight directly overhead. Some calculations were made, and specifications of our charge controller consulted.
The Victron SmartSolar MPPT 100/50 has a maximum charge rate of 700 watts in a 12v configuration. Upgrading to the next model would cost double this unit, as well as needing to upgrade our wiring scheme from 6ga to 4ga; and adding a sister would require additional wiring, which we wanted to avoid. A decision was made to add four more panels, assuming our 75% output rate: we would expect 750 watts from our ten 100 watt panels. The end goal was to not only increase our peak output, but to also increase the duration of production during the day with a larger array. The compromise is that any extra wattage over 700 will not be captured by the system, and this is something we can live with for now.
The first step was installing another watertight relief on our combiner box. Luckily there were a few options to choose from, and it was as simple as drilling a new one inch hole, and installing the fitting.
We wanted to continue the same installation pattern, but the next vent was not centered properly. This would mean panels on the passenger side would be protruding, and that wasn’t something we wanted to have visually. Changing the alignment allows us plenty of room for servicing the rooftop, should the need arise.
All of the panels were measured, spaced, and squared up. Two more 10ga runs were needed, and they were installed in split loom to match the original install. You can see the duct tape on top of our AC unit, the cover cracked when we installed the soft start kit 🙁
The combiner box is getting crowded, but not full. I would highly recommend this AM Solar box to anyone wanting flexibility for their system.
All of the wiring has been cleaned up, and panel mounts sealed. We are happy with how this addition turned out!
How does it work? At high Noon, we are generating 700 watts of input! The above capture is with the inverter on, and fridge running electric only from room temp. This should pair nicely with our inbound 400ah LiFePo battery.
Note the time of 7am, and it is a typical overcast morning in San Diego. Our trailer also has two pine trees shading the panels until about 11am, and we are already charging our battery bank.
The final phase was swapping our two group 24 lead acid batteries for a single 8D 400ah lithium iron phosphate battery. This will double quadruple our storage capacity, and should alleviate the low battery voltage situations we have run into so far in the mornings over coffee.
The new battery is here! Never mind that we were out of town, and had to make an exception on delivery. Fee paid to brown, and our 85 lb good is in hand!
LiFePo are not orientation dependent, and this lot of scrap shelves will come in handy more than once in this retrofit. This one will be the base of the battery on end for support, and will aid in the tying down the battery.
It turns out we have the perfect nesting place for the battery right next to our inverter. In the end, we don’t’ lose any storage at all.
The base is screwed to the floor, and the mounting straps are set up for X and Y axis.
The battery passed the test fit, and is getting closer to the permanent installation. We wanted to mount it a hair further away from the inverter, but there was not enough clearance under the bed supports.
Our fuse and switch from the tongue were relocated to the storage bay, and mounted on yet another shelf remnant. This was attached above the bay, upside down. The electrons won’t know the difference.
The tongue mounted batteries had the temperature sensor installed, and it needed to be relocated again. The inverter cover was removed for the simple transplant.
Boom! All battery connections are terminated, and all settings have been updated. It was a process for sure. An ANL fuse block was installed for the positive wire running to the tongue, in the event of a short circuit. The power is needed for our electric jack, and we have a place to connect our air compressor as well.
Speaking of settings, it is a shame Victron only supports a Windows .exe program for edits of the inverter firmware. Well, we know how to deal with this.
Our trailer tongue with its now naked configuration. We dropped 91+ pounds on the front, and only added 80lbs further back. A win no matter how you cut it!
All in all, no storage space was lost, and a ton was gained.
One additional issue that was not foreseen involves our generator. The 8D battery is clearly listed as “not for starting”, and they are correct. Even the very low current needs of our Honda starter trip the BMS in the battery, and it shuts down. Back to the online store for more materials…
A small lead acid battery was bought, the same size as our Honda EU6500. This is mounted inside the generator bay, and it will be isolated by a Victron Argo Diode 80 amp device. While there is room to work, it is tight nonetheless.
That is a wrap! The generator starts right up, and I think we can put a fork in this project. Time will tell how *this* setup works in the field. Stay tuned 🙂