Installing Off-Grid Solar & Electrical in our Renovated Airstream: Part 2

For us, one of the perks of renovating our vintage Airstream was that we got to design not only the interior and layout, but also the entire power system from the ground up. The first part of this series provides a high level overview on all that, so you may want to go read it first.

Back? Ok, good.

In this article we’ll look at the actual installation - from wires to connectors to switches to relays and fuses and everything in between. Hint - there are sooo many things in-between!

We’ve been using this setup for over 4 years living mostly off the grid (boondocking), but also in campgrounds, friends’ driveways, and even at farms and wineries. We get around. 

And now we’ve setup shop permanently on our off-grid desert homestead using the same system day in and day out.

Keep in mind we’re a family of 6 living, working, and homeschooling with this power setup full time. And I can count on one hand the number of times we’ve had to pull out the generator to top the batteries off - all of which involved lots of trees blocking our panels.

This setup has been solid as a rock, and one of the main reasons we’ve waited so long to write this is that we really wanted to make sure that we could wholeheartedly recommend the setup after real world usage. 

Shout Out to Samlex America

As you'll see below, writing, photographing, and illustrating all this information was a herculean task. We'd like to thank Samlex America for sponsoring this post, and giving us the time to really dig deep and get into the nitty gritty details.

We've been using various versions of their PST Inverters from the start, and they've been fantastic. They also have a new Evolution (EVO) series that combines your inverter, charger, transfer switcher and more into a single unit. Let's just say I could have massively simplified my setup with one of these. Or as I'll probably repeat multiple times throughout this article - "Should have gotten an EVO!"

Anyway, thanks Samlex!

Airstream Renovation Electrical Wiring Diagram

Ever wondered what all the major connections look like on a 12V system like ours? As part of this deep dive, we created a very detailed replica of our wiring setup.

I know I'm a visual person, and sometimes I just need to see it all laid out no matter how many words there are to explain it.

This is as big as I can make it here on the site - if you'd like to download a vector PDF that you can zoom in on, grab a copy here:

Article Overview

1. Planning Your Power
2. Gauging & Running Your 12V Wiring
3. Creating a Wiring Guide
4. 12v Fuses and Grouping
5. Running 120V Wiring
6. All other wiring (radio, tanks, displays, thermostats, cable, internet, remotes
7. Organizing Connections with DIN Rail Terminal Blocks
8. Mounting Solar Panels
9. Wiring Solar Panels & Charge Controller
10. Locating & Connecting Lithium Batteries
11. Converter
12. Inverter
13. Transfer Switch
14. Wiring Tips
15. What Would We Have Done Differently?
16. Shopping List

Having a digital version of this wire list guide is such a huge time saver. For starters, you can make changes and not have to re-write the whole thing. You can pull it up on your phone, tablet, or computer without digging through your cabinets for the original. You can search the text, sort the columns, and find what you need instantly. We think it's pretty handy.

Run each wire you need for every appliance, switch, light, display, and more. Keep reading, we're going to cover additional wiring you might need besides power below.

To wire this up, you’d run a positive line off your battery through a 50A breaker switch and onto a fuse block. Then you’d connect the load lines from each group to a spot on the block and fuse them appropriately.

Audio Deck

Before Spotify and Apple Music there was thing thing called the radio. You may even still use it in your car! Our 1972 Airstream Sovereign Land Yacht came with an 8 track and AM radio installed. So we decided to keep the speakers in their original spot (upgraded, of course) - and install a digital audio deck. This lets us jam out to the radio or connect any of our phones or tablets to stream whatever we like.

Audio Deck Cables include: 

• Positive Wire
• Negative Wire
• Speaker Wires
• Antenna Cable

TV Antenna

Speaking of antennas - we don’t have a television, but made a conscious decision to install a TV antenna for a few reasons.

The first is that we use the raise, lower, and turn functions in conjunction with our directional cellular internet antenna so we can point directly at a cell tower and get the fastest speeds.

The second is that TV antennas also boost radio frequency bands. So our audio deck antenna cable is actually plugged right into our TV antenna with this special adapter.

Turn the antenna booster on, and you’ll see a huge difference in the radio signals you can pick up.

Just in case, we also ran an extension antenna cable over to my office area should we ever install a TV there and want to get HD signal over the air. Just a bit of future proofing.

TV Antenna Cables Include:

• Positive Wire
• Negative Wire
• Motorola to F Connector
• Antenna Cable

Tank Sensors

Want to know how full your fresh, gray and black water tanks are? Tank sensors are a great way to get a quick check. Are they super accurate? Not necessarily. Once you’ve been in your trailer long enough you’ll become intimately connected to how much water you’re using and where it’s going. So while we learned to rely on these less and less - it’s a good idea to run those wires to a monitor panel.

Tank Sensor Wires Include:

• Tank Sensor Wire Harnesses Connected to Probes Installed in Tank
• Ground Wire.

Switches

Want to remotely control things like lights, appliances, and more without pulling fuses? Switches are your friends! But they can bring additional complexity so use wisely.

Obviously, light switches would be the most obvious example. You probably want several groupings of lights you can control. So as you’re planning your wiring, make sure you have the necessary cables run from the lights down to the switch, and back to the power center.

Other ways we use switches: To turn our entire internet setup off and on to save power at night and preserve the batteries in our cellular hotspots (they don’t like being plugged in all the time). Also we use a switch to turn our hot water heat off and on. It didn’t come with a built-in switch, and sometimes it needs to be reset.

Switch Wires Include: - each switch will have it’s own requirements, but generally you’re just breaking the positive power line to the appliance so you’ll have one wire coming from the appliance and one back to the power center.

Thermostat

If you want to control the temperature in your RV by way of air conditioner or furnace, you’ll need a thermostat. Usually you can use a single thermostat, but that means it’ll have several wires connected to it from multiple sources.

Thermostat Wires Include: Thermostats are all very different, so make sure to read your manual to see what wires you’ll need to plan for.

Mobile Internet

Need a reliable, robust internet setup? We’ve got you covered - you can read all about it here or grab a copy of the guide here. Since we’re talking about running wires let’s take a look at what cables you’ll want to plan for if you’re installing an internet setup.

• Directional Antenna - this is attached to our TV antenna and uses a CA240 antenna cable run through our refrigerator vent to our cell signal booster.
• Omnidirectional Antenna - this is mounted to our roof and uses a CA240 antenna cable run through our refrigerator vent to our cell signal booster.
• Omnidirectional Wifi Antenna - this is mounted to our roof and uses a reverse polarity CA240 cable run through our refrigerator vent to our our router to provide Wifi outside the Airstream.
• In addition, you’ll need 12v positive and negative power to the cell signal booster and router - plus a way to run the internal cell booster antenna close to your phone or hotspots.

BMS Display

Your BMS or Battery Management System will likely have a way to connect a display so you can see your battery capacity and usage. Ours uses a simple video cable and momentary switch wires to page results on the screen. The display is also hooked up to 12V positive and negative power.

Of course, your setup could be totally different. Be sure to check your manual for wires you'll need to run.

Solar Charge Controller Display

We have a separate IPN ProRemote display for our Blue Sky Solar Charge Controllers. This not only lets us see exactly how much power our solar panels are putting out, but gave us crucial programming abilities to set up the chargers to work properly with our lithium batteries. You’ll need to refer to the specific spec of your batteries to know the best way to program. AM Solar has a great document that should get you started.

Charge Controller Display Cables Include:

• Data Cable (telephone cable) through the roof
• Shielded cable to connect to shunt. Check with your specific manual instructions to see what wires you need to run.

Inverter Display

Getting to and turning off our inverter became a pain in the butt so we added this remote switch display. It also uses a simple data cable and was super easy to install. The hardest part was finding a place for it where we could run the wire since we were finished with the renovation and living in it when we added it.

The simplest way to explain how these work is this. Let’s say you have wires #1 & #2. They are the positive and negative wires for your furnace. The furnace wires have to run through the ceiling down to your power center and get fused and connected to the battery for power.

Instead of running one end of the wire directly into your fuse block and the other to the load line of the furnace, use terminal blocks instead. Strip the end of the wire and run it into one side of the block. Screw it down to make contact. Then run a new line out the other side to your appliance or load that’s been screwed down as well. When both are inserted and screwed, it completes the connection.

You’re probably saying at this point - "well, what’s the point? Seems like you’re just adding a few extra steps and additional expense into the mix." But here’s where it gets fun.

There’s a disconnect version of the terminals with a flip up section that breaks the connection on the wires. Need to troubleshoot an appliance and don’t want to take your whole system out? Look up what number wire it is and cut its power. Of course you could also do this by pulling its blade fuse - but if you have more than one thing grouped on that circuit it could be hard to troubleshoot.

There’s also the terminal block jumper. This is a copper bar with insulated screws that connect to the middle of the terminal block so you can join multiple lines together. Not only does this give you a nice visual of how you may have grouped lines, but by jumpering two blocks together all of a sudden you have four inputs instead of two. This is a great way to take a single wire and power multiple smaller loads without tape and wire nuts.

Finally, there’s a wonderful labeling system. Small blank plastic tabs snap in, and even allow for two on top of each other in case what’s coming in one side is different than the other. For example, we used the terminal blocks to group our fuse load lines. So the individual wires come in the bottom, and we jumper them together at the terminal before running a single line out to the fuse block. That means the bottom label is the wire # and the top label is the fuse #.

The beauty of this system is that its so clean and easy to maintain - if you need to use it for some of your “other” type wires, it works great for those, too. Having the actual connections contained inside the plastic housing keeps things safe, but also stacked super tight to save space.

We even put in small DIN-Rail terminal blocks at each major area where wires came out of the ceiling or under cabinets. Making changes or fixing problems is so much easier when you can unscrew, add more blocks, and rearrange on the fly.

We’re huge fans.

We also wanted to be able to tilt the panels to a 45 degree angle to help on those winter days when the sun traveled at a lower angle and spent less time in the sky. As much as we loved the Renogy solar panels, their bracket mounting system left a lot to be desired, especially for a rounded roof!

Turning to AM Solar, we found a much better (though seriously expensive) mounting bracket and foot. But the extra tall ones gave us room to mount on the curve and still keep the panel high enough to run the wires underneath. They also sold tilting bars, but were so outrageously expensive that we just bought their knobs and went to the hardware store and cut our own bars of aluminum and tapped them ourselves.

It’s not convenient or easy to tilt the panels, but with a collapsible ladder I can get them put up in maybe 10-15 minutes total. One of the big goals of the renovation was to stay away from unnecessarily complicated products so we weren’t interested in any sort of “automatic” tilting motor.

That’s just one more thing to maintain and eventually break. Our cheap aluminum bars work just fine and keep us more in tune and aware of how we’re using the Airstream. i.e. It’s much less likely that we’d drive off with the panels up since I have to climb up and put them down myself.

Once all the hardware was attached, we primed the aluminum surface with 3M tape primer and used VHB tape to stick the mounts directly to the aluminum skin of the Airstream. VHB stands for “very high bond,” and so far it has lived up to its name. Everything is still nice and sturdy, no screws required!

The Airstream has a lovely refrigerator vent that we were able to run the cables down through without cutting holes in the roof. We made sure they routed down the side a bit and then back up to the vent so that water couldn’t run down the cables inside. Then we added a plastic bracket to make sure the wires wouldn’t rub through their insulation on the aluminum corner and a custom wood bracket to keep the wires nice and tidy as they run down the wall.

We may be a little OCD.

Anyhow, the 10 wires (5 positive, 5 negative) converge in that distribution block inside, and then run to a heavy duty switch in case we want to cut all solar energy coming into the batteries. Then the wires run into our Blue Sky Solar Charge Controller.

From there, the positive wire runs through a 100A circuit breaker and to the solenoid attached to our BMS. The negative wire runs to our negative battery post.

A couple of years later we added two 200 watt Renogy Solar Suitcases. They’re basically the same panels on the roof, but joined to gather with hinges, legs and latches. This gets us 400 more watts (for a total of 900 watts), and allows us better sunlight gathering, especially in the winter months. These ground deploys fold up and store in handy cases when not in use.

To easily connect and disconnect these panels, we used a weatherproof 12V Plug & Receptacle and installed it in the Airstream during the renovation. In order to use the single plug for both panels, we connected them in series, and made sure to match up the positive and negative wires on both pieces. There’s a 3rd connection, but we don’t need it for this application.

Unfortunately our original solar charge controller could only handle 40A max, so we had to get a second unit and run the wires the same way. Since we can unplug the panels from the outside we did’t add a disconnect switch.

The cool thing about the Blue Sky charge controllers is that you can daisy chain them together. The first one that is connected to the IPN ProRemote (with additional programming) is the primary controller, and the secondary controller inherits the same settings. Because they are MPPT controllers, the ground deploys send through higher voltage in series, but it is converted to a higher amperage for charging.

The remote display shows the combined total of both charge controllers as if they were a single unit. High five!

The first step was to install the sense boards on each battery and connect them together. In our case, each battery pack totaled 3.4V so wiring them in series produces a 13.6V system. The sense boards send important info back to the BMS like temperature and voltage for each cell.

The BMS (Battery Management System or EMS - Energy Management System) provides several important protections for your batteries.

1. Checks each battery cell for under voltage or over voltage situations - if one is triggered it cuts power
2. Checks each battery cell for temperature extremes - if too cold to charge, for example it won’t allow it
3. Equalizes battery cells - if it sees a cell with higher voltage it will temporarily shut it off and allow the others to catch up - this elongates the life of the batteries by keeping them in sync.

In our particular setup, the BMS uses separate OV and UV relays and a solenoid to stop power going into the battery during those situations. I can see the benefit of being able to easily replace a relay or solenoid, but as you can see from the wiring diagram the Elite BMS is mind-bendingly complicated to set up.

I’m not going to go into great detail for wiring this particular BMS because it’s old, overly complicated, and based on a few conversations with Larry from Starlight Solar - probably not connected the *best* way 😂. It works for us, though. And if you go down this path you’ll be studying your own EMS wiring guide anyway.

We’ll cover more of the “what we would do differently” down below, but just know there are other options out there like BattleBorn that have much of protections built right into the battery and aren’t as complicated to install.

The next step is to build your own "trunk" wires to connect the batteries together. We used copper bars bent at a 90 degree angle and bolts to connect the positives and negatives together.

Time for an honest review. After 4 years of using these things full-time, they are rock solid. The only issue we’ve had was the failure of two sense boards, and I’m pretty sure we caused it trying to run a 1HP shallow well pump off our inverter. Because we bought directly from Elite, they did some troubleshooting over the phone, and all we needed to do was buy new sense boards. I should also give a shoutout to Larry from Starlight Solar Power Systems who helped me diagnose a few things as well.

For us they’ve been (mostly) pretty great. However, I’ve spoken to a few folks who are using a newer version of their BMS and had some stability issues. And as I'm writing this, we've just had one of our new sense boards fail again after 6 months of use. Not to mention the first replacement they sent me was also faulty. So there may be some quality control issues there.

Should have gotten an EVO

So here’s the thing. Samlex (the makers of our inverter) graciously agreed to sponsor this deep dive post. And during our talks with them they mentioned a new product called the EVO (or Evolution) that combines most of the large disparate appliances into one single product:

• Two separate AC inputs for shore power & generator
• Adaptive battery converter/charger
• Synchronized transfer switch at zero crossing
• High surge inverter with active power boost
• Input for solar charge controller

I know they’re the sponsor, but look at that! How much could my setup have been simplified with one of their EVO units?

FYI, these units have a max of around 50A for solar input, so you may not be able to use them to their full functionality if you have a large solar array like we do.

Finishing Up

Whew! If you made it through this article you get a high five and a cookie. We hope that with the detailed explanations and photos, the PDF wiring diagram, and spreadsheet wire guide we've equipped you to start putting your own off-grid electrical system together in your RV. 

Here's a few more behind-the scenes photos for you!

Have questions? Ask away in the comments.

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About the Author

Jonathan Longnecker is the strongly opinionated tattooed and bearded half of Tiny Shiny Home. He loves making music, figuring out nerdy solutions, exploring the outdoors, and living off-grid.

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