Adding 880w of solar to a T@B 400: Part I

A few years ago, Giesi (my wife) finally got to fulfill one of her long-time dreams: We purchased an RV. Not just any RV, either: We got a "tear-drop" camper. It's made by a company called nüCamp, and they're considered to be very well built. The RV industry in general is known for poorly built things, so think about nüCamp as being "decently built", i.e. no major surprises, and some truly thoughtful things in the build, like hidden pipes for running wires, to make fishing them later a lot easier.

The model that we got is a 2018 T@B 400, mainly because it was the smallest one that they made that was big enough that I could stand up inside it. The general idea with a teardrop camper is to spend most time outside, and only sleep and do some cooking in the camper. Of course, when we took it for a few weeks around the south-eastern US a few years ago, we found that "outside" isn't always convenient when it's pouring rain, and "inside" can be pretty cramped when there are four people in a tin can sized for maybe two!

At any rate, live and learn. We have some clever solutions now to some of the challenges of life on the road. We learned many of those solutions from other campers who freely share information on the many online forums, blogs, and videos dedicated to this topic. (Thank you all for your help!)

This year, we are planning some trips, and we will likely need to be able to stop without a campground (they're all booked solid in many parts of the US), or in the less popular campgrounds that have no electrical hookups. That forced us to think through an upgrade to our camper, to make it more self-sufficient. Specifically, without being able to plug in for electricity, we wouldn't be able to run the air conditioner -- or much of anything! (The RVs are typically using 12v battery power unless they're plugged in.) Speaking of plugs, there were almost none in the camper, which is hard nowadays when everything is electronic. And when traveling, we often have very weak cell phone signal, which impacts my ability work. (I still have to work when we're traveling, because my boss is a complete jerk, and you can tell him that for me.)

We had some minor issues with the bed (comfortable, but just barely, and a bit too flimsy), and some water ingress around the utility storage door. We also had some missing "necessities", like a secure storage space for valuables and important papers. Both ceiling exhaust fans had already died, even though they were only 2-3 years old. And lastly, we had already some useful items for the RV, like a bike rack.

So this spring has seen a number of big RV projects, as we get ready for trips to visit family and friends. To start with, we wanted to be able to power the RV with solar, with a wish list of being able to use the air conditioner (a huge power hog), even when we aren't plugged in. This normally requires a generator, but we hate generators. First of all, they're noisy, and other campers hate the noise almost as much as we do. Second, they burn gas, and we've been trying to burn less gas. We're not tree-huggers, per se; we just want to do our little part to reduce the amount of pollution and waste that we create. It's hard to be a real tree-hugger when you're driving an RV around, which obviously means burning a fair bit of gas. (At least until we can get an electric tow vehicle, which is still a few years away, it seems.)

Back to the challenge: How to produce a lot of power for the RV? And how to have plenty of power without a generator? So I did a lot of measurements, reading, and calculations, then I watched a bunch of YouTube videos made by crazy people who live in RVs and make videos for YouTube so that they can afford to live in RVs, and I determined that there was a viable solution: Solar.

Keep in mind that the T@B is curved -- it's called a teardrop camper for a reason! And it's also small! So getting enough solar onto this camper was going to be a challenge. I started by identifying the necessary technology, called a flexible solar panel, and then figuring out how much I could stuff onto the T@B 400. It turns out that I can fit eight 110 watt solar panels onto the T@B 400. That is 880w (almost a kilowatt) of max power, but with the curve of the RV, we're guaranteed to never see that much power. (My target was a predictable 400+ watts on a sunny day, which we do actually get, and then some!)

Next, I needed a power handling system for the incoming solar power, and for charging the batteries, and for turning that power into AC (alternating current) to run the AC (air conditioner). It turns out that I needed some major battery upgrades for this, and I found a great American-made solution, Battleborn Batteries. I'll cover the details of the battery setup and the electrical setup in a subsequent blog entry, but for now, if you're curious, the package that I got is a 400 amp hour kit, with lots of other stuff included that I needed. I was able to talk with a salesperson there, Cory, who told me a bit about the company, answered most of my questions, and even helped get me a discount that made the decision a little easier. (Hint: If you are thinking of buying from Battleborn Batteries, give them a call and see what they can do to help make it a little more of an easy decision!)

What I want to cover in this article is how I put the panels onto the RV. This isn't easy work. It's a combination of mind-crushing tedium, infuriating challenges, and body-destroying contortions. On top of that, it's very expensive, and will take a huge amount of time. And if that description doesn't scare you away, then keep reading! (Please note that the Amazon links are "smile" links on purpose; this allows you to pick a charity to support, if you happen to purchase anything. If you don't know what "smile" is at Amazon, and you use Amazon, then please look it up, and pick a good charity to support.)

First things first: The panels. I purchased 8x 110w flexible solar panels. This is a tight fit for 3x panels in the front, but plenty of room for 5x panels in the back. Here's what it looks like from the back:

And from the front:

As I write this, I want to capture all of the ideas and challenges and solutions, but I'm sure to miss a few of them. So I'll start by at least trying to capture the big ideas. To begin with, solar panels need space behind them, and air flow, or they overheat and die young. I found a solution (with the help of those crazy YouTube nuts) that lifted the panels off of the roof. Second, these solar panels bend, and need to be securely mounted, but I did not want to drill through the roof. Again, I found a solution from various videos and posts: 3m VHB tape, which is used to attach car body panels and things like that. Third, I wanted to make sure to minimize the "wing effect" of driving with these things on the RV at highway speed. Again, some ideas from crazy YouTube videos came to the rescue.

To provide an air gap without screwing through the roof, I purchased 12x "T" tracks (each has 4x 48" tracks, so I ordered 3x of these). These attach to the roof with 3m VHB tape. WARNING: The tape I got is too wide, so I had to cut it to size, which is a huge amount of prep work; if you try this, please just order the right size for what you are taping on, and save yourself a lot of work!

In the above photo, you can also see the white, outdoor-friendly, cove molding (inverse quarter round) that I found at Lowes (via their website) used to divert air over the panels when driving. I mounted this material both in front of and behind the panels, to further minimize the potential "wing effect". So here's the result of all the prep work, before I even attempted to install anything:

The install is fairly simple in concept, but very tedious and error prone in practice. This is a huge amount of work and really hard to do with just one person. Also, that tape never wants to come off if you do it right (and you must do it right!), so the more hands you have the better to get it right the first time  -- because doing it a second time is basically not an option!

Before I mounted the panels, I carefully added some weather stripping:

This is a bit of an experiment, so I don't know yet how well it will work. I wanted air flow to cover the back of the panels, yet at the same time, I wanted to minimize the wing effect when driving. Also, I wanted something on the back of the panel that would help make sure that the spacing of the panel away from the RV would be maintained over time. My solution is a made-in-America weather stripping product that I cut to size. There are three tracks to mount each panel on (lower, middle and upper tracks), so the area between the lower and middle track is the "lower" section of the panel, and the area between the middle and upper track is the "upper" section of the panel. I placed the weather stripping on the back of each panel before installing the panels, so that the panel would have gaps for air to flow in at the bottom and flow out at the top of both the "lower" and "upper" section of each panel:

To mount the panels on the tracks, I used bolts that slide into the track, then the solar panel goes onto those bolts, then slide on a washer, a lock washer, and screw on a lock nut to hold them on. All stainless steel, of course.

As you install, you need to make sure that the panels will fit, that there will be room for the cove molding, that things are all level, all spaced evenly, and so on. I'd suggest taping down just one track first (either top- or bottom-most), and then attach the panels to that track, and put the other two tracks onto those solar panels, but keep the tape backing on (i.e. not sticky)! That way, you can measure and estimate and adjust before taking the tape backing off the other two tracks, and when you do take it off, just do one at a time! Take your time, and do it right! Tighten the nuts, but not too much; the lock washers and nuts should hold well, but you'll want to check them every month or so to be safe.

Just for installing the solar panels, the planning time was about 20 hours, including reading up on how to do it all. Then another 20 hours of prep work to get everything  cut and de-burred and cleaned and pre-taped and ready. Then about 20 hours of install time (with most of that having two people working). This is a serious commitment of time and effort, so please do not underestimate just how hard it is. If you mess up, it will be infuriating and hard to fix, so slow way down, measure everything several times, take good notes, and mock things up (without attaching things permanently) any time that you aren't sure about something!

Once the panels were installed, I wired them. I already had a solar shut-off switch installed inside the tab:

It hides in the closet:

This is very important: ALWAYS MAKE SURE YOU HAVE A HIGH POWER CUT OFF SWITCH! It allows you to work on the system without dying painfully. You're in a tin can with a lot of power doing stuff, and the tin can is itself a ground point (but insulated from the real ground by rubber tires), so if things go wrong, you will get shocked, and it could be horrible. Please be careful. Your batteries should have a shut-off switch (the T@B 400 comes with a good one), you can unplug the shore power, and you should be able to safely shut off the solar power as in the pictures above.

Wiring the panels together requires a solar connector crimping tool and the connectors. For wire, I used 10 gauge silicone-coated (high temp) wire with UV protection, all copper. I ran in series, so I didn't need quite this big of wire, but DC loads on wire are not to be trifled with; trying to push more amps through a cable than it is meant to support is a fire hazard, and a fire inside an aluminum "tin can" is a certifiably Very Bad Thing. Also, never, ever use "copper clad aluminum" wire, or any aluminum wire; only use 100% copper wire ("tinned" or "pre-tinned" is also good, as long as the wire is all copper).

This brings up an interesting question: Is it better to run the solar panels in series or in parallel? I chose to run in series, because the voltage goes up but the amperage stays the same, and as long as the Victron solar charger can handle the voltage, and as long as you are using proper safety procedures, all is good. Of course, wouldn't you know it, the solar panels that I purchased were sold with a VMPP voltage rating instead of a VOC voltage rating, so my calculations were all wrong, and the Victron charger couldn't handle the total voltage (probably as high as 180+ volts). As a result, I unplugged the front three panels, and I am currently adding a separate, smaller Victron MPPT charger for those panels. The remaining five back panels come in well under the voltage cap of the Victron MPPT charger that came in my Battleborn kit.

I routed the wires through the side (not the top!) of the camper, using some highly rated hull pass-throughs from a brand that I know well. That said, I'm not convinced that these pass-throughs are worth using; they're a bit more complicated to install, without any obvious benefits for my RV use case. Nonetheless, they do appear to work well enough. I angled the wire entry towards the back of the RV, and down towards the ground, so that the cords come in at a 45 degree angle from behind and below, in order to reduce the likelihood of water coming in when driving in the rain. Here they are, with temporary (not all bolted and secured) wiring:

The inside wires are well hidden unless you hold the camera up to the ceiling, like I did for this "checking the work out" shot:

I have an irrational fear of poking holes in the top of the T@B, so all holes that I put into the T@B are on the sides, where I am more confident in my ability to place and seal them (usually with butyl tape, but these through-hulls had their own rubber gaskets included).

Lastly, I do try to buy locally, and I do try to buy American. This is very hard to do with specialized needs, like an RV project. Most of the local hardware places carry very limited combinations of sizes and materials, e.g. they do not have the parts I need in stainless steel. I was glad to find Battleborn Batteries were made in the USA, but the Victron products almost certainly are not; you can't win them all. Amazon is convenient, but I still try my local hardware store (i.e. not Lowes or Home Depot) first for a lot of things, and I do feel a bit guilty having to buy so many parts online. There's nothing wrong with buying from Amazon, or from China, but when you can, try purchasing locally so that those stores can still be there at some point in the future when you may want to be able to just go down the street and grab what you need.