Adding Solar Capabilities to Our Travel Trailer
Our Passport camper was advertised, stickered, and sold as “solar-ready”. We didn’t know anything about campers, and we didn’t know what we were getting into with our adventures. We just thought this was a nice feature to be able to put solar panels on our rig someday. Once we started camping, and especially planning our first big adventure, it became pretty clear that we wanted solar. Having more power lets us go off grid longer. Plus, we get many more options for camping sites on our adventures. We aren’t fighting for spots with hook-ups…or even “spots” at all! With our solar and battery upgrades, we can pretty much camp anywhere, anytime, for days on end. And we don’t have to give up our creature comforts such as lights, running water, and even movies on a rainy day
A Brief Lesson
Most travel trailers and campers have two electrical systems built into them. A 12V DC system and a 110V AC system. In a lot of campers, the 12-volt system runs the basic items to tow and camp with the trailer. The basics…not the frills for glamping. It runs the essentials: trailer lights, brakes, tongue jack, interior lighting, water pump, furnace blower, and so on. With this power, you can use the camper to have some of the more basic creature comforts almost anywhere.
However, the truly power-hungry stuff, like the A/C and the household outlets around the camper that run your coffee maker, your hair dryer, or your television, only work if you plug into shore power, the electrical hookups at modern campsites. But even without those power-hungry luxuries, the battery on our camper, “Bessie,” allows us to “camp” with running water, heat, and lights in our home away from home…. Still pretty fancy and comfortable compared to a tent for 6 in a blowing rainstorm. And it allows us to access more places to get away from crowds, closer to nature, and gives more options for camping than if we only chose sites with modern hook-ups. As long as the battery holds out, that is.
Dealer Supplied Battery
When you pick up most campers from the dealer supplies the battery and propane tanks on the unit for sale. Campers typically ship without those items to the dealer. So usually, but not always, the battery on your new camper is a run-of-the-mill deep cycle lead acid battery. You can imagine that the dealers typically don’t spend top dollar to put the highest quality, biggest capacity batteries on new travel trailers.
But you need a battery to use it and tow it safely. So they have to put one on there before you buy it. This is the battery that provides the 12-volt, direct current or DC power that a camper uses for its essentials when you aren’t plugged in to external power. These “deep cycle” batteries are similar to a car battery, but one designed to be run down and charged up more frequently, instead of putting out a lot of power (amps) all at once when you crank your car each morning.
Lead Acid Battery Limitations
These batteries are usually about 80 amp-hours each, and most modest trailers have 1 battery so there’s about 80 amp-hours of power available if you run it all the way down to zero charge. An amp-hour is pretty much exactly what it sounds like. Take however many amps the things you are using draw from the battery and multiply it by how long you want to use it and, voila! You have how many amp-hours you’ll need to run your stuff.
The problem is that lead acid batteries lose their lifetime quickly if you draw them below about 50% charge. A 50% drain is considered “deep-cycle” for these types of batteries. So really we have about 40 amp-hours to work with to get us through a camping trip off-the-grid. For us, with minimal use of lights, water, and heat we can last about 36 hours. Our trailer draws a little under an amp when nothing is running due to the little power parasites like the radio, the clock display, propane and CO detectors – stuff that’s on all the time, drawing a little power.
So a weekend camping trip from Friday evening to Sunday morning checkout is possible. But there’s no extra. And with 4 kids turning lights on, flushing the toilet, and charging their phones, it was just something that bugged us and prevented relaxing in our adventure base-camp. So how do we make the battery last longer without using a noisy, gas-powered generator? There are two main options: get more or bigger batteries or add solar! Doing both is even better; you can add solar to the existing battery. More on upgrading the battery later!
“Solar Ready”
Our camper boasts being as “solar-ready.” It came with stickers on it saying so, a weird plug on the front of the camper, and no documentation! Awesome! We think the idea was that you look at the stickers with a solar panel brand logo on them and buy the panels from whichever company signed a deal with the RV manufacturer (Zamp Solar in our case). Then you have the dealer hook everything up for you.
All of this sounds easy, but we live about a 2-hour tow from the closest dealer, each way. Moreover, it’s the COVID pandemic…so they are booking out until next winter, and the parts are backordered anyways. So, what to do? Figure it out ourselves. Nothing pays back better than learning how your camper works. Even if you don’t DIY stuff, knowing how things work helps you use your camper more fully. Also, you be more informed when something goes wrong (not if, when).
DIY without a Manual
For us, with our Keystone passport, we found out that the manual is very general…probably for many different models. And it didn’t have any information on the solar. But hey, there’s a plug on the front of the camper that said “solar ready” and some outlets inside the camper that had stickers that said something like “solar ready, inverter prep”. And there’s a weird bump on the roof that looks like it has some plugs in it. So obviously they did something to prep the thing for adding solar panels and such.
Taking a closer look at the plugs on the top and the front of the camper, there are indeed connections used to connect solar panels to batteries. With some “Googling,” it turns out the plug on the front of the camper, near the battery where the frame starts under the trailer, is an “SAE” connection and the roof bulb had “MC4” connectors. There was also a weird box inside the pass-through area, right above the front solar plug and behind the battery area that covered up something. We were pretty sure that the plugs were connected in some fashion to the battery with smaller extra wires that came out of the front of the camper and connected to the battery with the main power cables to the camper.
Solar Panel Options
So, how to add solar panels that plug into the camper and, presumably, charge the battery? There appeared to be two choices: roof panels and external/portable panels on the ground or an external mount. We decided pretty early on that we were going to go with portable panels, at least to start with. Why? For a couple reasons, really. For one, if the panels are on our roof and we park in a nice shady spot then we aren’t getting much solar, right? If we have portable panels, we can put them a short distance away from the camper. Park in the shade, charge in the sun. The other reason is that we were really, really, really hesitant to drill holes in the roof to mount solar panels. So we looked for some portable panels.
Solar panels basically connect to your battery to charge it up when the sun is out. Some of them even come with simple alligator clips to clamp on the battery terminals like mini jumper cables. Between the panels and the battery is a “solar charge controller.” This regulates the current flow and voltage of the panels to the battery so that they can charge the battery efficiently without damaging it or overcharging it. Usually, you can’t just connect solar panels to a battery directly. They run at different voltages, and the batteries can only charge so fast or so much.
The Right Solar Panels for Us
There are a lot of good choices for portable panels out there, and it was very confusing, especially for us just learning about campers, batteries, panels, etc. Which brands do we get? How many watts do we need? Why are some flexible and some rigid? Well, the sticker on our camper said “Zamp Solar”. Turns out that is a brand of solar panels, apparently with a deal with Keystone to promote their brand. Zamp panels looked like great panels and it looked like they had the right connector to plug right in.
Unfortunately, they were pretty expensive for our budget with 140 watt systems coming in right around $800! So we looked for other options. We decided to look for about 200 watts of power. At 12V, 200 watts would be about 16 amps maximum current output possible, current equals the power divided by the voltage. Nothing is perfect, and there are always losses in the controller, cables, etc. Not to mention, that would require the most perfect, hottest sun ever, so we didn’t expect to get a full 16 amps. But even half of that would charge the battery on a sunny day.
Renogy for the Win
There were many options that came up on Amazon and other retailers with names we hadn’t heard of in our research before. But one brand that came up repeatedly and that seemed to have decent reviews was Renogy. Renogy was offering a 200-watt “suitcase”, which means it folds up, with a waterproof solar charge controller included and a case for about $300.
The Renogy 200W portable solar kit includes a charge controller already attached, MC4 connectors, an MC4 to SAE connector (that fits our camper’s plug) and a canvas case to hold the folded up panels. There’s a suitcase-like handle to carry them, but they are a little awkward. They are really heavy (about 40 lbs) and larger than you would think, even folded up. But, with a little muscle, or some help, they are relatively easy to set up. We bought a 20ft extension cord, MC4 to MC4, to help us to have a little more reach to move the panels into the sun at our campsites.
The only little issue we had was that plugging in the solar panels to the plug on the front of the camper caused the charge controller to display a “polarity reversed” error message. After some digging in the forums online, it turns out that Zamp wires their plugs in the reverse polarity of most other plugs and brands. So we needed a polarity reversing adapter for our Renogy panels. Cost us like $9 for a 3-pack and it worked perfectly once we installed that. We set the charge controller for our “deep cycle” battery type (as it can charge several types of batteries) and put the panels out in the sun!
Here Comes the Sun
Turns out, in full sun we can make 10 to 12 amps! Which means we are putting those amp-hours back into the battery for every hour we have full sun on the panels! For a battery that has about 40 usable amp-hours that’s a serious power boost! Of course, we don’t get 11 amps all the time. Sometimes it’s cloudy, or we can’t angle the panels perfectly towards the sun at all times of the day, but even in less than ideal conditions we can get a couple amp-hours for 4-6 hours/day. That gives us enough extra power to not worry about using the camper like it was meant to be used on a weekend trip or even a 3 day weekend.
We use the radio, lights, and water when we need it. For us, it was a good investment for removing worries while camping. We can choose any site, not just the sites with electricity, and still have our creature comforts. And it opens up a lot of possibilities for longer duration stays or longer distance trips where we may not have power for several stops in a row as we venture further out. There are a lot of good-looking brands out there. However, we’ve been very pleased with the performance and capabilities of our Renogy solar kit.
Be sure to check out the other Camping Gear We Don’t Go Without!
Heads up: Any items discussed above are items we use and love. If you click and purchase from one of our affiliate links, you may add some change in our “Next Big Adventure” jar. And we promise to share that adventure! This comes at no cost to you.
