First I want to say this modification would not have been possible without the help of Handy Bob Solar (https://handybobsolar.wordpress.com/
). Several years ago he helped me diagnose an issue with my Trimetric Battery Monitor wiring. Since then I have read and re-read his RV solar blog over and over. I usually camped near Seattle in the winter, so didn't think solar would be worth the time and investment. But I followed Bob's advice, and spent time characterizing my power usage in all seasons and driving my consumption down as low as possible. Now that I am camping more east of the Cascades, I decided to embark on solar.There were several guiding principles of I followed:1. Know what your power needs are:
Bob strongly suggests buying a battery monitor/meter to track what's going in and out of your battery, like a Trimetric Battery Monitor. There's no other way to know what your actual power needs are, and without this information, you don't know what solar capacity will suffice. Bob doesn't like to waste money and I don't either. I spent several years tracking and reducing my power needs in all four seasons to learn that I consume 10AH - 20AH per day.2. Don't chase the sun
- Bob is big on just setting your panels and forgetting about them and focusing on camping. He believes if you have your system designed properly, you can simply set up horizontally and leave them. Yes, tilting does get you more, but you might not need that extra 30%. I was often fully charged by 11am on my recent trip. Will probably tilt more in the winter.3. Less gear means more time to relax:
I hate moving gear around and have limited storage. I didn't want to have to load and unload another piece of equipment - even if it's a tube of toothpaste. The only gear I want to set up is my camping chair and maybe my visor. I also didn't want to worry about theft.4. Controllers belong near the battery, not on the panels:
Bob's big on this concept and I wanted to purchase a Morningstar solar controller, because this what Bob recommends, and mount it inside my [email protected]
and not have it attached to portable panels. Having this configuration means that if I ever really had to move my panels to the ground and run a long wire, voltage drop wouldn't be an issue because the panels put out 21V. Solar controllers take the higher (in my case 21V) voltage and drop it down to what's appropriate for the battery's state of charge (14.8V to 13.6 to 13.2). If you run long wires from solar controller to the battery you're causing a voltage drop where it directly impacts your battery charging. If you run long wires between the solar panels and the controller though, the voltage drop doesn't impact charging as much because you are starting out at the panel voltage (21V) versus the post-controller voltage (14.8V). Charging batteries 100% typically requires 14.8V, so if you don't get that because of post-controller wire voltage drop, your batteries will have a shorter lifespan over time.5. Rigid panels are better than flexible panels:
I am not afraid to drill holes. When I queried the forum on flexible panel results, most were less than satisfied, and if you have to remove them for some reason (like a safety recall) it's a massive pain to unstick them. They aren't as efficient because there's no air cooling. They can't be tilted in any direction and I wanted the option to set up horizontally and leave them, or tilt in the wintertime. You'll note that I have a fan vent cover, and by using brackets, I can tilt up so high as to avoid a shadow from that cover. If I really need more tilt, I can easily remove the cover. Rigid panels gave me way more options, lower price, more efficiency, and a cooler roof (the panel also acts as a shade!).These principles led me to select:Renogy 100W Panel, Rigid ($140)Morningstar Sun Saver Controller 10A ($50)MC4 Cable to go from panels to controller ($20)Windy Nation Tiltable Brackets ($50)
Here's the final product, laying along the roof, 25 degrees, facing south while boondocking. My two configurations for summer are this, and if my rear is not south, I'll put it up horizontal. Winter camping data will follow when I have that.
Default position, laying flat on roof, allows for lots of air flow, and it 25 degrees, which just happens to be a nice angle for solar exposure at my latitude.
Horizontal position used when camper rear is not facing south. @Dalehelman
thinks I may even be able to drive with it up in this position, like a [email protected]
Wire routing is a little temporary, because I didn't want to drill hole in the top until I had gotten more real camping data. Wire goes into Air Conditioning vent grille for the time being. Will probably re-route from roof into air conditioning space once I've had the solar system for a full season.
Wiring comes into grill, and to solar controller (the black box), which is temporarily mounted just outside the air conditioning compartment. I like to watch all my meters, and seeing a green charging light and watching the amps flow in is very entertaining to me. Most folks mount their solar controller by the battery, or under a seat in a cabinet, but because I wanted to observe it, I put it here.
Wires go from solar controller down inside the bathroom wall to under the seat where the WFCO is. I tapped into battery wires there (I have a Trimetric Monitor/Meter with a shunt). I did not run new wires to the battery for the solar, and have not measured a voltage drop.
Did a bunch of drawings to figure out the optimum location given that I have a roof vent cover and didn't want it to cast a shadow on the panel, especially if front of trailer was south (as in winter). Also wanted panel high enough off ground to discourage theft.
Did some wind load calculations to see what types of forces would be on the four screws that hold it to the trailer.
With a 40 mph wind, on a panel that was mounted at 90 degrees (maximum wind), each mount would get 5 lbs since there are four of them. For reference the panel weighs 16 lbs. (Thanks to @wizard1880
for double checking my engineering calcs and coming by to inspect my work.)
Yes, Commercial French Fry Cutter Suction Cup Feet. These made the whole mod possible! They allowed me to experiment with mounting locations and then when I was ready, I removed the bolts and drilled holes through them for my own mounting screws.
Before I get yelled at for ruining the structural integrity of my trailer (yes this happened before when I drilled a single hole) I'll remind folks that this is the Yakima Rack diagram showing cross beams and that the Yakima Rack is specd at 100 lbs, while my solar panels weighs 16 lbs.
Nice big beams every 8 inches. I also asked for and received an actual to-scale drawing from the factory showing the locations of the beams. I asked them for recommended screw length, and they said 3/4" long self tapping screws, so that's what I used.
These are the brackets. I've added some lock washers and nylon washers and will probably continue to tweak to make tilting to horizontal easier and easier.
This was good information to have when deciding if and when and how much to tilt. My latitude is 48 degrees, so for summer, you can see that's around 20 degrees tilt, which is why when it's flat against the roof at 25 degrees, that's why facing south and just leaving them down works well.
I use a yoga mat and bungees to keep it clean when it's parked because I live under large trees.
14.4V with 3pm sunlight in Seattle, panels horizontal (not optimal orientation, just flat)
5.25A, 3pm sunlight in Seattle, panels horizontal (not optimal orientation, just flat)
On my recent trip, my panels would fully charge my batteries by 11am at the latest. They started charging from the second the sun came over the horizon (when I was sleeping) to when the sun set totally. That all-day charging was a wonderful thing to witness. Before I even woke up, my solar panels were doing their job to help combat the 24/7 power usage from my LP detector, fridge on propane, USB fan, etc.
Happy to provide answers to questions. I know that some of you love your solar suitcases, and that's great, it's just not the solution I wanted for my own personal needs. I live in Seattle, and there's very little sunlight here and so I am trying to camp where there's lots of sun now. There were very specific reason why a suitcase did not meet my criteria, and so I'd appreciate it if this thread didn't turn into a suitcase vs fixed panel debate. I'll also note that if for some reason I did want to remove these from the roof, buy an extension wire, and set them on the ground, I could do that, because the brackets are easy to unscrew and remove. But moving solar panels around is not how I want to spend my camping time, and so far, the places I enjoy camping more are wide out in the open, or get enough partial sun to fully charge by early morning.
I'm also happy to add any more photos or provide more details. I wanted this to be a preliminary post of why I went the route I did, and how it worked for my first outing at central WA boondocking and while at Lincoln Rock State park.