In a recent video series I did about how I installed my RV solar set up, I mentioned the final hookup schematic which you can find here as a PDF or below as an image. See further below for the videos on how to install, connect and hookup your RV DIY solar set up.
Hi Pippi,
I discovered your YouTube Channel. A while back. When I was searching for How To Build a Solar Panel. I really like your Videos. And have been watching, them ever since. It’s been great to see your Projects. And your hard work and dedication. In both finishing your projects and documenting them on video. To share with us. Thank you, for sharing. Anyway… I was thinking. About, how you could trace down, those “Mystery” Wires. I’ve done allot of Projects of different types, over the years. Mostly, by my self. With no one help. And tracing down wiring and Testing (Ringing them Out). Can be hard to do. Without someone to help, on the other end. There are some Ring Out and other Electrical Testing Tools, you can buy for this. But, Multi-Meter Leads. Are too short to do a Continuity Test on long cable runs, such as yours. So, here are some other ideas. You could hook up a 12VDC Light Bulb or a 12VDC Powered Device. Such as a Music Player. And use this as a Tester. You could also buy a Buzzer or Beeper. To make a Testing Device. Or, a Mini Cassette Player or Radio. That runs on less than 12VDC. Could be used. By attaching it to a DC to DC Step Down Converter. Like, the one’s that Plug into a Cigarette Lighter Plug, in a Car. But, which ever device and method you choose. Connect your “Tester” somewhere on the Circuit, that you want to test. Say, the back of of your Disconnect Panel, inside of your Coach. Leave the light on or leave the Music Playing. Then go out to the Battery Connections, under the Hood. And Disconnect the “Mystery” Cables. One at a time. If you can see the light, go off, from there. No need to run in circles. If not, then run inside and see, if the light goes off. Or if the Music, is loud enough. Then you can hear, when it stops. I’ve used Lights, Fans, Hair Dryers and Car Stereos, etc, in this way. It works great and you don’t have to spend an bunch of money on Test Equipment. Also, there is one caution. I would like to share with you. About working with DC Current. I does seem safer, to work with than AC Current. Since, it does not Shock you, like AC does. Well, unless you grab hold of a Distributor Wire. While the Engine is running. Or if someone is Cranking the Engine, that is… Even if you get a Direct Short. You usually only get a few Sparks. But, if you get a steadily connected Short, in a DC Circuit. The wires will heat up and melt their insulation and can burn anything in contact with them. Very quickly. And I believe. This can happen, much faster, than with AC Current. I’ve seen this happen, to many over the years. I’ve worked on Cars and done Building Maintenance, since 1975. So, I’ve made a few mistakes. And I’ve seen some simple mistakes start fires. Don’t clean Oil Spills, under Natural Gas Water Boilers with Gasoline! Not, that I’ve ever done that;) One thing, that worries me, in your wiring. Is, something that seems fine. Until you think of a Direct Short Situation. You, have some of your Grounds. Screwed directly through the Carpet, in your Coach. And I’m afraid that if there were a Short. Anywhere in that Circuit. That Carpet could heat up and catch on fire. And you would not know it, until, it was too late. If I remember right. You did one, inside in a Cabinet or in a Closet. And I do remember the one you did recently, in your new Battery Bay. I know… Everyone hates, those Self Appointed Internet Safety Monitors. But, I hope you can see. The validity, of what I am saying. I know your Dad, is an Electrical or Electronics Engineer. And I know, you can talk to him, about this stuff. So, perhaps, he can help you judge my advice… Here’s an example, of what can happen. I have a 1983 Van. That my uncle gave me. A few years, before he gave it to me. He had mentioned to me. That he had trouble with one of his fuses constantly blowing. So, I told him about an old trick. That I had learned, from some older guys. Wrap a piece of Tin Foil or a silver Gum Wrapper around the blown fuse. And it will work, again. But, just use it for a short time. Say, just to get you home. Well, evidently… He did this and just left it in there. So, he burned up almost ever wire in that Van. Now, he was not a novice. When it comes to Electricity. He was an Air Conditioning Repair Man. And he did Building Maintenance on Hospitals, for many years. He did AC Electricity and Air Conditioning Work, for a ling time. And he knew what he was doing. But, I guess. He didn’t know as much about DC Electricity, as I thought. When he later, gave me the Van. He had rewired most of the Circuits. After burning up the wiring. He used many different colors of wires. And they are almost impossible to physically run down to trace out. There are still a few little problems, with it. Like, if you turn on the Heater Fan. It burns up the new ignition Fuse, under the Hood. And the Engine Dies and wont Restart. Until, you find and replace that fuse, one little fuse. Hidden, in a wad of Wiring and Fuses. Connected Directly to the Battery. Anyway… Also, I’ve seen how Auto wiring. Can degrade and connections corrode. Quicker, than you man think. Causing Resistance and Heat Build up, in the Wiring. I use a Corrosion Preventative Gel. On all of my DC Connections, that are anywhere near or on a Battery. And on the Grounds, that are exposed to the Elements, Rain etc. I can’t remember the names or brands. But, they are easy to find in a Auto Supply Stores and Online. And connections can loosen up, too. Due to vibration. When going down the road. So, make sure all of your connections are tight. I try to always use lock washers. Wherever I can. Or else double up on the nuts. So, as to lock them together. I think you do great work. And you can plan and remember your plan. To share it with others. Better than I can. So, keep up the good work and enjoy your Trip!:)
Don
Excellent work on the solar set up. You put a lot of thought and work into getting your rig working on the sun light. In your last couple of videos I saw a couple of things. Straight out of the batteries you’ll want a disconnect so you can remove power if necessary for maintenance or emergency. I would also add a disconnect to the line that runs up to the former battery location.
You do have fusing for most things but not straight off the battery. You’ll also want to fuse items coming off the insulated post at the former battery location. I didn’t see what you fused the line running to there, but the maximum 3/0 will carry is 200/225 which is way more than those other lines would. Likely they would become fuse-able elements causing a fire.
Finally, I suggest covering all exposed connections with some liquid electrical tape. The stuff paints on and dries pretty quickly and creates a water tight and electrically isolated covering preventing shorts.
Keep up the good work!
Great suggestions, thank you!
I love you, Pippi! ???
Hi Pippi, if you see this, hope you do, what size panels did you end up going with? Just curious, they look like maybe 140Ws?? I have 150W x 3 on my little toy hauler and just installed 100W x 3 in the flexible light-weight panels on my new addition, a 2017 Northstar Laredo SC truck camper… carried by a 2017 Ford F-250… readying it a trip west… hopefully leave in a few weeks.
They’re 160W. Safe and happy travels!
Here’s my two cents.
This project is very cool. I am extremely interested in the permutations of RV solar installations. The effort you put into venting those batteries and physically isolating them behind plexiglass (presumably if they were to explode) is a great idea. I’m not an engineer so I can’t say you did that the best or worst however it seems most RV manufacturers put little effort into venting corrosive gasses or isolating explosions so minimally I think your setup is probably far better.
The only thing you are doing that I’m leery about is the lack of a fuse coming out of the battery bank. If it were me, I’d have a fuse on the battery terminal appropriate for the wire gauge. If you want to be really anal, you could fuse each battery also. I think the only benefit of that is if one battery dead shorts internally, then you prevent the other batteries from shorting too. Also fusing each battery protects the wire connecting each battery (though unlikely you’d have a problem there).
It looks like for the input/output of the Morningstar you are using AC fuses designed for 120 volts. Again, I’m no engineer and I’m probably just below, at, or perhaps slightly above your level of expertise with this stuff. Do you know for certain you can use fuses like that? I’ve never seen that or heard of that with 12 volt DC applications. But if it is permissible to do that the air conditioner disconnect is a brilliant idea.
Regarding your mystery wires, your schematic suggests the disconnect in the RV is a solenoid? I would think those mystery wires are the input and output to the solenoid. Like if you shut the power off, it has to be interrupted somehow so you need two wires going to a switch, relay, or whatever.
Another fuse thing. So the inverter I presume is a charger for the batteries, right? So if that thing is pumping current into the batteries when you are on shore power or generator, the output of that should be fused too. Though if it has a fuse that’s easily replaceable without tearing apart the inverter/charger then that would not be necessary. Just want to make sure you don’t go off like a flash bulb or I won’t have anything to watch. 🙂
Lastly, on your schematic you marked is as “AC Disconnect”. Don’t you mean “DC Disconnect”? A better label would be solar disconnect.
What are you doing with the original house batteries? Are you abandoning those in place?
You are a gifted human. Love your RV stuff. I’ve learned a lot! 🙂
Hey there Pippi,
I been watching yours and some other videos on off grid solar. I was looking at your solar schematic and noticed that there is not any protection to isolate the batteries if a short happens on the 12V side. The batteries you have can probably dump over a 1000 amps into a short circuit, so you really want to put something thing there inline. Also, you should probably have a battery disconnect switch, to make it convenient to isolate the batteries for working on the 12V wiring. I also just left a youtube comment on the wiring/fuse video about using AC rated stuff for a DC application. You need to make sure that your fuses/breakers/switches are truly rated for a DC. It is much harder to break the arc as the contacts open up separate. I am not sure about the galvanic action from dissimilar metals causing problems with contacts heating up. My understanding that this was more a problem with low voltage circuits and causing voltage offsets and the higher currents and arcing would burn off any corrosion on the contact. It is possible that the AC intended parts are not as critical in the chemical makeup is causing it to build up over time.
FWIW- I am an engineer and have lived through not totally understanding these differences and have had switches and breakers fail because of the misunderstanding between the AC and DC ratings.
Thanks for putting these videos together. You really are showing many people that anyone can do this with a little research and a can-do attitude.
Good tips Andy, thank you!
Hi Pippi – newly registered here – thanks for all the great and well-articulated info on your solar setup.
I’m wondering how that fuse combo is going. 40A between the panels and the MPPT charge controller and 60A between the MPPT charge controller and the batts.
Why 60A from the MPPT to the batts? How did you calculate that? I do not want to go too high over the amp output of the MPPT.
FYI I’ll be running 4 175W panels in series AND parallel (like yours) down 6-gauge cables to a 40A MPPT, then 4-gauge into a 12V batt system (2 6V golf cart batts.) 37.54V and 19A total.
Thank you…
Craig
Hi Craig, it’s for future planning of possibly upgrading in size.
Your videos are SO helpful! I’m trying to plan our PV system and have a couple of questions.
After a few months of research, I thought I had settled on the PV system I want for our small RV. But then, I started (over) thinking loss of power through wires and cables and rethinking my PWM choice. Unfortunately, I can’t find an answer to a few specific questions. Can you help?
*************************
A couple of notes about my set up:
1. Right now, we just use our trailer for weekend trips but we hope to make longer and longer trips — weeks, then months, and then hopefully full time! As we spend more time in the trailer, I’d like the ability to expand our system to about 400 watts (my calculations tell me this should be enough for what we use).
2. Our trailer is a molded fiberglass trailer which are great because they are much less likely to have leaking roofs than a traditional RV. The downside is that the idea of drilling holes into the roof isn’t very appealing AND the roof is very small. Because of these two facts, as well as the desire to take our PV system with us if we grow into another trailer, we want to keep our system “portable” right now. In other words, we do not want to mount panels on our roof. This is important because my plan is to have a long 10 AWG cable running from the solar panel(s) to the trailer.
*************************
A couple of notes about the products I’m considering:
For my research, I have been looking at products offered by one brand just so I can get an apple-to-apples comparison as far as costs go. Here’s a list of the equipment I’m looking at with price and specs. Please note that I left cables and connectors out because that’s going to cost me the same no matter what.
1. Solar panels – $140, 100 Watts, 22.5 V, 5.29 A
2. PWM charge controller – $60, Max solar input 25 VDC, Rated charge current 30 A
3. MPPT charge controller – $120, Max solar input 100 VDC, Rated charge current 20 A
*************************
My plan and my questions:
My plan is to have the charge controller and inverter (not on this list because it’ll be what it is no matter what) in the trailer, connected to our 12 V battery. Ultimately, I’d like to upgrade this one battery to two 6 V batteries. Then, I’d like to run a long 10 AWG cable from the charge controller out to the solar panel(s). How long will the cable be, you ask? Well, it will depend on the camp site. It might need to only be 5 feet but it might also need to be 40 or 50 feet. I know this is where I’ll lose energy due to resistance.
So here are my questions:
1. I was told by the company that the 30 Amp PWM controller can handle 4 100-watt panels (wired in parallel) and my math confirms that. My concern is that in parallel, this set up will produce more than 21 Amps – that seems like a lot for resistance to work on over 30 or more feet of 10 AWG cable.
Using the same math, I figure that I could also use the same 4 100-watt panels wired in Series (90 V, 5.29 A) or in Parallel-Series (45V, 10.58A) with the 20A MPPT charge controller. Am I correct?
My point would be to keep the current (Amps) as low as possible to lessen resistance and then have the MPPT controller convert the extra voltage to more Amps.
2. Is the extra cost of the MPPT controller worth it? It seems like people writing on the topic say that if you have a small system, an MPPT controller is not worth the money but they don’t give any hard evidence of why not. Frankly, I’d think if you’re limited on space, you’re limited on the number of panels you can buy. So, taking that $60 and putting it towards another panel might not be the best option. Plus, since we’ll have some a small system, it seems to me we’d need to have it running as efficiently as possible.
Those are my two questions – can the MPPT 20 Amp Charge Controller handle 400 watts worth of panels and is it worth spending the extra money on it to account for losses associated with resistance?
I’m aware of the fact that I’m probably over thinking this but any suggestions you can give would be appreciated. I’m almost to the point of just going with the MPPT because it’ll give me the option to wire the panels in Series, but sixty bucks is sixty bucks.
Thanks in advance for your help!
Good job planning your own set up! Here are a couple things to think about and consider. Having more arrays of smaller outputs is often better than having less arrays of more. So, I’d recommend using your series and parallel connections. If one panel goes out, it wont bring the whole thing down with it.
Also, having a larger controller than what you need and also using a cable size bigger than required is great for planning for future additions. Go with larger cable at least even if you don’t plan to expand and use copper not aluminum.
PWMs are often used for smaller jobs because it may not matter as much about being as efficient about managing all the incoming power as a larger application that may need the extra management. Smaller systems may also be constantly demanding a small load while the sun is out, for example, a water fountain so less input is wasted. Also, PWMs are better for smaller panel arrays that may only be sending in enough volts to cover a charging of 12 watts, 14-16. If you will send in more wattage than the PWM can manage it could be wasted. Another thing that I’m NOT certain about with PWM, but I know some MPPTs do, is they run the batteries through different cycles applying different voltages for a determined amount of time to most optimally charge the batteries to maintain their best health. No matter what, take note and research the companies and brands. You may fare better with a PWM controller of a good company than an MPPT of a bad company. MorningStar has had good products so far. You can check out Handy Bob’s blog for more info on companies as well as info about all of these topics you’ve had questions on.
Good luck and great job for doing all your research and understanding it yourself! 😀
Thanks so much! I can’t believe I’m just finding your site and videos and just hearing about Handy Bob. Of course, I’ve only been at it a matter of weeks, but there seems to be a lot of weak/bad/inconsistent information swirling around the interwebs these days.
I’m off to Handy Bob’s where I’ll spend the rest of the day binge-reading.
Thanks again!!!
HI PIPPI. LOVE WHAT YOU DO ,IM A CONTRACTOR/CARPENTER I CAN PRETTY MUCH DO ANYTHING IN CONSTRUCTON BIULD REPAIR ,,ETC,I STLL CANT GET SOLAR SYSTEM ,I BOUGHT 6 ACRES. LIVING OFF GRIDB I SEE HOW YOU BIULT YOUR SOLAR PANNELS .IM TRYING TO BUILD 1 FOR MY RV.I HAVE A GENERATOR ITS KINDA LAUD AT NIGHT .MY BOXER HATES THE SOUND OF THE GENERATOR.ILL WILL TRADE YOU MY LABOR FOR YOUR LABOR. ..IM NOT VERY GOOD AT BUILDING SOLAR PANNELS. AND HOW IT REALLY WORKS IM JUST LEARNING ,AND WHERE CAN I GET PARTS TO BUILD 1, THANKS
Hello Pippi,
I see you have what looks like two giant batteries in you RV, what size are they? How many batteries do you have in that bank?
Hello Pippi,
Sorry, I just looked at your drawing and see that you used 4 batteries for your bank. Are they 6v batteries each and what is the amp hour on those?
Thanks