Bought a new Fifth Wheel, want to go solar

[UrbanElite]

Hey everyone, I’m been browsing around the forum and YouTube for some info on Solar and Rvs. We have full time camped in our Enclosed trailer that we built into a toy hauler for camping/hauling our toys there. I built a solar set up for the unit using 2x320 watt panels, 40 amp tracer and 2x 320 AH Trojan battery’s. The system has worked great for running our mini fridge 24/7, lights, phones anything we needed to power off our 1500 Pure sine watt inverter. I was super impressed how well the solar worked because all we do is boondock!

Now we finally upgraded to a big fifthT wheel toy hauler, it has a built in Oman 5.5 generator, from what I read these are one of the best you can get for rvs. But even though we have it I didn’t want to listen to a generator before and don’t want to now. So the research I’ve done my only concern is the wiring into the trailer. I see you wire your system how you would normally. Panels to controller, controller to batteries , batteries to inverter, obvs fuses, breakers ect... But I see you have to tie the inverter into the rv ( auto switch/converter ) where all the breakers, fuses ect of the trailer are.

Now I see there is some options In different inverters for rv that aren’t just your standard inverter. You’d run your cables off your batteries to this inverter and than you have 4 other parts to go into your rv section. I know some use normal inverter and wire it to one plug into the trailer, but we want our whole trailer to run off our batteries. I’ll probably put those 2x 320 amp batts back in our fifth wheel and add another set to go with them. Just want to be able to charge a phone in our bedroom or use any plug in the trailer!

Just wondering if some people can chime in to how they wired their rvs and what parts they used. Thanks!

[Mike90250]

Before you get carried away with batteries, what are your loads going to be ? Will the 5th wheel nearly always be attached to the tow vehicle ?
Put the batteries and inverter in the truck bed?

[ewarnerusa]

We use the old "manual" transfer switch, its easy and fool proof. We strictly boondock and we just plug the normal shore power cable directly into the inverter 120V AC outlet. The camper is then fed with 120V AC from the inverter exactly like it would be if plugged into shore power or generator, all outlets are live. It is critical you disable the onboard 12V DC converter when you do this, otherwise you create a power draining loop. WE put the converter's 120V AC power supply on its own AC breaker in the panel which we use as a power switch for the converter, we switch it off when plugged into inverter. You also need to be aware of potential AC loads that will be too much for your inverter/battery setup to supply such as air conditioner or microwave or water heater on electric. Don't use those, or switch their AC breakers off as well. Switch refrigerator over to propane as well.

[UrbanElite]

Before you get carried away with batteries, what are your loads going to be ? Will the 5th wheel nearly always be attached to the tow vehicle ?
Put the batteries and inverter in the truck bed?

I already have 2x 320 AH V6 battery’s for my last build that I’m going to use. Looking to mostly run the plugs in the trailer for small electronics and hopefully run the fridge as that’s what I built my last set up was for. We have the built in generator for bigger loads too.

not looking to build or Mount anything in the truck box. Want this to be contained to the trailer

[UrbanElite]

Thanks for the reply! Everything you said makes perfect sense! There is a few good YouTube videos I’ve been watching explaining the solar system on an RV, not overly complicated but littles like switching the converter off I see a lot of people miss and it drains their battery’s!
I would like to do an auto transfer switch and hard wire the inverter into the trailer, but I might just unplug/turn off the rv converter and plug into the inverter from the trailer to test and play with the system before hard wiring it

[chrisski]

I am nearing the end on my RV build, my first real solar project.

For some of the DC wiring, I am adding some DC charging ports https://www.amazon.com/dp/B07PN5YZX3...v_ov_lig_dp_it and also a separate fuse box for them. Since I may upgrade to 24 VDC in the future, I am hooking some dual voltage accessories to this fuse box. I have the separate fuse box for some higher voltage DC items. These USB charging ports don't get their full potential unless they are 24 volts, but I will still need to keep the rest of the trailer on 12 VDC which it was designed for.

I don't have the built in generator you do, so makes the wiring a bit easier. Mine is a 2.3 kw continuous inverter generator by Craftsman. I pull it out and turn it on and off for higher loads. At some point, I'd like to add a generator to run the A/C, but that will be with the next RV.

[UrbanElite]

The goal would be we could run everything we need off of solar even our fridge would be nice. Our last solar build I ran a oversized mini fridge with freeze, and these trailer we opt for the single fridge as we don’t need a double, we only boondock, so I doubt this fridge takes much more power than that other one. Other than that it’s mostly charging phones, cameras, led lighting inside and outside. For the most part our power consumption is pretty min. We do have the generator for back up, most people are just telling me to run it, but it’s nice not having to listen to generator, spend money on the gas, ect...

[Wrybread]

I have a very similar system except I have 3 320-watt panels. I live almost fulltime in my RV off-grid on the Northern California coast (I'm a camp host at a campground) with 4 Trojan T105's wired for 12 volt (I should really redo them for 24 volt), which I think gives me a capacity of 450 amp hours or my preferred way of measuring is 5400 watt hours, and I almost never get low on power. I wish more campers here would install intelligent solar systems as you're doing! Too many people here rely on their generators, which are unbelievably noisy, stinky, hard on batteries, and because of quiet hours leave them in the dark after 9pm. So silly. So kudos to you sir.

Reading this thread my only suggestion would be to consider adding more panels, since you have the room and they're dirt cheap. Or at least plan for their possible addition in the future. A great thing about over paneling is that, for one thing, since our panels are flat mounted (I'm assuming yours are) we lose ~15% of power off the top. And having extra panels means we're still getting significant charges on cloudy days. If you have the roof space, I'd recommend it, it's worked out great for me.

That said there's a couple of considerations:

- if you have more than two parallel panel banks (1 non series'd panel is a "bank", as is 2 or more series'd panels) you need to put fuses on each bank. Easily done I can post links if you need.

- your charge controller needs to be able to handle the panel voltage. I used to have a Tracer and it was 100v, which wouldn't let me do 3 panels in series, so I wired my 3 panels in parallel with fuses. I've been really glad about that decision since I frequently have partial shade or a kayak covering one of my panels.

- and of course your wiring needs to be beefy enough to handle the max power your panels might put out. I'm a big fan of overly fat wire since the primary issue with wire throws is the labor and penetrating the RV, not the expense of the wire itself. So I use 8 gauge.

I'm subscribed to this thread, glad to chime in if you have any questions.

Edited to add: one thing that strikes me is your fridge: if this is one of those propane/AC/DC fridges it might not use a compressor, and might use a bunch of power when running off electricity. You might want to test it's power consumption and duty cycle (how long it stays on). Long ago I rigged up a system to power my RV fridge once my batteries were fully charged, and it was a losing battle since that fridge was so inefficient when running off power. Since you mention successfully powering a fridge off solar in the past you might want to look into any differences between this fridge and your last.

[UrbanElite]

Thanks for the Reply Wrybread, I just like the idea of solar because you don’t gotta worry about running the generator, filling it with gas, its free power in the long run and its cool to just be able to boondock without worry about power on your mind. I will appreciate all the help I can get. I want this system to be solid, build right and last the test of time. We really splurged on this trailer, hoping to keep it for a long time and want it to be done right the first time and done well.

I’m looking to put in my 2x320 AH 6 Volt battery’s into the trailer to start and go out on a few trips and see what power consumption is like first, do some testing. I will watch our battery voltage thru the process and use the generator to recharge the batteries to start, hopefully see what we need power wise to size the system right. Mostly all we are going to use power for is being able to use the 110v plug for phones, little electronics and such, no massive loads.

I’m hoping to reuse as much of my old solar system as possible, the 2x 320 AH 6V Batteries, my traccer charge controller, 2x 320 watt panels etc... But whatever I need to make the system work I will get. I’m hoping to wire my panels in Parallel as that what’s on my current set up. I like this way I can park anywhere and not have to worry about shading in my panels.

I agree on over killing the wire, as like you said your penetrating the RV. I will definitely put in more gauge than needed for this fact of never having to worry about over powering that wire.

As for the fridge I will have to do more testing and research on this topic when I get the trailer this spring. Our last fridge ran 24/7 but it was just your standard 110v bar fridge with a small freezer on top. This being an RV fridge is different for sure. I’m not sure if I’m dreaming on running it on electricity or not, just would like to cut down on propane use. We searched high and low for the right trailer that had both Gas and electric fridge single fridge. A lot of these big toy haulers have massive double fridges that only run off the generator.

Most of my questions come from wiring the RV its self and joining the solar system to the trailer. Ive found 2 really good videos that explain how you need to tie into your breaker panel, shutting off the trailers converter so you don’t have a power loop in your system and the auto transfer switch. Now from what I’ve seen there is 2 ways to do this.

1- Buy a new auto transfer switch that you replace yours with. Has wiring that goes to the investor, for shore power, generator etc....

2- Buy an inverter that has an auto transfer switch and converter wired into it.

Iike said up top and seen other videos on it as well, but just running a cable from your shore power to your inverter and shutting off your converter works well too, but I might do that to start when I start building the system and testing purposes, but long run I wouldn’t mind hard wiring it in. All of this is going to be hard to say until the trailer arrives this spring and we go out on a few trips to test out the trailer, how those battery’s do etc...

[ewarnerusa]

An absorption fridge uses very little propane while operating. The flame it uses to boil the ammonia is like a big candle, you can view it from the back of the fridge by removing the outside panel to check it out. So while it is not zero, it is not a big drain on your propane like the furnace or water heater are. What I would imagine as a good way to use excess solar is using a load function from a solar charge controller to divert excess current to a water heater element. I would think that could offset some propane use and you would have the smug satisfaction of every amp of solar harvest going towards something. I remember reading about a guy doing that in a truck camper setup many years ago on rv.net but I never kept up with it.

[Wrybread]

An absorption fridge uses very little propane while operating. The flame it uses to boil the ammonia is like a big candle, you can view it from the back of the fridge by removing the outside panel to check it out. So while it is not zero, it is not a big drain on your propane like the furnace or water heater are

I agree in principle since the flame is so small, but in practice I've found that mine seems to use about 3 to 5 gallons of propane a month, with opening and closing of the fridge. It's definitely possible that my fridge isn't as efficient as some.

What I would imagine as a good way to use excess solar is using a load function from a solar charge controller to divert excess current to a water heater element. I would think that could offset some propane use and you would have the smug satisfaction of every amp of solar harvest going towards something.

Totally agreed. A few years ago I made a Python script for a Raspberry Pi (for those who don't know, that's a small Linux computer) that would power my fridge from AC after my batteries were in float for a little while. That would in theory do two things: the biggie was 1) since I wasn't at my camper every day it would preserve things in the fridge if the propane went out for some reason, and 2) if the propane went out for some reason it would relight when the AC turned back off. But in practice in didn't do either very well, ha. I've always meant to revisit the issue though.

Heating water is a good idea, though solar heating water directly is probably more efficient. Other than those little roof showers, I don't think I've ever seen RV solar water heating, oddly enough.

Most of my questions come from wiring the RV its self and joining the solar system to the trailer. Ive found 2 really good videos that explain how you need to tie into your breaker panel, shutting off the trailers converter so you don’t have a power loop in your system and the auto transfer switch. Now from what I’ve seen there is 2 ways to do this.

There's also #3: remove the fuse for the charger when you're not plugged into AC... Works great in a pinch.

Funny story: a friend bought a 5th wheel that was outfitted by the previous owner with a mix of really good equipment and really bad knowledge of how to use it. There was a 12 volt battery bank and a 36 volt bank, and the previous owner explained how you couldn't leave the AC power on for very long since it would kill the 36v bank. Turns out it was powering the charger for the 12v bank, every night for years. And the 36v bank was made of big fancy batteries, which were now physically warped from all that rapid discharging. Was pretty hilarious. My friend wound up just pulling the fuse to the charger since they never charged off AC, and that worked for them for years. But of course it gets more complicated if you want the option of AC charging.

Sounds like you're very thoroughly on your way, psyched to read about it as it takes shape.

[UrbanElite]

There's also #3: remove the fuse for the charger when you're not plugged into AC... Works great in a pinch.
Funny story: a friend bought a 5th wheel that was outfitted by the previous owner with a mix of really good equipment and really bad knowledge of how to use it. There was a 12 volt battery bank and a 36 volt bank, and the previous owner explained how you couldn't leave the AC power on for very long since it would kill the 36v bank. Turns out it was powering the charger for the 12v bank, every night for years. And the 36v bank was made of big fancy batteries, which were now physically warped from all that rapid discharging. Was pretty hilarious. My friend wound up just pulling the fuse to the charger since they never charged off AC, and that worked for them for years. But of course it gets more complicated if you want the option of AC charging.
Sounds like you're very thoroughly on your way, psyched to read about it as it takes shape.

- Yeah once we get our trailer this spring and do some testing with our batteries in I will slowly update the forum with info I find and my project progression. What are you running for a inverter in your system? How is yours tied into your system with wiring into your breaker panel, auto transfer switch etc...

[chrisski]

If the 320 AH 6 volt batteries you are thinking of buying are lead acid, upgrading a battery bank is not wise. They get weak and the new ones do a whole lot of extra work to make up for it.

For me 458 AH is good. That will allow me to run for at least 2 days. My biggest draw is the fan for the propane heater. If I don’t use the heater, I will probably last at least 5 days. I would get 10-15 amps for a couple hours from 1000 watts of panels on a cloudy day. I am halfway done installing another 350 more watts to the roof, mostly for cloudy days.

I found recently my propane fridge uses an insignificant amount on a two or three day stay. My first measurement was a gallon a day, but I’m sure something else used up that propane. When I turn it on electric, it pulls 26 amps from my batteries and 330 inverter watts. I don’t know how these fridges work, and I want it to remain a mystery, but they sure are quiet.

[UrbanElite]

If the 320 AH 6 volt batteries you are thinking of buying are lead acid, upgrading a battery bank is not wise. They get weak and the new ones do a whole lot of extra work to make up for it.

For me 458 AH is good. That will allow me to run for at least 2 days. My biggest draw is the fan for the propane heater. If I don’t use the heater, I will probably last at least 5 days. I would get 10-15 amps for a couple hours from 1000 watts of panels on a cloudy day. I am halfway done installing another 350 more watts to the roof, mostly for cloudy days.

I found recently my propane fridge uses an insignificant amount on a two or three day stay. My first measurement was a gallon a day, but I’m sure something else used up that propane. When I turn it on electric, it pulls 26 amps from my batteries and 330 inverter watts. I don’t know how these fridges work, and I want it to remain a mystery, but they sure are quiet.

Yeah they are lead acid and your right, that thought flew over my head. I’m not going to worry about the fridge from now from what I see they are pretty efficient on propane. Just going to worry about getting power to the outlets for electronics like charging phones, the stereo outside, tv etc... How are you tied into your system with your inverter, auto transfer switch etc.. What route did you go?

[chrisski]

How are you tied into your system with your inverter, auto transfer switch etc.. What route did you go?

When I am using my inverter, I shut off the converter by tripping the AC circuit breaker by the door. This prevents the battery from trying to charge itself through the AC to DC converter that the 50 amp jack normally uses. When I'm boondocking, the only time I ever turn that converter breaker on is when I unplug the inverter, turn the generator on and plug that in so the DC Converter can give the batteries some charge after cloudy days. I found out the OEM DC to DC converter in my trailer provides 15 amps and if I run this for an hour or two and let the panels recharge the battery bank the rest of the day, I'm at 100% state of charge by night.

Unless its freezing outside and my propane heater fan is running constantly, I think I have enough power to last me up to five days. If I use the coffee maker, it'll be between 10 am and 2pm, and I found my panels are pushing 10 to 15 amps on a cloudy day, which doesn't take long to recharge my 55 amp coffee maker that runs for three minutes.

I did forget to trip the circuit breaker once with the inverter on, and I think the AC to DC converter pulled about 700 watts trying to charge itself, and I heard a clicking from the battery, which I think was the trailers self-resetting breaker. I have a plan to build an auto shut off for the DC to DC converter I got here How To AUTOMATICALLY Disconnect a Converter Charger When Using an Inverter - YouTube. For now, I'm just counting on not shutting the converter off.

For my high wattage loads, which is pre-dawn or night time electric K-Cup coffee maker (55 amps) or the microwave (155 amps), I manually unplug the inverter from shore power and plug in the generator by walking outside. I bought a 50 amp trailer plug in with a 15 amp regular house plug that is about 12 inches long and makes the job easy.

I do want to make these trips as easy and enjoyable as possible, so I'm looking at upgrading to 24 volts and going with 50% more battery. With the higher voltage and bigger battery storage, I think I will have the watthours to run the microwave for 20 minutes a day. I just added 350 more watts of panels to my roof which will bring the roof to 950 watts, with 400 watts of portable panels, and I think that will be enough panels to charge a 24 volt battery bank for my power usage. My next trip will tell for sure if I have enough panels. If I do go to 24 volts, I would get rid of my lead acid batteries and get lithiums.

I am looking at air conditioning, and automatic transfer switches, but there's not a lot of builds out there I see. One guy was able to do it, but what he had trouble with is both ACs on at once and the transfer switch goes from solar to generator, he'd blow the battery fuse. I'm probably 5 years away from solar powered Air Conditioning.