diy solar

diy solar

Best system for RV

gelling

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Feb 28, 2022
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I have a 44' RV 5th wheel with 50A shore input and onboard 5.5kw generator. I started putting a material list together for an off grid power system thinking I'd do what I see everyone else doing... 12v battle borns, 200w panels, victron charge controller and multi plus ll inverter...etc.
After researching more I'm thinking there's a better way... like 24v or 48v, sever rack batteries, all in one growatt inverter/mppt/solar charge controller... thoughts suggestions?? TIA.
 
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Power requirements will rule this build. My 35’ fifth wheel uses nearly no power in the cooler months. When the propane heater blower motor comes on, the power requirements go up a lot.

If you want to run a single air conditioner, that is even more power. Will says in one of his videos for an RV air conditioner you need to fill your roof with panels and then have just about as many panels on the ground.

In my signature block, I have two links to my RV build. I now have what may be enough solar to run a single 15 K BTI rooftop air conditioner 6 hours a day, but am waiting for warmer weather to try it.
 
Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the PVwatts.com or JCR Solar Uber-Sun-Hours calculator sites to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that. If you're looking at the All-In-Ones check for correct voltage outputs (120v or 240v Split Phase for North America, 220v Single Phase for European type areas) and make sure it has enough capacity for a little bit of growth and fudge factor.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. :) Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen 3000AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round :) ) and help figure out which parts and pieces you're going to want to get.
 
Don’t know if the server rack systems are built to be installed in dynamic environment. Hybrid function of the multiplus has been very valuable.
 
“Best system”

The best system is the one that works- for you.

You need four things to begin to determine that:
1) do you want a starter system that’s expandable, or all at once?
2) how much money can you spend?
that’s not a joke; $5000, $1000, $10,000 let’s you pick and choose wisely after developing the next two answers
3) what is the daily watt-hours that your camper uses? Total for everything.
4) what are the total watt-hours for everything minus air conditioning, electric hot water, and fridge?

If 3 and 4 can be determined for daylight and after sunset for each- even better.

Then you can figure out the battery storage required to meet your needs- and adjust for how long. Then you will also know the inverter power required and the amount of panel wattage to recharge, plus have a good idea of how to determine how much or little you need/want the generator to run.
 
The problem with doing an RV at 48 volts nominal is finding a decent buck converter to power the legacy 12 volt distribution panel.
If you have high draw dc stuff like slides its even more of a challenge.
What is the amp rating on your legacy ac2dc converter?
Do you have high draw slides/jacks/levellors etc?
 
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The next problem is getting enough pv panels on the roof to keep up with consumption.
The more things that are already on the roof the more challenging it gets.
Not only do all those things take up roof space but the little shadows they cast can really interfere with production.
 
I went from living in a 2400sf home down to full time living in a 400+sf 5th wheel RV and have come to appreciate living without so much stuff. I have seen many people purchase large battery banks and solar arrays and yet see them always use shore power and hardly ever use the $10,000 worth of stuff they thought they needed.
So the Best System is one that you are going to actually use.
Energy Audit is mandatory. Do you really need to run the coffee machine, toaster and the hair dryer at the same time? You already have a generator so could you use that for those occasional times when you do need more power? Do you need to run the A/C off battery?
My personal needs are few these days and I rarely need more than 2-3 kWh of power on a daily basis so my best system may be different than yours and your best system is personal to your requirements. Until you can find out what your needs are, it will be difficult to answer that question, unless money is no object.
I see you suggested Battle born batteries so money must not be an object. I didn’t know people were still buying those things. I thought only those YouTubers that got them sponsored we getting them.
 
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Most of the questions you have, I went through when building my RV. You can check out the link in my sig to see all the problems I had to overcome.
 
rarely need more than 2-3 kWh of power on a daily basis
I’m full time ‘stationary’ and I see that as very reasonable. I don’t use that much most of the time. Except for winter with the constant 3A 12V furnace fan- it’s not much but adds up.

You can ‘compromise’ a few things that aren’t really compromises- they’re just behavior changes- and not miss anything ‘normal.’
 
I also live full time stationary in a 42' 5th wheel.
Just beginning to assemble all the components I've collected through the winter months.
I have extra roof space with a 22' cargo trailer/rolling shop that allows for a total of 6KW of PV.

Most of a large front pass through compartment has been consumed by batteries, inverters and charge controllers.

We're planning on around 15kWh most days and need only the occasional shore power. It will be 3x higher than that during the hottest 3 months of summer and the PV system won't be able to keep up.

There's 15kWh of 48V batteries on-board. 6KVA of inverter. The 12V system is left mostly intact including the 12V batteries and we have a 250 gal propane tank on site and a wood stove.

For us, it seems perfect. Probably not for others.
 
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I also live full time stationary in a 42' 5th wheel.
Just beginning to assemble all the components I've collected through the winter months.
I have extra roof space with a 22' cargo trailer/rolling shop that allows for a total of 6KW of PV.

Most of a large front pass through compartment has been consumed by batteries, inverters and charge controllers.

We're planning on around 15kWh most days and need only the occasional shore power. It will be 3x higher than that during the hottest 3 months of summer and the PV system won't be able to keep up.

There's 15kWh of 48V batteries on-board. 6KVA of inverter. The 12V system is left mostly intact including the 12V batteries and we have a 250lb propane tank on site.

For us, it seems perfect. Probably not for others.
These usage stats are right on par with mine as well. About 15kWh per day, sometimes less, and 50-55ish kWh in the summer months with 105-115* weather. The 3x ACs really are a killer.
 
I also live full time stationary in a 42' 5th wheel.
Just beginning to assemble all the components I've collected through the winter months.
I have extra roof space with a 22' cargo trailer/rolling shop that allows for a total of 6KW of PV.

Most of a large front pass through compartment has been consumed by batteries, inverters and charge controllers.

We're planning on around 15kWh most days and need only the occasional shore power. It will be 3x higher than that during the hottest 3 months of summer and the PV system won't be able to keep up.

There's 15kWh of 48V batteries on-board. 6KVA of inverter. The 12V system is left mostly intact including the 12V batteries and we have a 250lb propane tank on site and a wood stove.

For us, it seems perfect. Probably not for others.
How will you charge/float the legacy 12 volt batteries?
 
How will you charge/float the legacy 12 volt batteries?
I'm going to begin with a Victron IP22 smart charger. Leaving the OEM converter in place but disconnected in case the Victron proves insufficient to keep them charged. It's a 65amp converter and consumes almost 1000 watts.
The Victron is only 30amps so it may be insufficient.

Going DC->AC->DC is not the most efficient conversion but I've yet to see a buck converter work well and most everyone eventually installs a 12V battery for the high amp loads of jacks, slides, ext.
 
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I'm going to begin with a Victron IP22 smart charger. Leaving the OEM converter in place but disconnected in case the Victron proves insufficient to keep them charged. It's a 65amp converter and consumes almost 1000 watts.
The Victron is only 30amps so it may be insufficient.

Not the most efficient conversion but I've yet to see a buck converter work well and most everyone eventually installs a 12V battery for the high amp loads of jacks, slides, ext.
This is about the best 48->12 dc2dc solution I can find.
Orion-Tr48/12-9 (110W)
It would keep the lights on but not a whole lot more.
Victron, Samlex and/or Sterling should address this issue as more RVs go to 48 volts.
 
These usage stats are right on par with mine as well. About 15kWh per day, sometimes less, and 50-55ish kWh in the summer months with 105-115* weather. The 3x ACs really are a killer.
I only have 2 ACs but they worked their ass off last year. Last summer was brutal here.
 
Victron, Samlex and/or Sterling should address this issue as more RVs go to 48 volts.
I've lurked around here for a couple years now. Originally thought I'd go with a 24V system and actually built a small test system for the cargo trailer with a LV2424.

But 48V does seem to be the coming thing.

Form factored into the decision as well. Having the necessary space for an install is no trivial matter.
 
I've lurked around here for a couple years now. Originally thought I'd go with a 24V system and actually built a small test system for the cargo trailer with a LV2424.

But 48V does seem to be the coming thing.

Form factored into the decision as well. Having the necessary space for an install is no trivial matter.
Another benefit of a 48 volt core is...
The core system doesn't need to be so proximal to the ac/distribution panel because the dc voltage drop is much less of an issue.
 
is about the best 48->12 dc2dc solution I can find.
Orion-Tr48/12-9 (110W)
It would keep the lights on but not a whole lot more
Having “lived on” 12V for the past few years MY thought would be to split the big-amp stuff to one system and install a 12V AIO and 400W of solar to another independent system with just a few lead or one or two LiFePo 100Ah batteries.

Almost a year ago I planned to upgrade from my 200W to 400W scaleup into 800W total, but decided to play for a bit with 400W in different facings, series, a parallel try, a 600W try… but the 400W facing two different compass points and the mppt upgrade from pwm ran my fridge and everything else on six lead batteries so well that I wound up leaving it (lazy) ….then fall came with it’s 5 or 7 cloudy days in a row thing… not so good. But I’m in Vermont.

So a 400-600W separate system solves two concerns: 12V, and maybe electing to not use generator power overnight cuz the tv, lights, and fridge could live independently.
 
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