New RV Owner looking to add Solar

pbennison

Member
Hello Everyone,

My wife and I bought a 2017 Wilderness 3175RE last August. I would like to add some solar capability. I was thinking of adding an additional 12V battery, run in series for 24V and some solar panels. Couple questions.

Do these come with some type of inverter?
Do I need to purchase an inverter even if there is one?
Should I stick with 12V and run batteries in parallel?

We do not plan on doing a lot of boondocking or anything. I just want the ability to run power without having to run my 2000W portable generator.

Any advice, suggestions, etc. would be much appreciated.
 

jbeletti

Director of Owners Interests, Heartland RVs
Staff member
Your coach will not come with an Inverter. It will come with a Converter (converts 120 VAC to 12 VDC).

Doing a 24-volt system is efficient and allows for smaller gauge wiring in that DC system, but you will need to add a 24V to 12V converter for running your coach (lights, water pump, water heater and furnace control circuits, jacks etc.). For your smaller setup, I'd stick with a 12V system and wire multiple batteries in parallel.
 

pbennison

Member
Your coach will not come with an Inverter. It will come with a Converter (converts 120 VAC to 12 VDC).

Doing a 24-volt system is efficient and allows for smaller gauge wiring in that DC system, but you will need to add a 24V to 12V converter for running your coach (lights, water pump, water heater and furnace control circuits, jacks etc.). For your smaller setup, I'd stick with a 12V system and wire multiple batteries in parallel.

Thank you. That makes sense.
 

centerline

Well-known member
I agree that 12v solar array is the best... and no converter or inverter is needed for a 12v system. but you WILL need the solar controller, preferably an MPPT type, but they also have micro controllers now that connect to each panel separately.... I dont have any actual hands on experience with the micro controllers, but they sound like an easy way to go....

you are correct that if you have solar, you should have a battery bank big enough to maximize the system for the size of array you install...
there is such a thing as TOO many batteries for a given amount of solar capacity, so size it accordingly... which can only be done by knowing what your average daily amp consumption is, how much uninterrupted, unshaded sunlight the panels will get during the day, and the number/wattage of the array....

here in the northwest, I figure 8hrs of sunlight per day, and size the wattage of the system to twice what you require....

solar is by far the best way to create power for your RV (or boat), but the panels are rated in a temperature controlled lab, connected to a meter while they "short circuit" the panel... and the watts created in this manner is how they rate panels.... you will never see this figure in real life except under perfect conditions, using an MPPT controller, which the MPPT technology can take the output of the panels and boost it to create more input to the batteries than it would get by using any other type of solar controller.

so, in prefect laboratory conditions, a panel that is rated at 200watts has a theoretical potential of about 14amps.... but in real life, you will get a daily average of about half of this (usually a bit more), which is a good number to go by when figuring your system unless you never leave the warm sunny states.... when the system creates more power than the average number that you used, its a bonus, but when the sun is behind the clouds, or there is not as much sunlight per day, you should still be producing close to or slightly more than the number you came up with when sizing the system at 50% of its "stated" rating..... which would then be called 100% of the number you "engineered" your system to deliver on daily average...

the time and cost is in the wiring and the initial cost of the controller, wiring, framework and whatever else is needed, so as long as the space is available on the roof, doubling the size of the output is only a matter of the cost of a second panel, because everything else will have to be installed to run the first panel, and the second one and third one can be wired in, providing the controller you use is big enough to carry the load..

solar panel power is simple, clean, trouble free and with a long life expectancy, but if its undersized for your needs, you wont be much impressed with it, but if you have all the power you need because you installed a system that is big enough, no one will ever hear you say how you wished you would have installed a smaller system....

ive installed solar on my last three boats, and installed a system in a remote cabin for a friend, which both types of installation require that the system be able to support the needs that it was installed for, more so than an RV would, where you can either start the generator, plug into a post, or start the tow vehicle to get power restored into the batteries....
 

danemayer

Moderator
Staff member
If you intend to run any devices that use 120V AC, such as microwave, coffee maker, most TVs, etc., you will need an inverter to convert the 12V output of the batteries to 120V AC.
 

pbennison

Member
I would say that 90% of our travel consists of going to an RV park and connecting to power. I have a small very quiet generator (2000W). My goal for this is to have a system that I can use the microwave, watch TV and maybe brew a pot of coffee without hooking up the generator, if for some reason , no sun, etc. I can connect the generator. I believe I will stick with a 12V system along with a 12V inverter and MPPT Controller.

- - - Updated - - -

I agree that 12v solar array is the best... and no converter or inverter is needed for a 12v system. but you WILL need the solar controller, preferably an MPPT type, but they also have micro controllers now that connect to each panel separately.... I dont have any actual hands on experience with the micro controllers, but they sound like an easy way to go....

you are correct that if you have solar, you should have a battery bank big enough to maximize the system for the size of array you install...
there is such a thing as TOO many batteries for a given amount of solar capacity, so size it accordingly... which can only be done by knowing what your average daily amp consumption is, how much uninterrupted, unshaded sunlight the panels will get during the day, and the number/wattage of the array....

here in the northwest, I figure 8hrs of sunlight per day, and size the wattage of the system to twice what you require....

solar is by far the best way to create power for your RV (or boat), but the panels are rated in a temperature controlled lab, connected to a meter while they "short circuit" the panel... and the watts created in this manner is how they rate panels.... you will never see this figure in real life except under perfect conditions, using an MPPT controller, which the MPPT technology can take the output of the panels and boost it to create more input to the batteries than it would get by using any other type of solar controller.

so, in prefect laboratory conditions, a panel that is rated at 200watts has a theoretical potential of about 14amps.... but in real life, you will get a daily average of about half of this (usually a bit more), which is a good number to go by when figuring your system unless you never leave the warm sunny states.... when the system creates more power than the average number that you used, its a bonus, but when the sun is behind the clouds, or there is not as much sunlight per day, you should still be producing close to or slightly more than the number you came up with when sizing the system at 50% of its "stated" rating..... which would then be called 100% of the number you "engineered" your system to deliver on daily average...

the time and cost is in the wiring and the initial cost of the controller, wiring, framework and whatever else is needed, so as long as the space is available on the roof, doubling the size of the output is only a matter of the cost of a second panel, because everything else will have to be installed to run the first panel, and the second one and third one can be wired in, providing the controller you use is big enough to carry the load..

solar panel power is simple, clean, trouble free and with a long life expectancy, but if its undersized for your needs, you wont be much impressed with it, but if you have all the power you need because you installed a system that is big enough, no one will ever hear you say how you wished you would have installed a smaller system....

ive installed solar on my last three boats, and installed a system in a remote cabin for a friend, which both types of installation require that the system be able to support the needs that it was installed for, more so than an RV would, where you can either start the generator, plug into a post, or start the tow vehicle to get power restored into the batteries....

I would be interested in hearing about the remote cabin. Ironically, we recently purchased a cabin with no grid electric (~$75,000 to get it). In my research to design something for the cabin, it struck me that I could do something similar for our RV.

The cabin is small with a wood stove, propane heater, propane refrigerator and I plan to install LED lights. My plan is to have an off grid solar generator system with backup gas generator. I ran the power consumption calculator and estimated that I will use approximately 2000WH/Day. I have added a factor of 25% for a total of 2500WH/Day. I have spent the past couple months researching forums and below is what I have come up with. I would appreciate any and all advice. Plan would be to use the cabin during the spring, summer and fall. As with the RV, I do not intend to be completely dependent on solar as I have two gas generators.

2500WH/Day
2 Days Autonomy
48V
4 250W Solar Panels
30A/48V Controller
3000w Inverter/Charger
 

pbennison

Member
Your coach will not come with an Inverter. It will come with a Converter (converts 120 VAC to 12 VDC).

Doing a 24-volt system is efficient and allows for smaller gauge wiring in that DC system, but you will need to add a 24V to 12V converter for running your coach (lights, water pump, water heater and furnace control circuits, jacks etc.). For your smaller setup, I'd stick with a 12V system and wire multiple batteries in parallel.
Finally getting around to installing a parallel battery with a solar panel(s). I can fit two on the roof, but, not sure if I need two.

My questions/advice requests.
1) Does this look like a feasible solution?
2) I was hoping to use Unistruts to install panels on the roof. I have no idea if I can install them and/or how to install them. What would be the recommended method to install panels to roof? Are there joists or studs I need to locate?

(2) 280W solar panels (below are specs).
Link to MPPT Controller I am planning to purchase.
Approximately 77 inches X 39 inches.

1625659646732.png
 

taskswap

Member
I've never heard of these panels. But if you hook them to a charge controller and a load on the ground, before installing them, and they produce power, they're probably going to at least work for awhile. A bird in the hand...

I've never used Unistruts. I just use the "Z Clips" you find on Amazon. Those worked really well for my last two installs, so I'd say Unistruts are fine... just overkill...

It's helpful to locate studs but not always required. When I installed my brackets there were two that couldn't hit a stud. I had dicor under the bracket, dicor on top, and eternabond on top of all THAT. That plus the two screws I ran into the luan roof decking (my last camper didn't even have a walkable roof at the time, so this was probably 1/16" luan over foam) easily held those panels down. Those panels are HEAVY and they aren't airfoils. Give them a reason to stay, and they will.

You linked to the EPEver 20A. I had really good luck with the same product in the 30A version in my last install. It worked really well, and got great reviews from folks like Will Prowse on Youtube, mainly for things like mechanical connection strength. I only used it for a year before selling that camper but if that means anything, I think it's a good choice. My next install will be another EPEver. I just wish the remote display was nicer. It's pretty basic....
 

pbennison

Member
Sounds good. I just ordered Z Clips, Dicor and Eternabond. I ended up ordering this for my controller. I was going to mount the charge controller in the storage area directly behind the battery tray behind the propane tanks. I figured 6 AWG wire would be sufficient to go from my controller to batteries (2 - 12V in parallel).

Please forgive my ignorance but I have a couple more questions.

Will the charge controller work when I am hooked up to my truck or connected to 30A at a campsite?
Do I need an on/off switch?
 

taskswap

Member
I had that exact unit in my last camper and it worked well for me. So a data point of 1. :)

The charge controller's function depends on how you wire it. The EPEver has three connections: solar input, battery output, and load. If you put ALL your loads on Load then it's "in control" of the entire system. This lets it monitor battery usage, but IMO this is much more difficult to wire properly into an existing RV because we have all those extra things like AUX inputs from the tow vehicle, 120V->DC charge controllers in our power centers, etc. You have to do a lot of rewiring for that to work. Totally my opinion but I don't think it's worth it for the "upgrade an existing RV system" path.

I personally didn't wire anything to Load at all. Solar goes to the solar input, and the battery output goes right to your main 12V bus. I have a fuse on the solar panel wires as near to the panels themselves as possible (I use an inline MC4 style fuse holder), and a battery switch just before it gets to the EPEver. You don't really need to "turn off" the EPEver in general use, it's just very helpful to be able to do when working on your electrical system. You always want to be able to completely turn off all power in your RV, and if you just hook the solar straight in you can't do that - you'll be hot any time the sun is shining.

Fuses protect wires not devices. There's a great chart here:

For 6AWG with a moderately short run looks like you'd want a 40A max fuse. But since the EPEver you bought is 30A I'd probably go with that to be safe.

You can parallel multiple power sources on a bus. When you're plugged into shore power or your vehicle alternator, the EPEver won't be doing much, but it won't hurt anything. Just bear in mind the EPEver won't be able to tell you anything about usage (load on the display will show as 0). I like to use a "battery monitor" with a shunt to view actual battery usage in this mode.
 

pbennison

Member
I had that exact unit in my last camper and it worked well for me. So a data point of 1. :)

The charge controller's function depends on how you wire it. The EPEver has three connections: solar input, battery output, and load. If you put ALL your loads on Load then it's "in control" of the entire system. This lets it monitor battery usage, but IMO this is much more difficult to wire properly into an existing RV because we have all those extra things like AUX inputs from the tow vehicle, 120V->DC charge controllers in our power centers, etc. You have to do a lot of rewiring for that to work. Totally my opinion but I don't think it's worth it for the "upgrade an existing RV system" path.

I personally didn't wire anything to Load at all. Solar goes to the solar input, and the battery output goes right to your main 12V bus. I have a fuse on the solar panel wires as near to the panels themselves as possible (I use an inline MC4 style fuse holder), and a battery switch just before it gets to the EPEver. You don't really need to "turn off" the EPEver in general use, it's just very helpful to be able to do when working on your electrical system. You always want to be able to completely turn off all power in your RV, and if you just hook the solar straight in you can't do that - you'll be hot any time the sun is shining.

Fuses protect wires not devices. There's a great chart here:

For 6AWG with a moderately short run looks like you'd want a 40A max fuse. But since the EPEver you bought is 30A I'd probably go with that to be safe.

You can parallel multiple power sources on a bus. When you're plugged into shore power or your vehicle alternator, the EPEver won't be doing much, but it won't hurt anything. Just bear in mind the EPEver won't be able to tell you anything about usage (load on the display will show as 0). I like to use a "battery monitor" with a shunt to view actual battery usage in this mode.
Thank you for the information, this is so helpful. I agree and will not rewire, my main goal for this is to keep the batteries charged while not hooked up to power. I will order the inline MC4 fuse, battery switch, 30A fuse and battery monitor.

Of course I have a couple questions.

I can't seem to find a 30A inline fuse for 6AWG wire. I must be missing something here.
For the battery monitor with shunt. Can you recommend one? I see they range from $5 to $100 on Amazon.

Again, thank you very much it is appreciated.
 

taskswap

Member
For a fuse on the solar wire (which protects against fires caused by stuff like coming into contact with a power line) I use an inline MC4 connector fuse holder:


For a fuse on the internal wiring, such as from the charge controller out to the rest of the system, I use an ANL fuse holder:


These are Renogy links but anything similar will work. For this latter style you want ring terminals on your cables.

For the BMS I've tried several products. So far I haven't found one I love. You'd do best to watch review videos on Youtube because they're all a little different and the best one may be the ones that suits you. My last one was the Renogy 500A and while it worked great I never got much use out of it because the cable was too short for my run to where I want to put it, and there wasn't a replacement or extension available. Some people swear by the Victron but I never loved the round style of it. Totally subjective.

These units are super simple, they all just have a very beefy micro-ohm range "shunt" that you put on the negative (check the docs but it's almost always the NEGATIVE) terminal of your battery. Then they have a screen, Wifi, or bluetooth module with various functions. You can compare the functions on the app or display each one comes with and choose which one you like, they're all doing the same thing. However I would stick with a name brand like Victron, Renogy, or Spartan. Something like that. Youtube reviews are your friends here.

I'm about to do a new solar install and I'm going to try out the Renogy BT-2 combined with their Smart LiFePO4 batteries. That setup doesn't need an additional monitor, you just view status on your cell phone. After having done a few solar installs I've realized that as much as I like a hard-wired display for reliability, I have to admit after the initial "new toy" period I don't really look at it much. If you have to micro-manage it, the system is undersized. And once you have enough capacity you never do. Or at least I never did. So I think I'll mostly be using it to see how the system is performing at first.

My main goals are to be able to run the furnace all night in winter without killing the batteries or needing to run the generator all night, and to be able to run the fridge 24x7 during the summer when we put the camper in storage between trips, so we don't have to empty the fridge every time we park it. Once I'm confident I have enough capacity for those things plus some margin I'll probably ignore it for the most part after that! :)
 

pbennison

Member
For a fuse on the solar wire (which protects against fires caused by stuff like coming into contact with a power line) I use an inline MC4 connector fuse holder:


For a fuse on the internal wiring, such as from the charge controller out to the rest of the system, I use an ANL fuse holder:


These are Renogy links but anything similar will work. For this latter style you want ring terminals on your cables.

For the BMS I've tried several products. So far I haven't found one I love. You'd do best to watch review videos on Youtube because they're all a little different and the best one may be the ones that suits you. My last one was the Renogy 500A and while it worked great I never got much use out of it because the cable was too short for my run to where I want to put it, and there wasn't a replacement or extension available. Some people swear by the Victron but I never loved the round style of it. Totally subjective.

These units are super simple, they all just have a very beefy micro-ohm range "shunt" that you put on the negative (check the docs but it's almost always the NEGATIVE) terminal of your battery. Then they have a screen, Wifi, or bluetooth module with various functions. You can compare the functions on the app or display each one comes with and choose which one you like, they're all doing the same thing. However I would stick with a name brand like Victron, Renogy, or Spartan. Something like that. Youtube reviews are your friends here.

I'm about to do a new solar install and I'm going to try out the Renogy BT-2 combined with their Smart LiFePO4 batteries. That setup doesn't need an additional monitor, you just view status on your cell phone. After having done a few solar installs I've realized that as much as I like a hard-wired display for reliability, I have to admit after the initial "new toy" period I don't really look at it much. If you have to micro-manage it, the system is undersized. And once you have enough capacity you never do. Or at least I never did. So I think I'll mostly be using it to see how the system is performing at first.

My main goals are to be able to run the furnace all night in winter without killing the batteries or needing to run the generator all night, and to be able to run the fridge 24x7 during the summer when we put the camper in storage between trips, so we don't have to empty the fridge every time we park it. Once I'm confident I have enough capacity for those things plus some margin I'll probably ignore it for the most part after that! :)
Thanks again. I have everything ordered and will be connecting it all together this weekend. Agree about the fridge thing, I have emptied and put back 10 times in the past month, getting kind of sick of that.
 

pbennison

Member
Ok, I have everything ready to go and will be heading up today to wire everything in. I have everything figured out but am a little confused about how to wire in the BMS. I want to double check on my assumptions.

From the picture below (BMS), going from top to bottom I have 1-4 with Shunt being 1-2. I use 6AWG from the shunt to the Negative side of Load (Battery), the Negative side from PV and Positive PV to Positive Load (Battery). I can the use 10/12/14 AWG? for the connections 1-4 on the BMS to the shunt and Positive and Negative PV?
 

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