RV Roof Panels

[Lt.Dan]

Hey guys, I’m doing the math to try and line my roof with just as much solar panels as possible while also being as cheap as possible. Basically the most cost effective.

I liked the idea of used panels from SanTan solar or the like, but ALL their panels are too wide to fit between my AC and the edge of the roof, which made it very difficult to find a cheap panel to fit. After emailing SanTan solar, is asked them if they had anything under 32”, which they surprisingly did! They said they are Sunpower 210w Panels that measure 62”x32”, so I got up on my roof today with some painters tape and a tape measure to see how many I could fit. The trailer is 45’ long overall, but with 3 ACs and the vents etc make it a little tough to lay them out and still be able to walk around.



The answer is 12! I was hoping for 14 or so, but I’ll take what I can get, should end up with around 2520 watts, with the 80% rule around 2000 watts?

Trying to figure out how to get more on there...

Has anyone glued a flexible panel to the top of the slides? I have 3 slides that are just wasting space...

Suggestions/ideas?

 

[HRTKD]

Using a CAD program is a lot easier than getting up on the roof of the RV. Don't forget to account for the width of the mounting bracket when you do your layout.

I would not put anything on the top of the slide. The flexible panels are thin, but not that thin. It could cause problems with the slide gasket.

I had to change my plans for solar panels once I did the layout. The original plan was four 200 watt panels. Due to objects on the roof that didn't work. I ended up with two 320 watt panels instead.

 

[texskeet]

You are doing it right. The flex panels are no good your watts are great for an rv I would go with.

 

[WA5IDX]

I wish I had that much room on my RV roof top. I was limited to 22" wide so ended up with 6 each 100 watt panels ( trailer is only 25ft long.). I used mounting brackets from AM Solar (they are not inexpensive but allow you to "Angle" the panels if desired and move them out of the way easily for roof top cleaning). I did my layout on a CAD program AFTER carefully measuring the actual roof top. Don't forget to look at where and how you will combined panels and where the feed from roof to Solar Controller will go. It might change your layout slightly once you decide how how to wire up your panels ( wire runs eat up power so I did #6 AWG to the roof.

Looking like a fun projetc.

 

[markver]

Hey guys, I’m doing the math to try and line my roof with just as much solar panels as possible while also being as cheap as possible. Basically the most cost effective.

I liked the idea of used panels from SanTan solar or the like, but ALL their panels are too wide to fit between my AC and the edge of the roof, which made it very difficult to find a cheap panel to fit. After emailing SanTan solar, is asked them if they had anything under 32”, which they surprisingly did! They said they are Sunpower 210w Panels that measure 62”x32”, so I got up on my roof today with some painters tape and a tape measure to see how many I could fit. The trailer is 45’ long overall, but with 3 ACs and the vents etc make it a little tough to lay them out and still be able to walk around.

View attachment 34769

The answer is 12! I was hoping for 14 or so, but I’ll take what I can get, should end up with around 2520 watts, with the 80% rule around 2000 watts?

Trying to figure out how to get more on there...

Has anyone glued a flexible panel to the top of the slides? I have 3 slides that are just wasting space...

Suggestions/ideas?

2000w is really good for an RV, but if you needed a bit more power the portable ground-based (foldable) units work well and can be moved out to the optimum sun spots when your campsite is in the shade.

 

[Lt.Dan]

Thanks for heads up on the flex panels guys, I'll scratch that idea. Its funny because I'm actually a CAD guy for a sheet metal/laser shop, and run Solidworks everyday. But I didn't want to spend the time carefully drawing out every little thing on the roof, just to be off an inch somewhere and it not work out. I spent the 10 min up on the roof instead.

I would like to do a ground array, but I have 2 kids (2 and 3 years old), and we live on a family members property, so I wanted to be totally self contained.

In the top right of my picture, we have a pole barn that im thinking about mounting panels to as well, and maybe doing fewer on the trailer itself. I can fit an easy 7.5kw of panels on there... maybe more.

Decisions desicions...

 

[HRTKD]

Verify the integrity of the RV roof. You don't want to find soft spots right in the middle of mounting the panels to the roof. I had to fix a corner of my roof due to a little problem. Details in my How To thread linked below.

How To: Mount Panels to an RV Roof

This details the steps I went through for mounting my Mission Solar 320 watt panels to the roof of my RV trailer. While there are multiple methods to secure a panel to an RV roof, this focuses on using standard Z brackets. Other methods include DIY brackets, Unistrut, adhesive tape and all the...

diysolarforum.com

 

[Lt.Dan]

Well it's a 2020 trailer that is 6 months old and has only been in a very light rain twice, so it better be solid! Lol

 

[HRTKD]

Ah, well you should be ok then. GD is a better quality brand, but they're not perfect. My trailer had 14 years to develop a nice soggy area. Annual roof inspections are an absolute must.

 

[chrisski]

Recommend thinking about how the sun will effect these panels. If you park it so the right side of the picture is facing south, shade will really kill the left side. Depending on how you park, you may see 1000 watts or lower. Because of limited roof and shading, consider ground mounted or portable panels.

I have 600 watts of panels on my roof, and I also have 400 watts of panel on the ground. The 400 watts of panels outperforms the roof mounted panels. The jigsaw puzzle of putting panels on my roof was a little different, and some of them have shade throughout half the day. Also, I move the ground mounted panels throughout the day to maximize production.

With the low angle of the sun in the morning, I tilt my portable panels to the sun and at 9:30 I'm getting 20 amps of production, but from the roof panels, I only get 7 amps. Once the sun is high enough in the air, like at 10:30, I may see 40 amps to 45 amps of production if my batteries still need charged.

It looks like the best way to park the RV is the right side to the south, but as the sun sweeps through the sky, the left side panels will be significantly shaded.

 

[Hedges]

Lose the rooftop AC units (some or all), consider a mini-split? (I hear they are more efficient.)

 

[chrisski]

Lose the rooftop AC units (some or all), consider a mini-split? (I hear they are more efficient.)

I like the idea, but with an RV that size, I'm not really seeing how to get a mini-split installed. I've got one about that size and am having trouble figuring out placement.

A smaller RV You can put the unit in the back, but I think the top part of the minisplit would need to go on the side to get even cooling. I don't think you can just cut a hole in the frame on the side to place it. I am thinking a recessed frame on the side that would fit a top portion of the mini-split would be awesome. At least that's the idea I'm kicking around for building my own RV. If I did build one, I'd also find a way to recess the plumbing vents to keep those from shading.

 

[Lt.Dan]

I will definitely read the post about the inspecting the roof and mounting panels, can never be too safe.

I am currently parked with the front of the trailer facing north, I can't get the trailer turned 90* because of the shear size of it and I'm limited on where I can park.

The pole barn has the roof facing south at about 15* angle, so I think it would be optimum, there is also no trees to block it whatsoever.

I would love to replace the roof top ACs with some more efficient ones. These work great, and even in 110* weather last year, all 3 kept the trailer at a brisk 75*, and I felt they couldve gotten it colder! But each one draws about 1600watts so im not planning on running more than 1, and even that, I might be pushing it if I turn on the TV or anything lol.

My trailer is a toy hauler, with the 15' garage in the back, so even putting a mini split in the back would only cool 1/3 of the trailer. Not to mention how would I mount it and still get my RZR in it??

 

[Hedges]

Panels tilted left and right, extending over and shading the rooftop A/C?
That prevents A/C from casting a shadow on panels. Parked facing north, half the panels get morning sun and half get evening.

If rear of RV is windowless, panels vertical (optional tilt-up) would present a lot more area during winter.

 

[chrisski]

I am currently parked with the front of the trailer facing north, I can't get the trailer turned 90* because of the shear size of it and I'm limited on where I can park.

In that case, North facing with panels on each side, you can plan on half production as half are shaded with a bonus both sets will receive light when the sun is high.

But each one draws about 1600watts so im not planning on running more than 1, and even that, I might be pushing it if I turn on the TV or anything lol.

There's a bit more to AC with the start up surge and other things that make AC challenging on solar. In AZ, we have AC on 24 hours a day, and if 110 is typical where you're at, could be the same for you. Mini-splits are supposed to use a lot less energy overall and not have the surge. That's why I'm headed the mini-split direction.

Before you get too far into it, you may need to do an energy audit. For me, I started solar when I ended up at a Dry-Camping site when my 50 amp hookup reservation fell through. I bought a 2300 watt generator the same day so we could have some power. I started my solar build after that so I did not need the generator. By the time I designed and built my solar build with 1000 watts of panels and 458 ah of 12 volt batteries and a 2000 watt inverter, I realized AC was out of the question on my panels, microwave is possible but drains batteries quickly.

So, even with my solar build, when I need to still turn the generator on to run the microwave for twenty minutes a day. I could probably run a single AC off the generator, but I may need to install a soft start.

Also, solar ended up costing me more than I will ever save. If your situation is anything like mine, running a power line to the trailer would by far be the cheapest choice.

I like this video on why with a solar build similar to mine is a bad isea to run AC:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjdoI_g8bzuAhVDMn0KHQiNCroQwqsBMAB6BAgEEAM&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DzawAaI-HS9U&usg=AOvVaw3bdAHm2Zgf49AjS49GU4cG

Not that it can't be done, it just becomes expensive.

 

[Lt.Dan]

Yes I'm afraid the AC units will cast a shadow, especially because they seem to be around 14-16" tall! Again, gonna have to take what I can get though. Another reason to put them on the pole barn, but we'll see.

I'm not too concerned with the initial start up, as I have 280AH at 48v batteries coming, and probably in a few months will get another 280ah, and I also plan on ordering a Growatt SPF 6000T DVM from Ian, which is a 6kw inverter, with 18kw peak. With that much power, I should be able to run all 3, if my batteries/solar can supply it.

I have done an energy audit, all the way to pulling every fuse and measuring current usage, and at most, with everything except the fridge (on 12v/propane) turned off, (lights, TV, etc) I used 100 watts. So i'm pretty happy with the stand by consumption of that, and then the 6000T inverter I'm anticipating drawing another 70w or so. Typical lights we use draw around 50 watts, our TV draws about 100 watts, and then we have our occasional Air Fryer, or Nuwave cook top, which will vary wildly based on what we decide to eat for the day.

Basically I figure 2kw of electricity is going to be more than enough for us.

 

[Lt.Dan]

Hmm. I really like the idea of screwing down 10' lengths of unistrut along the length of the roof, and making brackets that bolt to the unistrut. I feel it will be much more sturdy and easier to be sure i hit the studs under the roof.

I can run 4x lengths of unistrut, basically 2 along the very outside, and 2 equidistant between those. Then I can mount 3 rows of panels all the way down. I won't be able to fit more panels, but they would fit a little easier I feel.

 

[HRTKD]

Would the brackets coming off the unistrut be able to connect to the long sides of the panels? I believe that the panels need to be supported along the long sides. Putting brackets on just the short sides isn't enough support. Your panel manufacturer would have better information on that.

While I didn't look into mounting using unistrut too much, most of the implementations I saw had the unistrut running perpendicular to the panel. That would be something to verify.

 

[Rocketman]

If you want something that costs more than unistrut, but is lighter - look at the 8020 aluminum. If I ever do another Solar on a RV I will look closely at laying down some 8020 1" rails, Then build on that.

 

[Lt.Dan]

Would the brackets coming off the unistrut be able to connect to the long sides of the panels? I believe that the panels need to be supported along the long sides. Putting brackets on just the short sides isn't enough support. Your panel manufacturer would have better information on that.

While I didn't look into mounting using unistrut too much, most of the implementations I saw had the unistrut running perpendicular to the panel. That would be something to verify.

Yes, the unistrut would run lengthwise with the panel, so I can bolt to the long side. Also, because of the nature of unistrut, I have infinite adjustability where the bracket bolts to the panel itself, meaning i can put as many mounts as I want!