Help w/RV Curved roof mount, weight limits, flexible panels

[Enigma86]

Hello, I am looking for help on figuring out the best selection here to go for getting the solar panels to finish out my solar system on my 34 ft 5th wheel RV. I've got a couple of issues that I'm running into as I look for solutions. For starters, I have 3 100 AH lithium 48v batteries in the front storage along with a SP6548 from SunGoldPower that I'll be running all panels to. Till now I've just been charging batteries with my generator or shore power. I'm full time and work from my RV.

Pictures are attached of roof for reference.

Needs, my electrical goal is to cover my running wattage on a day where I'm running the rear A/C while also running my laptop and monitors and things of that nature. I'm trying to cover this load with a little wiggle room to spare. Last summer I was able to consistently measure this as about 2000 watts. So I would like to get 2400 real watts in.

One big issue I'm running into is weight. My initial plan was to get 6 550w panels and mount horizontal front to back over my front AC unit, this would run me about 400 lbs. After I got the chance to weigh my rig, however, I came in FAR above what I thought I would weigh. I could not believe I had already used up my 3000 cargo capacity. I am making changes to furniture and dumping as much as I can but that can only go so far. I have considered trying to either do an ALL flexible panel setup somehow, or to do some kind of hybrid and still get a couple 550w panels up there and then also do some flexible ones.

After some research though I'm seeing that the flexible panels might just bake the roof of the RV and end up pumping even more heat into the RV and/or could even cause burning issues? And I honestly never figured out even doing the rigid panels what the best way to do the mounting if not doing a rack over the A/C units as my roof has a significant curve. So any insight into exactly how that is supposed to happen would be helpful. I've heard unistrut and stuff but I don't see how any thing you mount on that surface won't be angled off in the direction of the roof.

Would there be any way to do slightly raised rack system and still use flexible panels? Even though I know that it sounds kinda silly because it takes away a lot of what they are good for, they are so light compared to the rigid ones.

All of these issues are difficult to sort out since I kinda need to figure out the game plan before just buying a bunch of panels.

Just for note when looking at the RV roof pictures, without racking over the A/C the places a 550w panel can fit is horizontal in front of the front A/C, and then two can be vertical behind the max fan, in front of the rear A/C.

Questions recap:
If I put 550w panels on, what would be the most elegant and sturdy mounting solution both for a horizontal mount and then for vertical?
Should I be worried about the increased heat of flexible panels?
If I should be worried about the increased heat, is there a viable racking solution that could be done to get the weight savings of flexible panels?

I understand this is kinda complicated so I appreciate anybody willing to add some insight.

 

[justinm001]

If weight is an issue I'd go with much smaller panels as they're lighter. Since smaller they use less glass and can just be thinner with frames. The renogy 100w I have are super light.

I'd suggest mounting them vertically and tilt them to cover the roof, depending on how much height you have. I did this and much happier than flat mounted

 

[chrisski]

If weight is an issue I'd go with much smaller panels as they're lighter.

I’d check specs to be sure.

My 400 watt roof panel weighs 45 lbs, but my 100 watt Rv panels weigh 15 lbs or 60 lbs for 400 watts.

I have considered trying to either do an ALL flexible panel setup somehow, or to do some kind of hybrid and still get a couple 550w panels up there and then also do some flexible ones.

I have a hybrid of flexible and flat panels on my roof. Details are in my signature block.

If you go the flexible route, be prepared to swap some out as they go bad. I’m on season 3 with flexible panels and 0 issues. Others have lost them after a year or sooner.

They are more pricey, but 4” roofing tape all around which also is pricey has held my panels down.

I’ve also had good luck with portable panels, but I’m out in the winter when those are better. When I run AC in the summer or run the fridge in the winter, these need to come out.

 

[justinm001]

I’d check specs to be sure.

My 400 watt roof panel weighs 45 lbs, but my 100 watt Rv panels weigh 15 lbs or 60 lbs for 400 watts.

I have a hybrid of flexible and flat panels on my roof. Details are in my signature block.

If you go the flexible route, be prepared to swap some out as they go bad. I’m on season 3 with flexible panels and 0 issues. Others have lost them after a year or sooner.

They are more pricey, but 4” roofing tape all around which also is pricey has held my panels down.

I’ve also had good luck with portable panels, but I’m out in the winter when those are better. When I run AC in the summer or run the fridge in the winter, these need to come out.

Interesting, I guess you're right, they just feel so much heavier so I assumed. But 14 vs 40 lbs for 100 v 320 renogy panels I have

 

[Enigma86]

I’d check specs to be sure.

Yeah, I've done the analysis on this and both watt per pound and watt per square inch is almost always better on larger panels than smaller which is why I'm trying to opt for larger panel any chance I can.

I’ve also had good luck with portable panels, but I’m out in the winter when those are better. When I run AC in the summer or run the fridge in the winter, these need to come out.

I'm not sure I understood this comment. These need to come out? Have you had any issues noticing that your RV heats up a lot faster with the flexible ones mounted?

Thank you for the reply!

 

[chrisski]

I'm not sure I understood this comment. These need to come out?

Flexible panels have a bad rep for dying quick.

Have you had any issues noticing that your RV heats up a lot faster with the flexible ones mounted?

Doesn’t heat up any quicker, at least that I can notice.

On a 195 f day, The flexible panels measure at 155 f and the flat panels measure at 130 f.

Of it’s that hot out, a single 15k btu unit won’t keep up and I don’t take the Rv out.

A single 15 k BTU works fine when daytime temps reach 90, after that I need to turn both on. The RV build part 2 in my signature block says what it takes to run an AC.

For mounting flexible panels I don’t recommend Rv with Tito’s mounting with plastic cardboard. I did that and there was not enough surface area to hold the panel down on my rubber roof and where it was secured bubbled. I notice you also have a rubber roof.

 

[Enigma86]

Doesn’t heat up any quicker, at least that I can notice.

On a 195 f day, The flexible panels measure at 155 f and the flat panels measure at 130 f.

Ok thank you for the answer on that one.

On a 195 f day, The flexible panels measure at 155 f and the flat panels measure at 130 f.

I'm really hoping you mean 95. Otherwise those numbers are stellar!

Of it’s that hot out, a single 15k btu unit won’t keep up and I don’t take the Rv out.

A single 15 k BTU works fine when daytime temps reach 90, after that I need to turn both on. The RV build part 2 in my signature block says what it takes to run an AC.

For mounting flexible panels I don’t recommend Rv with Tito’s mounting with plastic cardboard. I did that and there was not enough surface area to hold the panel down on my rubber roof and where it was secured bubbled. I notice you also have a rubber roof.

Correct, I have the same experience. I plan to be north for the summers so I'm hoping to stay out of 90+ very often at all. I will also have a generator for if I'm in dire need of the second A/C. I've already become very familiar with the running wattage of my units. And noted about the cardboard mounting. Information like that is really helpful, otherwise I might end up down a rabbit hole like that.

 

[wme]

Here is one persons answer, this is his current version, each revamp gets better. Several hours of Utube watching to follow his adventure.

 

[chrisski]

Here is one persons answer, this is his current version, each revamp gets better. Several hours of Utube watching to follow his adventure.

It does look better than his earlier method, but I would still tape completely around the panel

With this new method, seems like a lot of work and barring the OPs weighr requirements, seems just as easy to put A flat panel on the roof. On Tito’s new trailer, he did a screw less flat panel installation with Sika Flex.

 

[0truck0]

So, are you wanting to run your air cond on the solar?

If not, then you do not need 2400 watts of solar. 2400 is a LOT of solar. Everything, everyone I have seen almost concludes is best to run gas generator for air cond, and everything else can run on battery if you are not needing air cond. There are rigs that successfully do air cond on solar/battery, but this is full timers with big roof acreage and bigger battery banks and since they full time then is worth the big expense. Decide if it is worth it, and you do not have the roof space for such an array either.
Are you really going to be using 2400 watts all the time, or 2,000??? Even the air cond will cycle so will not use its full watt needs all the time. Again, this is a pretty big use of power, maybe look at RV forums for tips to help conserve power.

You can use flex panels. I dont recommend then for their many faults, but they do work perfectly until they break.
I would not put them on a raised rack.
You have to get air under them. Yes, will "burn" the roof if they sit on it. I suggest using corrugated plastic sheets under them. The flutes in the plastic will give you air under the panels and insulate the roof from the panel as well. You wll have to tape these on with VHB tape, but do not block both ends of the plastic flute channels. You do not need a continuous tape job, just tape segments, this way you can leave the other side flute open to the air. If you can come up with your own method to have such an air gap then go for it. I have done this one successfully.

Beware of taping the panel down and water cannot drain out. Looks like you have aluminum roof, and if water gets trapped under will rot out your roof.

IF using glass panels then I doubt the weight is an issue. You are spreading the weight out, so think of pounds per square inch instead of total weight. The weight you talking about over such a large roof will not be an issue. Be sure the brackets land on a roof frame member, not between them.

As far as your GVW issue, that is all on you, cant help u there.

 

[eXodus]

Newpowa Solar Panel Mounting Curved Z Bracket with Nuts and Bolts Supporting for RV https://a.co/d/4w2E70J

I got those things under my 460w panels on my RV for the last 2 years.

6 per panel.

On the outside corners the curved mount, and in the middle regular flat mounts.

https://www.amazon.com/dp/B00WL1VB68?ref=ppx_pop_mob_ap_share

 

[justinm001]

So, are you wanting to run your air cond on the solar?

If not, then you do not need 2400 watts of solar. 2400 is a LOT of solar. Everything, everyone I have seen almost concludes is best to run gas generator for air cond, and everything else can run on battery if you are not needing air cond. There are rigs that successfully do air cond on solar/battery, but this is full timers with big roof acreage and bigger battery banks and since they full time then is worth the big expense. Decide if it is worth it, and you do not have the roof space for such an array either.
Are you really going to be using 2400 watts all the time, or 2,000??? Even the air cond will cycle so will not use its full watt needs all the time. Again, this is a pretty big use of power, maybe look at RV forums for tips to help conserve power.

You can use flex panels. I dont recommend then for their many faults, but they do work perfectly until they break.
I would not put them on a raised rack.
You have to get air under them. Yes, will "burn" the roof if they sit on it. I suggest using corrugated plastic sheets under them. The flutes in the plastic will give you air under the panels and insulate the roof from the panel as well. You wll have to tape these on with VHB tape, but do not block both ends of the plastic flute channels. You do not need a continuous tape job, just tape segments, this way you can leave the other side flute open to the air. If you can come up with your own method to have such an air gap then go for it. I have done this one successfully.

Beware of taping the panel down and water cannot drain out. Looks like you have aluminum roof, and if water gets trapped under will rot out your roof.

IF using glass panels then I doubt the weight is an issue. You are spreading the weight out, so think of pounds per square inch instead of total weight. The weight you talking about over such a large roof will not be an issue. Be sure the brackets land on a roof frame member, not between them.

As far as your GVW issue, that is all on you, cant help u there.

Not sure I agree. 2400w flat mounted in the winter yields what 5kw per day if lucky? 10kw on a perfect sunny summer day?

A decent size fridge will burn 1kw so will an inverter being on. So op is left with 3-7kw to actually use.

 

[chrisski]

2400w flat mounted in the winter yields what 5kw per day if lucky?

I agree with this. I doubt the OP will fit that much. My RV is the same as his and in theory it could fit, but vents, ACs and skylights would need to be covered.

You wll have to tape these on with VHB tape, but do not block both ends of the plastic flute channels.

Do you do this?

I’d like to see pics and see how many miles. Mine lasted less then a year.

As I stated earlier this did not work for me. Air got under the panel and vibrated it.

If not, then you do not need 2400 watts of solar. 2400 is a LOT of solar. Everything, everyone I have seen almost concludes is best to run gas generator for air cond, and everything else can run on battery if you are not needing air cond.

As running a 1700 watt 15k BTU from AC, I also disagree with this. 2400 watts may not be enough if these panels are flat. IME I have 1200 watts ground mount and 1350 watts roof mount and that struggles to keep up and charge the battery.

I do agree a more rationale decision would be to run on a generator.

 

[0truck0]

All depends on what you are running off the batteries.... I cant guess.

If trying to have an inverter on all the time and runing a residential large fridge, and a hair dryer, and an AC coffee pot and AC cook top, and other house items then you will need a lot of power. If you have smaller chest DC fridge that is way more efficient and only use inverter for those minutes and have propane cook top etc and do not try to use a lot of power then it is correct that 2400 is over-kill, but just depends on what you trying to run , which Im still in the dark about... good luck.

And, yes, I taped the panels on, you have to tape the entire leading edge and trailing edge or air could blow under it on the highway of course. Then tape sections down the side too. I actually cut some strips of the same plastic and put those under a full sheet of plastic so the air gap was just the thickness of the corrugated plastic. Is meant to allow air under it, nothing else, so with such a small gap air will not get under it enough at highway speeds to o anything. Again, do not have a gap pointing into direct highway air flow - if far enough back on the roof from the leading edge then you will not have issues unless you are on a very aerodynamic sports car roof where the air flow is laminar. Air flow on a camper roof is far far from laminar.

If you dont understand the logic I suggest to not try this method.

 

[chrisski]

All depends on what you are running off the batteries.... I cant guess.

If trying to have an inverter on all the time and runing a residential large fridge, and a hair dryer, and an AC coffee pot and AC cook top, and other house items then you will need a lot of power. If you have smaller chest DC fridge that is way more efficient and only use inverter for those minutes and have propane cook top etc and do not try to use a lot of power then it is correct that 2400 is over-kill, but just depends on what you trying to run , which Im still in the dark about... good luck.

And, yes, I taped the panels on, you have to tape the entire leading edge and trailing edge or air could blow under it on the highway of course. Then tape sections down the side too. I actually cut some strips of the same plastic and put those under a full sheet of plastic so the air gap was just the thickness of the corrugated plastic. Is meant to allow air under it, nothing else, so with such a small gap air will not get under it enough at highway speeds to o anything. Again, do not have a gap pointing into direct highway air flow - if far enough back on the roof from the leading edge then you will not have issues unless you are on a very aerodynamic sports car roof where the air flow is laminar. Air flow on a camper roof is far far from laminar.

If you dont understand the logic I suggest to not try this method.

I’d like to see pics of your setup.

I did this off RV with Tito’s video.

The bubbling in the pic is why I don’t recommend this removable set up with corrugated cardboard on a rubber roof. The tape started to pull the rubber roof off the wood under it.

I have the leading and trailing edges taped completely taped, with one more piece of tape in the middle to rack the middle down. The corrugated plastic openings are not into the wind but perpendicular to it.

You can see the bubbling in the middle. It is actually much worst than it seems in the picture. This panel is in the middle of the RV.

 

[0truck0]

I like the removable method. What is the bubbling? Sounds like a personal issue, not the tape as the tape almost always sticks well. Your method is good, but not sure why you have a bubble. The method should not be tossed out just because you have issues that should not happen. Solve the issue.

 

[chrisski]

The method should not be tossed out just because you have issues that should not happen. Solve the issue.

Sigh. I really would like to see recent pics of your setup.

What is the bubbling?

The bubbling is from the wind getting under the panels, vibrating, and pulling the rubber roof and the glue between the rubber roof and the wood that rubber roof.

The bubbling is what is circled in red on the tape.

 

[Sportzfann]

Hello, I am looking for help on figuring out the best selection here to go for getting the solar panels to finish out my solar system on my 34 ft 5th wheel RV. I've got a couple of issues that I'm running into as I look for solutions. For starters, I have 3 100 AH lithium 48v batteries in the front storage along with a SP6548 from SunGoldPower that I'll be running all panels to. Till now I've just been charging batteries with my generator or shore power. I'm full time and work from my RV.

Pictures are attached of roof for reference.

Needs, my electrical goal is to cover my running wattage on a day where I'm running the rear A/C while also running my laptop and monitors and things of that nature. I'm trying to cover this load with a little wiggle room to spare. Last summer I was able to consistently measure this as about 2000 watts. So I would like to get 2400 real watts in.

One big issue I'm running into is weight. My initial plan was to get 6 550w panels and mount horizontal front to back over my front AC unit, this would run me about 400 lbs. After I got the chance to weigh my rig, however, I came in FAR above what I thought I would weigh. I could not believe I had already used up my 3000 cargo capacity. I am making changes to furniture and dumping as much as I can but that can only go so far. I have considered trying to either do an ALL flexible panel setup somehow, or to do some kind of hybrid and still get a couple 550w panels up there and then also do some flexible ones.

After some research though I'm seeing that the flexible panels might just bake the roof of the RV and end up pumping even more heat into the RV and/or could even cause burning issues? And I honestly never figured out even doing the rigid panels what the best way to do the mounting if not doing a rack over the A/C units as my roof has a significant curve. So any insight into exactly how that is supposed to happen would be helpful. I've heard unistrut and stuff but I don't see how any thing you mount on that surface won't be angled off in the direction of the roof.

Would there be any way to do slightly raised rack system and still use flexible panels? Even though I know that it sounds kinda silly because it takes away a lot of what they are good for, they are so light compared to the rigid ones.

All of these issues are difficult to sort out since I kinda need to figure out the game plan before just buying a bunch of panels.

Just for note when looking at the RV roof pictures, without racking over the A/C the places a 550w panel can fit is horizontal in front of the front A/C, and then two can be vertical behind the max fan, in front of the rear A/C. View attachment 188789View attachment 188790

Questions recap:
If I put 550w panels on, what would be the most elegant and sturdy mounting solution both for a horizontal mount and then for vertical?
Should I be worried about the increased heat of flexible panels?
If I should be worried about the increased heat, is there a viable racking solution that could be done to get the weight savings of flexible panels?

I understand this is kinda complicated so I appreciate anybody willing to add some insight.

I just installed some used panels and unistrut on my rv roof it is a raised system with rigid panels 4 of them @325 W 400ah lifpo I used VHB tape and some screws into the roof. Sealed up with dicor over screws. I think the panels are about 42lbs. ea. plus the 50’ of unistrut @9 lbs ea.
have you thought about beefing up your suspension system springs, axles, tires? Sounds like you were concerned about your total weight, a couple hundred pounds won’t make a lot of difference I think. Plus mounting on strut you can remove and change panels or add tilting etc later.
My wife works remote in the fifthwheel and I am wanting to run all my electrical except the AC unit, on my batteries. I just finished a couple days ago and it’s been cloudy, so I don’t have a lot of data yet, but I expect the solar will cover all the daily loads and charge my batteries completely.

 

[0truck0]

Ok, so you r trying to mount things to a rubber film that is stickie to the roof?
I would suggest to mount a frame, like a car roof rack for ladders or bikes, that mounts to the sides (think like the gutters on an suv) and have your custom rack span over the roof to hold panels in place. The other option is to screw through the rubber membrane to something solid, and I can tell you this is not ideal as I hear all the time roof leaks from things going through the membrane. It can be done, but high chance you leak.
Mount you rack mounts to the siding at the roof, not on the roof. It could even sit on the roof, could be a metal strap that crosses the roof and at least that give you a mounting surface to tape to. Not a lot of good options on the rubber roof.

This is more of a question for an RV forum than a solar forum, find people who have made mistakes on rubber roofs already....

 

[Tomthumb62]

Flexible panels get a bad reputation. In my opinion, I would bet the bad reputation comes from improper installation or using them on the wrong surface or conditions.

What I mean is if you install flexible panels on a metal roof, with no air gap and travel to the American Southwest in summer, you’re going to get a short life span.

But if you install them on a cooler roof (ours is wood covered by canvas) and keep out of extreme heat locations in summer (we’ve averaged 80-95F in summer), you’ll get a long life span. An air gap will extend life even more.

That said, the only flexible panels I’ll recommend going forward are the Sunpower ones. Sunpoweredyachts dot com sell them in the USA. They are so much better built than anything else out there for the price. I paid about $160 per 100W panel, but they have other sizes too. I think I heard rumors of a 200W one coming out soon.

That said, our cheaper 100W ones from WindyNation are still thriving 6 years later, but when they die, I’ll replace with Sunpower ones.

Edit to say: rigid panels will almost certainly outlive flexible ones every time. But in cases like yours, the weight factor might make flexible panels to be your best option. Buy high quality ones, install and treat them well and they’ll last you many years.