Mobile solar mounting a an odd roof shape

[midwestsolarnoob]

Hi guys! Always a pleasure to ask questions on here, everyone is super helpful!

Here’s my concern. I’ve been going back and forth on how the hell to mount panels on our roof. Back story, it’s an 2008 E350 Cutaway van outfitted by TurtleTop shuttle company. Just under 23 ft bumper to bumper. Roof width is about 70” and the length before the front dips down is around 14ft.

To get the best bang for our buck we are leaning towards Renogy 450W panels 75.2”L x 44.6”W. This should provide plenty of charge for 1200Ah or more of EG4 lithium server batteries(leaning towards these due to many of Will’s review videos).

Now what would be the best way to mount the most Watts on the roof? We will just have a Maxx Fan up top as we’re going the mini split route for A/C.

I’ve been thinking of building an aluminum roof rack from square tubing. But I’m not sure what other ideas are out there! Thanks for any help!

 

[justinm001]

Doesn't seem very tall, I'd suggest angling them a bit so there's a pitch to cover the sides a bit. Also gives room for the fan on the roof to be under it.

For the front I'd put a panel angled

 

[HarryN]

I have installed solar panels onto a fiberglass / plastic roof like that and it takes very careful consideration.

There is nearly no strength in those types of roofs.

The load needs to be spread out on the inside using fender washes and ideally additional sheet metal to prevent stress cracking.

What I do is make cut outs of a few solar panels sizes and play with them on a roof like that to see what is viable.

Don't get hung up on using a single panel solution to save a few $s. Having more bolt down points to work with and possibly a much easier time getting them up there without damaging the roof is worth a lot more than the minor savings on panels.

 

[Supervstech]

If it were me, I would install full length aluminum superstrut
Get the size strut that rises above the side edges if you need full width, or use thin strut if you want to set the panels flush with the top of the edge rung.

 

[Rocketman]

With the panel you selected- I assume you are going to put the panel sideways so the length of the panel 75” overhangs the roof 70” by a couple of inches each side. That will give you 3.81 panels - so three panels- will those three fit with where the fan is located?
Next question… do the Elec specs let you wire them in parallel to the EG4? Or will they have to be in series?

If you want even more watts on the roof - you could run a second set of wires to the roof - fill in the space with 100w panels - then get a mppt and connect the 100w panels straight to your batteries. It may work or may not…

Play around with some other panels- a smaller size (with more panels might enable more solar…

Good Luck

 

[0truck0]

Agree ^, I would use multiple smaller panels so you fit the shape better, or build the super structure frame. If it were me I would use aluminum angle iron, the thin 1.5 inch (or so) from HD, and tape it on with double sided VHB tale, tape the angle iron on the roof front to back oriented, and attach the panels to that using self tapping bolts. I have done this method on 4 campers. Though, yo might need to pre-bend the angles so the panel and the aluminum angle mate up flat before bolting together.
Forget the roof vent for now, solar should take priority and the roof went will just shade your panels anyway. Put vents somewhere else, that is a big regret for me putting a vent that conflicts with the solar panels. There are smaller, less tall, vents so consider one that fits under the panel if you need roof vents, not the big 14x14 style that opens up so tall. Get creative.
DO NOT even consider the flexible panels, so many issues on these.

 

[midwestsolarnoob]

Doesn't seem very tall, I'd suggest angling them a bit so there's a pitch to cover the sides a bit. Also gives room for the fan on the roof to be under it.

For the front I'd put a panel angled

I’ve read numerous places the angling of panels also helps with keep them clean. But thanks for the reply!

 

[midwestsolarnoob]

I have installed solar panels onto a fiberglass / plastic roof like that and it takes very careful consideration.

There is nearly no strength in those types of roofs.

The load needs to be spread out on the inside using fender washes and ideally additional sheet metal to prevent stress cracking.

What I do is make cut outs of a few solar panels sizes and play with them on a roof like that to see what is viable.

Don't get hung up on using a single panel solution to save a few $s. Having more bolt down points to work with and possibly a much easier time getting them up there without damaging the roof is worth a lot more than the minor savings on panels.

Thanks for the info! I’ve thought about something similar as far as using sheet metal for support. The fiberglass roof is sadly very thin. We’re also not set on a panel choice yet. It’s essentially down to a balance between the most watts and cost. We want to have an overall build that can potentially serve as a full time residence for multiple years but be affordable enough for our budget.

 

[midwestsolarnoob]

If it were me, I would install full length aluminum superstrut
Get the size strut that rises above the side edges if you need full width, or use thin strut if you want to set the panels flush with the top of the edge rung.

You’re suggesting using the strut for a base running along both edges of the roof?

 

[midwestsolarnoob]

With the panel you selected- I assume you are going to put the panel sideways so the length of the panel 75” overhangs the roof 70” by a couple of inches each side. That will give you 3.81 panels - so three panels- will those three fit with where the fan is located?
Next question… do the Elec specs let you wire them in parallel to the EG4? Or will they have to be in series?

If you want even more watts on the roof - you could run a second set of wires to the roof - fill in the space with 100w panels - then get a mppt and connect the 100w panels straight to your batteries. It may work or may not…

Play around with some other panels- a smaller size (with more panels might enable more solar…

Good Luck

Sideways yes, that seems to be the best way to fit those specific panels. They’re the panels we’d like to use if we build an elevated roof rack. Which if we go with a flush mounting system we will probably use smaller panels and get more creative lol. We’re getting a Victron MPPT. I left that out of the original post. So panels-> charge controller-> lithium bank. Hardware wise I think we have down it’s essentially just how to mount the panels most efficiently for the most watts.

 

[midwestsolarnoob]

Agree ^, I would use multiple smaller panels so you fit the shape better, or build the super structure frame. If it were me I would use aluminum angle iron, the thin 1.5 inch (or so) from HD, and tape it on with double sided VHB tale, tape the angle iron on the roof front to back oriented, and attach the panels to that using self tapping bolts. I have done this method on 4 campers. Though, yo might need to pre-bend the angles so the panel and the aluminum angle mate up flat before bolting together.
Forget the roof vent for now, solar should take priority and the roof went will just shade your panels anyway. Put vents somewhere else, that is a big regret for me putting a vent that conflicts with the solar panels. There are smaller, less tall, vents so consider one that fits under the panel if you need roof vents, not the big 14x14 style that opens up so tall. Get creative.
DO NOT even consider the flexible panels, so many issues on these.

I’ve read so many horror stories on flexible panels! I wish the technology was better it would save so much time and energy. But sadly it’s not.

I do like your idea for a mounting base. I honestly never thought of it before. I could easily make some custom brackets to attach panels. Would it be smart to use two charge controllers with two sets of different sized panels to fill in the extra space? Our whole goal is to be as independent of the grid as possible.

Also using the tape and angle iron would save our roofs integrity. Sadly very thin fiberglass.

 

[HarryN]

Well the nice thing about a composite roof is that at least it will not be as hot to the touch compared to a steel sheet.

Also if it is in fact fiberglass, there are marine and auto places that specialize in that kind of work. Perhaps they can help you with ideas for re-enforcement.

 

[Supervstech]

You’re suggesting using the strut for a base running along both edges of the roof?

Yes.
I would VHB tape the entire length of the strut, then add through bolts and washers through the roof.
Then it’s a simple matter to add cone nuts, and lock down the panels.

 

[midwestsolarnoob]

I would VHB tape the entire length of the strut, then add through bolts and washers through the roof.
Then it’s a simple matter to add cone nuts, and lock down the panels.

I’m not sure yet if I want to risk that many holes in the roof. What’s the problem with just using vhb tape? I’ve seen a lot of people using it alone without screws or bolts

 

[Supervstech]

I’m not sure yet if I want to risk that many holes in the roof. What’s the problem with just using vhb tape? I’ve seen a lot of people using it alone without screws or bolts

It is a D.O.T. violation, and zero installation instructions support it...
I have seen a lot do this as well...
That doesn't make it right.

 

[midwestsolarnoob]

It is a D.O.T. violation, and zero installation instructions support it...
I have seen a lot do this as well...
That doesn't make it right.

I’m not sure where you found the D.O.T. requirements for mounting solar panels? My experience DOT regulations apply to commercial vehicles.

Understandably I want the panels to be as sturdy as possible. But having only 2-300lbs of panels with wait distributed properly, I’m still not seeing the added precaution of both vhb and some sort of bolts or screws. From what I’ve read and what 3m advertises. Plus they sell high temp tape good to 300 F which eliminates the heat arguments.

Not arguing either. I have read just as many people suggest your way as suggesting just tape.

 

[justinm001]

I’m not sure where you found the D.O.T. requirements for mounting solar panels? My experience DOT regulations apply to commercial vehicles.

Understandably I want the panels to be as sturdy as possible. But having only 2-300lbs of panels with wait distributed properly, I’m still not seeing the added precaution of both vhb and some sort of bolts or screws. From what I’ve read and what 3m advertises. Plus they sell high temp tape good to 300 F which eliminates the heat arguments.

Not arguing either. I have read just as many people suggest your way as suggesting just tape.

I don't see how it's a DOT violation. So many parts on cars are mounted with VHB tape spoilers, trailer side panels, even my Prevost stainless steel siding is all VHB tape mounted.

Although I wouldn't trust VHB tape for solar panels and would much rather screw them down and use VHB to help secure and give a bit of a cushion so they don't bounce.

 

[midwestsolarnoob]

I don't see how it's a DOT violation. So many parts on cars are mounted with VHB tape spoilers, trailer side panels, even my Prevost stainless steel siding is all VHB tape mounted.

Although I wouldn't trust VHB tape for solar panels and would much rather screw them down and use VHB to help secure and give a bit of a cushion so they don't bounce.

Exactly why I was curious as to how dot has anything to do with it. I’m an automotive technician and many vehicle related parts are mounted that way.

I don’t think I would directly mount panels with just vhb tape either. But wouldn’t 14+ ft of aluminum angle iron mounted with vhb tape, properly prepped of course, would properly distribute the weight of panels? Or rather 4 sections long ways on a fiberglass roof (roughly 14 ft each). Using 1.5” high temp vhb tape. With possibly 4-6 mounting points per panel, bolted to the angle iron bases. Maximum weight being roughly 300 pounds of panels.

Again just me theorizing mounting systems. Not suggesting I know the best way or the most stable.

 

[justinm001]

Yes i'm sure it'll work and be perfectly fine. Its not so much the weight of the panels but the risk of air getting under it and pulling the panels off. But on a van/truck/bus with a high roof that air is going way above/around the roof and there isn't really any air able to get under the panels. My panels are angled with massive gaps and no issues at all with wind. Actually if you look real close in that photo there's a 6ft section of angle between AC 1 and 2 that I forgot about and was up there for a month+ and couple thousand miles.

I've been trying to figure out how to mount the brackets for the other half of the panels. On the mounted side it has those same Girard awnings but there isn't any awnings so I easily drilled through it. I don't want to risk a bolt inside the casing ripping my awnings so was thinking about welding unistut but maybe VHB mounting the unistrut is a good idea with a couple pieces of angle on the girard brackets screwed in for backup.

 

[Hedges]

... then add through bolts and washers through the roof.

Strip of 3/8" or 1/2" plywood full length inside, to back up the washers?

It is a D.O.T. violation, and zero installation instructions support it...
I have seen a lot do this as well...
That doesn't make it right.

For the relatively flat portion of the roof, if I could use an unframed laminate (or remove frame), make a cut-out for junction box(s), put VHV all the way around perimeter and pieces in the middle so panel is curved and laminated to roof, then apply 100 MPH tape over the edges ... I might trust that.