Strut channel for roof of RV

K8MEJ

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I've decided to use low-profile (13/16") strut channel for the roof of my travel trailer upon which I will mount tilt brackets and 200 watt Rich solar panels. The tilt brackets might not be used often for tilting the panels toward the sun, but will allow me to raise the panels for maintenance or allow me to tilt them up and out of the way if I want to take the shrouds off the A/C units, fans, etc.

Aluminum strut channel would be nice for weight savings and corrosion resistance. However, it's not easy to find and will likely have to be ordered from an industrial or electrical supplier. And it's more expensive. An alternative is the gold tone galvanized steel strut. It's readily available and less expensive, but will weigh more. I don't live near the ocean, but I'm concerned about using the galvanized strut on the roof of a camper that is not stored inside. I could paint it for an extra level of protection, but I don't know about the longevity.

Should I pony up the cash and order aluminum strut channel or will the higher quality electro-galvanized stuff work well enough for this application?

Thanks!
 

denpmt

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Oct 22, 2020
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I bought low profile slotted aluminum strut to mount two 100 watt solar panels on the roof of my van. It's been up for a couple of Colorado winters and it's holding up well. I don't have tilting brackets but I think it would work well for that purpose.
 

JoeHam

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The big box stores carry aluminum angle but I don’t know if that’s strong enough for your purpose.
 

chrisski

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If the panels are made of aluminum, to avoid galvanic corrosion, aluminum struts would be good. Don’t know how much of a factor this really is, and I imagine it is f=more likely to happen after years.

As far as tilt panels, I don’t think they’re good on an RV roof unless secured really good. More often than not, when I take my RV out, there’s winds that kick up out of nowhere, from 15 knots to 35 knit’s, either shortly before sunrise or shortly after. With the panels up, that is like a sail powering a bolt. I think they could tear out of the roof if the wind blows at the correct angle.

I have mine secured with 2 sided VHB tape and self tapping screws. If I were to tilt mine, I’d want at least fender bolts underneath, or better yet another strip of aluminum on the inside of the roof to make it nice and strong.

Not sure if the winds I saw were unique to a microclimate I was at by the edge of a mountain and plains in a couple different places, or even seasonal, but I got that enough and quick enough to think twice about raising the panels on my roof since it takes about an hour for me to get them up and down. Six panels with four bolts each to raise and lower.

I do have portable / tiltable ground panels I move if the weather is not bad. I have those out right now and early in the morning my flat 950 watts of roof panels were pushing 4 charging amps and my 400 watts of ground panels pushed 16 amps.

I’m not sure what maintenance will be needed on my tilt panels, but done over again, I’d probably go with the cheaper non-tilt mounts.
 

Lt.Dan

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I plan on doing the same thing as you, but on a little bigger scale. I just got a quote for regular galvanized Unistrut from our local material supplier at work (who we spend millions with each year) and he came back at $1.90/ft. I am putting 12x 240watt panels on the roof of my trailer and am going to need quite a bit of unistrut.

I hadn't thought about adding more corrosion resistance though, is the galvanic coating typically not enough? I don't think I've ever seen unistrut rust out, but I also live in Central California where we see about 4 days of rain per year 🙄
 

chrisski

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I hadn't thought about adding more corrosion resistance though, is the galvanic coating typically not enough?
I’d like to know if galvanic corrosion is a thing. I was an avionics technician a long time ago for a few years and remember being taught to look for it and it was a bad thing, but never remembered actually seeing it.

I think in part, that is because of all the effort put into building the equipment to make sure that it was the same metals. So, I never got to see dissimilar metals on the equipment I work on corrode, but we did have an example of a bolt an aluminum bolt and steel washer with galvanic corrosion in the shop. I saw this raised as a concern with dissimilar metal installations on solar with aluminum mounts and stainless steel bolts, but the guy reported back after a year on the roof, no sign of corrosion.
 

Zwy

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I’d like to know if galvanic corrosion is a thing. I was an avionics technician a long time ago for a few years and remember being taught to look for it and it was a bad thing, but never remembered actually seeing it.

I think in part, that is because of all the effort put into building the equipment to make sure that it was the same metals. So, I never got to see dissimilar metals on the equipment I work on corrode, but we did have an example of a bolt an aluminum bolt and steel washer with galvanic corrosion in the shop. I saw this raised as a concern with dissimilar metal installations on solar with aluminum mounts and stainless steel bolts, but the guy reported back after a year on the roof, no sign of corrosion.
Aluminum and stainless are fine, mild steel and aluminum is quite another thing. Add in some moisture with road salt or chloride and it accelerates rapidly.
 

K8MEJ

Owner, Off-Grid Power Systems
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Central Ohio
I plan on doing the same thing as you, but on a little bigger scale. I just got a quote for regular galvanized Unistrut from our local material supplier at work (who we spend millions with each year) and he came back at $1.90/ft. I am putting 12x 240watt panels on the roof of my trailer and am going to need quite a bit of unistrut.

I hadn't thought about adding more corrosion resistance though, is the galvanic coating typically not enough? I don't think I've ever seen unistrut rust out, but I also live in Central California where we see about 4 days of rain per year 🙄
I don't remember if the Unistrut or Superstut website, but one of them had corrosion resistence comparisons between the different versions of their galvanized steel strut channel. Even without salty area, the accelerated corrosion testing seemed like in a couple of years there would be rust. Zwy mentions rust stains on the roof and I would like to do without that, too. The Aluminum channel is also about half the weight. In Central Cali you might need aluminum. In Central Ohio, we get a lot of rain and our climate is pretty humid about half the year.
 

K8MEJ

Owner, Off-Grid Power Systems
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K8MEJ

Owner, Off-Grid Power Systems
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Nov 23, 2020
Messages
255
Location
Central Ohio
I’d like to know if galvanic corrosion is a thing.

Do a Google search for "galvanic corrosion table". The father apart two different metals are on the table, the more galvanic activity (electron flow) will occur and more corrosion.
 

Lt.Dan

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I'm gonna call my supplier back tomorrow and get a quote on aluminum too. Id love to get aluminum, but I have to order 220ft total for both my trailer and the building I park next to, and $5/foot is wayy to expensive for me! Lol, I thought $1.90/foot was expensive just because of how much i need.... lol

My RV is already 22k lbs loaded, so adding 480lbs of solar panels and a few hundred lbs of unistrut is not that big of a deal.
 

HaldorEE

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I’d like to know if galvanic corrosion is a thing. I was an avionics technician a long time ago for a few years and remember being taught to look for it and it was a bad thing, but never remembered actually seeing it.

I think in part, that is because of all the effort put into building the equipment to make sure that it was the same metals. So, I never got to see dissimilar metals on the equipment I work on corrode, but we did have an example of a bolt an aluminum bolt and steel washer with galvanic corrosion in the shop. I saw this raised as a concern with dissimilar metal installations on solar with aluminum mounts and stainless steel bolts, but the guy reported back after a year on the roof, no sign of corrosion.
Add salt water or current flow through the dissimilar metal connection and the metal can just magically disappear. And that is a really good reason to not use structural metal elements as conductors.

Nobody that was in the navy will ever doubt the reality of galvanic corrosion.
 

Bob B

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Add salt water or current flow through the dissimilar metal connection and the metal can just magically disappear. And that is a really good reason to not use structural metal elements as conductors.

Nobody that was in the navy will ever doubt the reality of galvanic corrosion.
Hence, the use of gallons and gallons of red lead.
 

swill4wd

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Jan 14, 2021
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I bought my aluminum strut channel at McMasters-Carr, Shipping was a bit high though
 

Lt.Dan

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I just got a response from my supplier for aluminum unistrut and he came back at $4.70/foot delivered. Maybe I'll just do my RV in aluminum and the metal building with galvanized...
 

JoeHam

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Here is an example using aluminum angle:

 

Lt.Dan

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How is everybody attaching the solar panels to the unistrut? I like the idea of THESE with spring nuts.

I will be mounting most, if not all, of my panels on my RV parallel to the unistrut, and i think I will just laser cut 12ga stainless steel brackets that bolt to the unistrut and to the panel. But on the metal building next to me, I will be mounting all the panels perpendicular to the unistrut, and using those Clamps linked above would be perfect.
 
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