Low(er) profile mounting cross rails?

[memilanuk]

We did a pretty hefty electrical system upgrade to our slide-in truck camper (2017 Adventurer 910DB) back in November/December. Up top, I used half-height aluminum strut channel either screwed directly into the aluminum roof frame where possible, or using well nuts (for the two holes where it wasn't). I installed some Eco-Worthy tilting brackets across the rails to hold the four 215 watt panels. The brackets are quite a bit wider (28") than the panels (~25") and the underlying rails (I forget what the exact spacing is - maybe 20"?) so they are sort of cantilevered over the inner rail by 4-5".

The goal wasn't so much being able to tilt the panels for increase solar 'harvest' as it was being able to get under the dang panels for roof maintenance, etc. without having to unbolt everything. Seemed like a good idea when I ordered, but in actual practice... the brackets sat a *lot* higher than I'd anticipated. Given that I'm not planning on getting under the panels all that often, I'm re-thinking whether I should replace those brackets with something that rides lower. I was considering getting some more low-profile / half-height strut channel and bolting the panels to that, and then attaching the upper/cross channel to the lower channel... but I'm a little concerned about being able to get my hands under there (especially on one of the panels, there is very little room between the edge of the panel and the center roof fan) to reach those spots where the panel cantilevers over the inside rail. A full-height strut channel would still be about half the height of those dang brackets, so there is that...

Thoughts? Suggestions?

 

[jberger]

Posting a couple of pics would help us visualize what you are dealing with.

 

[memilanuk]

 

[rmaddy]

The height of the panels in the pictures looks good. It will help avoid any shadows from the fans and other roof protrusions. The air gap will also help with cooling.

In the last picture is that a wind block across the front of the panel? If so, that's good.

 

[memilanuk]

Yeah, that right front panel ended up sitting a bit further forward than I had planned, due to the bathroom skylight. Not quite all the way to where the steep slope of the nose starts, but close. So I 'fabricated' the air dam out of some roof flashing from HD ?

 

[jberger]

I can understand the desire to get them a little more flush, but I think it's fine the way they are. You have easy servicing, cooling from below and they look like they are solid as a rock.

If you want to clean up the side profile, you could build out a little "goat rail" that would obscure the sides. They are normal on higher end coaches since they hide the roof clutter but it's a lot of work and $$$ for something only you probably notice. I bet no one else even realizes they are up there.

I'm working on my plan to hide the panels in line with the goat rails on our bus. I'm going to picture frame them between the rails, just need to decide if I'm going to attempt a tilting actuator or just overpanel. I know I should just over panel, but I want the tilt. . .

 

[memilanuk]

They're a little more noticeable from a distance, oddly enough.

Had a bit of an "aw crap" with the supplied hardware. I upgraded all the mounting hardware *except* the cheezy serrated flange nuts holding the panels to the rails. Which vibrated loose on the first long trip (granted, the 60-70 mph cross winds probably didn't help)...

Hence the reassessment of the whole mounting system. I will definitely be upgrading the hardware and "going gorilla" tight on them this time ?

 

[rmaddy]

The proper use of split washers should stop any issue. Locktite wouldn't hurt either.

My trailer has about 7000 miles of towing on it with the solar panels on the roof. I checked all of the panel mounts recently and not a single nut was loose (other than the one doing the checking ). Lots of wind and bumpy dirt roads. All of my panel connections use a split lock washer under the regular hex nut. Of course proper torque helps too.

 

[memilanuk]

Oh, they were *plenty* tight. I'd thought that set of bolts looked a little... puny... but figured it'd be fine. Not so much. One panel came off entirely, and just to add insult to injury, it landed in the middle of another panel on the way off.

 

[Browneye]

You lost a solar panel off your roof?

 

[memilanuk]

Essentially, yes. It was there when we pulled out of the gas station in the early morning. Wasn't there after we got thru a section with high winds and finally pulled into the next rest area.

 

[Browneye]

1/4-20 fasteners are adequate, but should have spring washers at a minimum, nylocks recommended. Or locktite.

A fellow in CA lost a panel off the roof of a motorhome and it hit the car behind him, taking out the windshield, which caused the car to crash and kill the driver. He's in jail. I was just shocked, made me rethink how those panels get connected.

If there's ANY question at all, a tether cable to a secure fixture is also recommended.

The cross channels as you describe is what I did - locktited into strut nuts on the longitudinal channels. The panels sit about an inch and a half off the deck. The cross channels are bolted to the panel frame with 1/4-20 SS bolts into strut nuts with blue locktite.

 

[memilanuk]

Yeah... and how many 'tethers' do you ever see commercially installed?

Zero.


The panels were already bolted to cross bars, bolted to strut channel, and screwed into the metal frame of the roof. From extremely painful discussions with the factory about their methods, I can say with a fair degree of certainty that these were secured better than if they were installed by the OEM.


Tethers aren't magic - they're tied to the same frame as everything else is - and subject to coming loose and/or failing just the same.

 

[Browneye]

Worth a read:

Solar Panel Mounts for Vehicle Mounted Systems

The best solar panel mounts for off grid vehicle mounted systems

www.mobile-solarpower.com

Notation about tethers at the bottom of the page. I didn't use them either. [shrug]

 

[memilanuk]

Sure. It's functionally the same as any other unsecured load, which will get your tit in the proverbial wringer in pretty much any state. Whether the law allows any wiggle room between obviously unsecured, like not putting netting over yard or construction waste in the back of a truck or trailer, vs. something literally ripping off in extreme weather conditions is probably something that varies from locale to locale, and/or how good of a lawyer you can afford.

That said, you don't see anyone adding a tether to their kayak on the roof of their SUV, or the spare tire carrier on the back of their Jeep. That blurb is there as a CYA clause, as far as I'm concerned.

Now, back to the actual topic at hand.

I'd seen your strut channel example... and that's pretty much what I'd *like* to do... but the problem I have with implementing that in my situation is that on at least one side, the connection between the channel on the roof and the cross channels is *under* the panel itself, and the room for fingers and tools gets pretty tight. Maybe with a couple double-jointed ratchets and such...

 

[Kapow_Network]

Worth a read:

Solar Panel Mounts for Vehicle Mounted Systems

The best solar panel mounts for off grid vehicle mounted systems

www.mobile-solarpower.com

Notation about tethers at the bottom of the page. I didn't use them either. [shrug]

I'd not used "commercial customs" as a safety standard. Plenty of commercial practices that are later proven unsafe (by that time often parties are in court and someone has died or been seriously injured). I think at one time it was commercial practice to transport people in blimps filled with explosive gas... The Hindenburg explosion https://en.wikipedia.org/wiki/Hindenburg_disaster#/media/File:Hindenburg_disaster.jpg led to changes. This is not the only example of commercially accepted practices later being found unsafe.

If I were in the car behind you, and one of your panels fell off and injured me or killed one of my passengers (possibly family / friend), I'd sue. Even if I wasn't hurt, and didn't want to sue, but my car veered into another, and property or lives were damaged or lost, my insurance company would likely get involved, and sue the person whose panel fell off. This is not to mention the idea of criminal charges (apparently someone's gone to jail over this very type of thing... Ever spent a night in jail? Would you pay $20 for an extra cable or line to avoid that chance even if it's slight...? Ever speed and/or drive through gusty winds (for example on California Grapevine / highway 5 - then stress about a new sound you're hearing on your roof? ).

While it still may be worth using a tether, possibly a grounding wire or cable could serve both purposes (in a small wind / pressure situation). One other benefit of an extra cable or tether to consider: even if a thief has an angle grinder, if they sees one or two extra or complicated wires or tethers on your rig, he or she may move to the next one.

Whether commercially done or not, I admit that grounding and/or tethering do not appear fun. Step 1 seems to be focus on good tight connections in the first place.

Also, fwiw, related to grounding, when I looked up the star shaped washers, they were in metric. I looked up "what is a 1/4-20 bolt metric equivalent" and it appears the equivalent is M6x 1 .

 

[Kapow_Network]

Worth a read:

Solar Panel Mounts for Vehicle Mounted Systems

The best solar panel mounts for off grid vehicle mounted systems

www.mobile-solarpower.com

Notation about tethers at the bottom of the page. I didn't use them either. [shrug]

@Browneye - Although you didn't use a tether, the "ten times" strength and over-engineering you did for a secure fit is a good example of what appears (at least from the other thread

Old RV - New PV's With Strut-Channel Mounting

I'm new here, starting a new thread on my 430W installation, so I can ask questions when they come up. This forum has been a wealth of information. I have also been scouring the 'net for, and learning about, LiFePo4 batteries as well. I'm not sure where I first saw strut channel mounting for...

diysolarforum.com

to be an installation that likely goes beyond what most commercial installers would do. Very nice looking install.