Panel came loose

[Geokilroy]

Just a word of caution: Check your solar panels often. I was setting up for an outing with my Class C. I happened to look up at my roofline. My one solar panel looked odd. It did not look quite right. The front corner seemed tipped up a bit. Not a lot but it looked off a little. When I got up there on a ladder, the front bracket had come loose from the roof but was still attached to the coating of the roof by the dicor. It moved up and down about 1 1/2 inches. The screw had come out of the solid roof material. The roof coating (rubber?) was glued to the bracket with the dicor. If it had not looked just a little off I would have hit the road with the panel flopping up and down only glued to the roof coating. If it had blown off on the hwy at 60 mph someone could have been hurt or killed.

The panel has been mounted up there for about 5 years. I never thought to physically try to pull on it. Only just a quick glance to see if it looked ok from the top. It scared me to think what could have happened.

So once or twice a year check them physically not just a quick visual.

 

[HRTKD]

Most RV roofs have a decking that is about 3/8" thick (at best) made out of wafer board (aka OSB). It's not much of a surface to mount on but it works for gluing down a rubber roof. If there has been any water intrusion, the decking deteriorates and anything screwed into that area has nothing to hold onto.

All my panel brackets were positioned so that at least one screw went into the solid wood truss that the decking is attached to.

Anyhow, good that you spotted it and I agree that periodic inspections are in order.

 

[Geokilroy]

Most RV roofs have a decking that is about 3/8" thick (at best) made out of wafer board (aka OSB). It's not much of a surface to mount on but it works for gluing down a rubber roof. If there has been any water intrusion, the decking deteriorates and anything screwed into that area has nothing to hold onto.

All my panel brackets were positioned so that at least one screw went into the solid wood truss that the decking is attached to.

Anyhow, good that you spotted it and I agree that periodic inspections are in order.

My panel was mounted by the oldest RV lot in Las Vegas. They went out of business last spring due to covid. The panel was mounted into the roof truss. the screw pulled out probably due to the vibration from the dirt roads I travel on. We are going to work on it next week. I'll see if there is damage to the truss. There are no leaks showing on the inside. I am putting in strut channel for more attachment points and also going with a larger panel (from 160 to about 400 Watts). Was going to wait till spring to change but this has moved up that schedule.

 

[HRTKD]

I'm interested to hear what size screws were used. I hope you don't find any damage.

When I did my PV install last year, I had to fix the underlayment first. Gory details in my install thread:

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

 

[Geokilroy]

I'm interested to hear what size screws were used. I hope you don't find any damage.

When I did my PV install last year, I had to fix the underlayment first. Gory details in my install thread:

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

I have a question about the screws you used. When you say "self tapping" screws do you mean they have a drill like tip on them or are you using a true self tapping screw with threads that tap the threads into the material? I remember years ago when the "self drilling" screws came out.

 

[MurphyGuy]

One day a few years ago, I was reading the news about a storm system that destroyed a solar farm.. one thing led to another, and I spent a bit looking at google images of all kinds of solar farms that had been ripped apart by wind storms. (man I love high resolution images!)

Then, I noticed something.. a pattern.. In most of the photos, it was the panels there were destroyed, not the structures themselves.

I got to thinking, what could cause a panel to come loose out of those clamps? And the only thing I could come up with was a loose clamp.. the array structures weren't bent, but the panels had been ripped right off.

When we installed our panels, we torqued them down with a torque wrench to the exact specifications.. so I went outside with the torque wrench in hand and tested the few clamps I could reach without any help.. sure enough, every one of them was loose.. Not rattle on the array loose, but well below the required torque specs by more than 50%.. and some of them were just barely more than finger-screwdriver tight.

So my wife and I got out the equipment and checked the entire array and we discovered that 9 out of 10 of those clamps were all loose..

My system was a year old at the time.. The next year, I went back again to check the panels and the clamps were all good. Checked one more time last year and they were still good.

I think the aluminum compresses a certain amount after a while, and the bonding teeth built into the fastener surface work their way in a bit further, causing the clamping screw to loosen, which then makes the panels susceptible to coming loose in the wind.

Don't just tighten the one screw, go check them all...

 

[Loadtoad]

One day a few years ago, I was reading the news about a storm system that destroyed a solar farm.. one thing led to another, and I spent a bit looking at google images of all kinds of solar farms that had been ripped apart by wind storms. (man I love high resolution images!)

Then, I noticed something.. a pattern.. In most of the photos, it was the panels there were destroyed, not the structures themselves.

I got to thinking, what could cause a panel to come loose out of those clamps? And the only thing I could come up with was a loose clamp.. the array structures weren't bent, but the panels had been ripped right off.

When we installed our panels, we torqued them down with a torque wrench to the exact specifications.. so I went outside with the torque wrench in hand and tested the few clamps I could reach without any help.. sure enough, every one of them was loose.. Not rattle on the array loose, but well below the required torque specs by more than 50%.. and some of them were just barely more than finger-screwdriver tight.

So my wife and I got out the equipment and checked the entire array and we discovered that 9 out of 10 of those clamps were all loose..

My system was a year old at the time.. The next year, I went back again to check the panels and the clamps were all good. Checked one more time last year and they were still good.

I think the aluminum compresses a certain amount after a while, and the bonding teeth built into the fastener surface work their way in a bit further, causing the clamping screw to loosen, which then makes the panels susceptible to coming loose in the wind.

Don't just tighten the one screw, go check them all...

What torque values did you use?

 

[MurphyGuy]

What torque values did you use?

I used Iron Ridge UFO fasteners, which are 80 Inch/lbs

Had to spend $70 to buy a torque wrench to do it.. didn't have one in that range.

 

[HRTKD]

I have a question about the screws you used. When you say "self tapping" screws do you mean they have a drill like tip on them or are you using a true self tapping screw with threads that tap the threads into the material? I remember years ago when the "self drilling" screws came out.

Correct. Self-drilling is a more appropriate way to describe them. If you look at the HomeDepot.com site and look up self-tapping, there are items where the title on the page is self-tapping, but the box itself says self-drilling. The Z brackets all were pre-drilled. So the screw was only drilling through the rubber roof, underlayment and the truss.

 

[Geokilroy]

Correct. Self-drilling is a more appropriate way to describe them. If you look at the HomeDepot.com site and look up self-tapping, there are items where the title on the page is self-tapping, but the box itself says self-drilling. The Z brackets all were pre-drilled. So the screw was only drilling through the rubber roof, underlayment and the truss.

Thanks

 

[PerryB67]

One day a few years ago, I was reading the news about a storm system that destroyed a solar farm.. one thing led to another, and I spent a bit looking at google images of all kinds of solar farms that had been ripped apart by wind storms. (man I love high resolution images!)

Then, I noticed something.. a pattern.. In most of the photos, it was the panels there were destroyed, not the structures themselves.

I got to thinking, what could cause a panel to come loose out of those clamps? And the only thing I could come up with was a loose clamp.. the array structures weren't bent, but the panels had been ripped right off.

When we installed our panels, we torqued them down with a torque wrench to the exact specifications.. so I went outside with the torque wrench in hand and tested the few clamps I could reach without any help.. sure enough, every one of them was loose.. Not rattle on the array loose, but well below the required torque specs by more than 50%.. and some of them were just barely more than finger-screwdriver tight.

So my wife and I got out the equipment and checked the entire array and we discovered that 9 out of 10 of those clamps were all loose..

My system was a year old at the time.. The next year, I went back again to check the panels and the clamps were all good. Checked one more time last year and they were still good.

I think the aluminum compresses a certain amount after a while, and the bonding teeth built into the fastener surface work their way in a bit further, causing the clamping screw to loosen, which then makes the panels susceptible to coming loose in the wind.

Don't just tighten the one screw, go check them all...

It's common practice on the farm to check the torqued bolts a few hours into use and re-tighten them. Most are tight on the first re-torquing, and after the second perhaps only one or two need tightening. After all the bolts are tight, remove them and install blue Loctite and torque. Even steel can compress some.

In March my wife will be flying back to Minnesota from Tucson for a week with the grandkids and I'll be applying blue Loctite to our bolts.

Enjoy,

Perry