Roof or pole mount?

Vivien
Vivien Registered Users Posts: 6 ✭
in General Solar Power Topics #1
Hi,

Has anyone ever heard of a really heavy wind/hurricane pulling a solar panel off a roof, and thus harming the roof. We have a standing seam metal roof and are considering whether to put solar panels on the roof or pole mounted. We're a little worried about possible danger to our roof in extreme weather.

What do you think?

Thanks,

Vivien
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Comments

  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #2
    Re: Roof or pole mount?

    If your roof is good, the solar array will be good. The weakest part of a standing seam solar installation is the nails holding the steel roof sheets down. Chances are it is hard to tell what nailing pattern was used unless you can see them sticking through into the attic. Standing seam clamps are the way to go with a solar array as there are no roof penetrations and are very cost effective. Use one on every standing seam according to the manufacturer. Biggest hurricane problem you could have is flying debris.
    If you want wind problems, go the pole mount route. Talk about a sail.
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  • Vivien
    Vivien Registered Users Posts: 6 ✭
    #3
    Re: Roof or pole mount?

    Thanks for the info. Just curious--not sure what you mean about pole mounts in a hurricane. Thanks again!
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #4
    Re: Roof or pole mount?

    i don't think it would be the pvs on your roof you'd need to worry about as debris from trees and other homes will surely be picked up and hurled at your home whether you have pvs or not. the pvs may actually stand in the way of that debris from damaging your roof, but that means damaged pvs being they would be between the flying debris and the roof.

    what solarix was saying is that if the pvs on a pole mount would break off at the pole it would be one huge sail. i don't think i've heard of one of them allowing the whole skeleton of the mount to break off though. roof mounts are attached at more than one point.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #5
    Re: Roof or pole mount?
    Vivien wrote: »
    Thanks for the info. Just curious--not sure what you mean about pole mounts in a hurricane. Thanks again!

    With S-5's on a standing seam roof, the wind has only a narrow opening to get underneath the array, but with a pole mounted array, the whole surface of the array is in the wind with nothing behind it. Wind loading is a significantly larger problem for pole mounted vs. rooftop mounted arrays.
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,894 ✭✭✭✭✭✭
    #6
    Re: Roof or pole mount?

    As long as the design is right you can do most anything! The downside of a roof mount is if the design is not right you end up with holes in your roof.

    It is just a no brainer (for me) to stay off the roof if there is a choice.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #7
    Re: Roof or pole mount?
    Dave Sparks wrote: »
    As long as the design is right you can do most anything! The downside of a roof mount is if the design is not right you end up with holes in your roof.

    It is just a no brainer (for me) to stay off the roof if there is a choice.
    But the choice is sometimes complex. For one thing, roof mounting is generally significantly less expensive than ground mounting, especially since you typically will have to fence around a ground mounted system.
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,894 ✭✭✭✭✭✭
    #8
    Re: Roof or pole mount?
    ggunn wrote: »
    But the choice is sometimes complex. For one thing, roof mounting is generally significantly less expensive than ground mounting, especially since you typically will have to fence around a ground mounted system.

    I never have fenced a solar system offgrid where any of my systems are. If I ever have to do that I will just reccomend that the client move farther out from the "big city". I am usually envious of some of my clients locals. Quite a few of them being on mountaintops would never want to compromise their roof and their power source in one failure. Or, they only do this once! It is often expensive to do things the best way.

    I do see your point but I think we are in different situations, or as usual I am misunderstanding the thread....
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    #9
    Re: Roof or pole mount?

    Another problem ,if you live where you get a lot of snow, you cant get the snow off the panels on the roof. In my area a lot of roofs have caved in because of too much snow. I tryed it a couple times not cleaning the snow off and it didn,t come off by itself. So when it snows a lot I get up in the morning and clean the snow off before I do anything else. :Dsolarvic:D
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: Roof or pole mount?

    That snow-on-the-panels problem doesn't exist everywhere. Up here with a winter angle of 72 degrees it is highly unlikely any snow is going to accumulate on the panels! ;)
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  • abrockca
    abrockca Solar Expert Posts: 72 ✭✭✭✭
    #11
    Re: Roof or pole mount?

    We're in a geodesic dome, so roof mounting was an immediate "no way".

    We are thinking of replacing our panels (what good is a long warranty when technology is advancing so quickly that after 5 or 6 years we start lusting after new panels?<smile>)... our fixed array is easy to get to and would be a simple replacement. Our tracking array would need new rails and is so high up that it's going to be difficult. So it would make more sense to put more powerful panels on the tracking array. But the fixed array is much easier.

    So roof mounted - think about not just ease of getting rid of the snow, but also replacing or working on the panels. We had a panel come off the tracking array in a storm (vendor who installed it: "That has never happened before!" we get a lot of that from our vendors...I'm beginning to think we should be a testing ground for equipment...) ; luckily the vendor came out and did all the replacement work.

    After we get a few inches of snow, we give up trying to get it off the panels and just wait for nature to take its course; that's what generators are for....

    Anne
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #12
    Re: Roof or pole mount?
    Dave Sparks wrote: »
    I never have fenced a solar system offgrid where any of my systems are. If I ever have to do that I will just reccomend that the client move farther out from the "big city". I am usually envious of some of my clients locals. Quite a few of them being on mountaintops would never want to compromise their roof and their power source in one failure. Or, they only do this once! It is often expensive to do things the best way.

    I do see your point but I think we are in different situations, or as usual I am misunderstanding the thread....
    Even out in the sticks you sometimes have to fence around a ground mounted system. I was putting up a system out on a ranch and before the fence crew did their work, cattle got into the arrays. They broke three modules and severely bent a couple of rails. Also, in some cases an inspector will fail a ground mounted system which is not fenced in because the conductors and connectors are easily accessible.

    That of course does not mean that a fence is always necessary, but for a variety of reasons fencing around ground mounted systems is quite often done. YMMV.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #13
    Re: Roof or pole mount?

    i'll agree with ggunn here as there are other animals that can do them in too. one such possibility is deer. i'd make the fencing more visible to such an animal as they will then avoid it if seeing it in enough time if in full stride. the fence itself may not stop a deer in full stride and as i've seen then leap quite high is why i mentioned the visibility.
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  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    #14
    Re: Roof or pole mount?

    Niel, I don,t have a fence but started thinking about the same thing you mentioned as I saw a couple experiences with deer at work. I worked in a foundry and we had a big styrophone pattern with about 16 inch square holes in it. A deer went in the pole building and my boss went in the pole building to chase it out. The deer jumped thru one of those square holes and didn,t make a mark on the pattern. Big foundrys have molding pits to make the molds in. There is a pit that is about 12 feet deep and there were 2 guys in the pit making a mold and someone chased the deer and it got in the pit. They thought they might have to shoot it but it jumped out of the pit on its own and it didn,t hurt any of the guys in the pit. I had a pine tree the deer worked on every year till it got big enough that they leave it alone. Hope they don,t think my solar panels are a pine tree. :Dsolarvic:D
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #15
    Re: Roof or pole mount?
    solarvic wrote: »
    Niel, I don,t have a fence but started thinking about the same thing you mentioned as I saw a couple experiences with deer at work. I worked in a foundry and we had a big styrophone pattern with about 16 inch square holes in it. A deer went in the pole building and my boss went in the pole building to chase it out. The deer jumped thru one of those square holes and didn,t make a mark on the pattern. Big foundrys have molding pits to make the molds in. There is a pit that is about 12 feet deep and there were 2 guys in the pit making a mold and someone chased the deer and it got in the pit. They thought they might have to shoot it but it jumped out of the pit on its own and it didn,t hurt any of the guys in the pit. I had a pine tree the deer worked on every year till it got big enough that they leave it alone. Hope they don,t think my solar panels are a pine tree. :Dsolarvic:D
    In our case we found that cattle love to scratch their butts on metal corners.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #16
    Re: Roof or pole mount?
    ggunn wrote: »
    In our case we found that cattle love to scratch their butts on metal corners.

    i would venture to say to keep everything rounded as best as you can then. it may help to put a scratching post elsewhere for them so they don't settle for the fence. not only would the fence get messy, but there would be quite the minefield around there.:cry:phewww
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  • TnAndy
    TnAndy Solar Expert Posts: 249 ✭✭
    #17
    Re: Roof or pole mount?

    I went pole mount, simply because I wasn't willing to cut the trees that shade my roof, and are worth a LOT in terms of summer cooling.

    I stripped the trees off a hillside out from the house, and put my arrays there. Plus, putting them on poles allowed me to build tracking mounts.

    ry%3D480

    ry%3D480

    ry%3D480
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