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  • Panel placement near bottom of roof

    I've heard two perspectives on installing solar panels on sloped roofs in snow country. One opinion is to put the panels slightly overhanging the lower edge of the roof so snow will slide right off the panels and not pile up on the roof. Another opinion is to pull the panels back a foot or so, so that when the snow slides off the panels, it won't avalanche so badly and the fall will be slowed by that foot of asphalt roofing.

    What are your opinions, experiences, and thoughts?

    Thank you.
    7kW Roof PV, APsystems QS1 micros, Nissan Leaf EV

  • #2
    Hmm. I was just thinking about this, but my mind went in a different direction. I'm going to modify some roof snow guards to fit at the lower edge of the panels, to break the sheets up when they slide. My first thought was to anchor it to the racking, but really they should be anchored independently so a large ice sheet doesn't damage the array.

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    • #3
      You don't want a snow slab to trash your roof eves or gutters. But code may not allow cantilevering panels over the eves.
      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

      solar: http://tinyurl.com/LMR-Solar
      gen: http://tinyurl.com/LMR-Lister

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      • #4
        Anything hanging over the end of the roof will need to be added to the "uplift" wind calculation per code.

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        • #5
          Originally posted by SunEagle View Post
          Anything hanging over the end of the roof will need to be added to the "uplift" wind calculation per code.
          If the added items are affixed to the racking, the racking and the racking attachments will need review with respect to any additional wing loading(s). Such considerations may include the roof at racking to roof contact points.
          If the additional materials are attached to the roof rather than the racking, the the roof may need some considerations for the effect of the added wind loading.

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          • #6
            Originally posted by J.P.M. View Post

            If the added items are affixed to the racking, the racking and the racking attachments will need review with respect to any additional wing loading(s). Such considerations may include the roof at racking to roof contact points.
            If the additional materials are attached to the roof rather than the racking, the the roof may need some considerations for the effect of the added wind loading.
            Good point. I know that in Florida just about any thing handing over the edge is watch carefully due to hurricane wind speeds. Even most insurance companies prefer hip style instead of gable style roof that minimizes over hanging soffits.

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            • #7
              I live in MN and my panels have around a 12" setback from the gutters. When there is snow build up and it comes sliding off it drops 2 stories and hits the deck among other things in an impressively thunderous fashion. Never had an issue with the snow hitting or damaging the gutters on its way down.

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