snow on panels

ws9876
ws9876 Solar Expert Posts: 450 ✭✭✭
in PV Installers Forum - NEC, Wiring, Installation #1
I want to install on my roof. the only place to mount my panels is in between the upper roof
and lower roof. I can get 45 degrees if I put the racks attached on top to the eve of upper roof and down on the upper portion of the lower roof. But snow will occasionally cascade over the surface of the panels on the way down. I am on 45 parallel. Will this hurt panels??
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: snow on panels

    Couple of things here. If you're at Latitude 45, your panel angle should be closer to 69 degrees which is good for shedding snow. See the Macslab calculator:
    http://www.macslab.com/optsolar.html

    But the real issue is the potential avalanche from the upper roof level. Yep; suddenly dropping a lot of snow on to panels (which are glass and aluminium) could have a sudden, catastrophic result.

    I'm sorry but I have no idea how to get around that problem. This really needs an on-site evaluation by someone who's an experienced installer.
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  • ws9876
    ws9876 Solar Expert Posts: 450 ✭✭✭
    #3
    Re: snow on panels

    I can mount a couple sideways on the wall between the roofs but I might get some shading....
    I might have to do a ground rack...bad news
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,023 ✭✭✭✭
    #4
    Re: snow on panels

    Or install some dams on the upper roof. You see these on steel roofs to hold snow and ice from cascading down onto people or property. It holds the stuff up and just lets it melt (in theory anyway).

    Ralph
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #5
    Re: snow on panels

    If you have a steel roof you could install snow brakes (breaks?) (dams) like ralph suggests, but I would be leery. I have found now brakes to be only marginally effective. A large cascading avalanche would be a problem to the panels.

    You could consider the energy effectiveness of installing heat tape on the upper roof. Some of the heat line semi-conductor heat tape uses no power until it needs to, and then only a small amount. You could consider running the heat tape only when it is snowing if snow is a fairly rare event.

    If snow is a common event, you really have to consider ground mount, if only to keep the panels swept..

    Tony
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