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Thoughts on solar array snow guards or eave setback, zone 4A?

andy719 | Posted in Energy Efficiency and Durability on

I’m about to have a solar array installed on my roof, but starting to worry about snow avalanche issues.  Does anyone believe snow guards are a necessity in zone 4a (DC suburb), or have advice alligning the leading edge of the array with the eave/gutters?  I realize most of our typical small amount of snow will just blow away without issue, but we do have the occassional 8-12 inch deep overnight snowfall that may build up and come crashing down in the morning.

My particular largest portion of the array that is designed to go from eave to ridge (minus fire department clear space at ridge) is roughly 16′ wide and 18′ tall.  That feels like a sizeable glacier to me to come crashing down two stories onto my deck below, even if it is only once every few years. The roof is composite shingle with a 7/12 pitch.

Should I install snow guards here?  Also, is there a rule of thumb if I don’t install snow guards, for how tall the racking needs to be, or how far the setback distance needs to be, so any avalanche doesn’t land directly onto the gutter? 


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  1. jadziedzic | | #1

    Our previous home here in New Hampshire had 33 panels on our south-facing roof -around 15 x 25 in dimension. We do see rather big snowfalls at times, with moderate a more common occurrence. The bottom edge of the panels was about 12 inches from the bottom edge of the roof, and when we had a "solar avalanche" the snow would have enough momentum to mostly clear the gutters at the edge of the roof. We did not have any damage in the seven years the panels were installed before we sold the house.

    The solar panels typically self-cleared part-way through most snow events, and the cascade off the roof was never in large chunks, more like a loose-packed sheet. It wasn't uncommon to have a 4-6 inch deep layer on the panels for a short while after the snow stopped falling.

    The one thing to keep in mind is that when the snow *does* impact the ground it will tend to pack together rather densely, especially if you're dealing with a two-story house, so if you want to remove the snow from where it lands it helps to do so fairly quickly after it has fallen.

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