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Re: Photovoltaic panel weights

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Thanks for the idea on treating the panel as a slippery slope. The project is located in interior Alaska and coming up with a design snow load has been problematic. The roof slope is 4:12, so the roof slope factor looks like it will be equal to 1.0, the array is located over an unheated portion of the structure.

On 3/17/2014 4:48 PM, Michael James wrote:

Solar panels tend to shed snow (slippery surface). Depending on your
roof material and slope (e.g. asphalt shingles), you might realize a snow
load reduction in the area of the panels compared to the bare roof if the
snow is free to slide off and go elsewhere (panels close to eaves perhaps) any snow shed from the panels has to go somewhere however, so you could have a drift wherever any such snow might end up (lower roof, break in slope etc). Then again snow downslope on a non-slippery roof might hold it all on the panels if the snow is deep enough and panels close enough to the roof. Conversely you could have your panels effectively acting as snow bars and holding snow upslope on an otherwise slippery roof (eg standing seam). These types of things come up from time to time on existing roofs that were not designed for solar panels. Panel installation has the potential to effect the snow loads and their distribution to the underlying roof structure. - Mike

Drew Morris <dmorris(--nospam--at)> wrote:

Truncated 875 characters in the previous message to save energy.

Drew Morris, PE*| Project Engineer
BBFM Engineers, Inc. <>
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