wind load specification

iam2sam

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Sep 24, 2020
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Hello. First post, so please go easy ;) This question *is* tower related, but somewhat less strictly radio related, so I'll try to be brief. I am thinking about building a tilt-up tower to get a small photovoltaic panel clear of tree shadow on some off-grid property I own. I've reviewed at least three plan descriptions (including one for the "tilt-up then crank-up 50' tower" plan by Ben Stone that no longer seems to be available) and each one specified design maximum wind load solely in terms of surface area (typically, in square feet). Maybe I'm missing some fundamental assumptions that don't require mentioning in the amateur radio community, but that seems woefully inadequate to me. At minimum, shouldn't there also be a maximum wind velocity/gust specification, e.g. "6 sq ft @ 40 MPH with 70 MPH gusts", or something similar? I'd also be interested in learning if the surface area specified is typically for the payload only or whether the surface area of the tower structure itself is expected to be factored in by the builder. Thanks for any insights you can provide.
 

mmckenna

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Tower specs will show a maximum wind load at a specific wind speed. If it's missing the wind speed, then I'd question the validity of the design.

The wind load specs are for additions to the tower, the wind load of the tower itself should already be included.

When you do your wind load calculations, you'll need to not only figure in the solar panels, but also any supporting brackets, cabling, etc. Usually you need to figure in ice loading, as ice will add to the weight and the amount of surface area.
 

iMONITOR

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Make sure the solar panel itself can hold up in sustained winds and gust. Normally they're designed to be mounted flat on a roof or a substantial mounting structure on the ground.
 

mmckenna

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Is there a reason to get solar panels up that high like too many shade trees, etc?
My sister/brother in law are going through the same thing at their cabin up near Mt. Shasta. Too many trees, and in the winter the sun is low on the horizon. Keeping the batteries charged due to limited amount of light hitting the panels is a challenge. Moving the panels higher up helps quite a bit.
 
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