How to calculate wind impact to DIY solar panel array frame?

Question

I'm trying to figure out the calculation for amount of force against the poles/ground I have going up out of the ground, to hold an array of 3 solar panels (9ft by 5ft combined roughly), where each panel is 40lbs, and frame material not 100% defined but likely wood/metal combo, with concrete poured to anchor to (but, again, I'm not sure how much force will be against the panels from wind, versus how much I need secured to the ground).

Highest wind here recorded was 111mph with 123mph gust wind. I read solar panels can handle 140mph winds, however, I need to figure out a strong enough frame for the 3 panels in the wind.

How would I approach calculating this? I have no wind force calculation experience, and I didn't find immediately clear math to solve for it on google.

Answer 1

From your units, I'm assuming you're based in the US ? Have a look at the skyciv online wind calculator : https://skyciv.com/wind-load-calculator/

It has support for sussing out wind loads to ASCE7-16. The steps are fairly straightforward but there are some required parameters that may need googling on your end if you're not a structural engineer/have not designed structures for wind loads before.

Note that getting the loads alone will not be enough. You'll also need to ensure that your assembly is stiff enough to not vibrate too much under wind (i.e., the typical gust frequencies in your locality should not match up with the natural vibration frequency of your frame assembly). I've never dealt with solar panel assembly design before, but I believe stiffening of the mounting frame can help alleviate this. I would recommend going with steel framing instead of wood primarily for this reason.Use galvanised steel if available to do away with corrosion risks (otherwise stainless steel - but that will likely come at a premium).

Edit: If you're not a licensed PE yourself, I would also recommend getting in touch with a licensed structural/mechanical engineer to certify your frame/design one for you. This will add to the cost but will give you peace of mind and act as a warranty of sorts on the framing system (which would otherwise be your own risk entirely).