What you need to know about
wind effects on solar panels

(Continued from previous page)"…no knowledgeable PE should stamp a design based on [aerodynamic wind tunnel test] results. Here’s why…”

 

First, not all wind tunnels are the same. Aerospace wind tunnels, like the ones used to test cars and aircraft, produce “smooth” wind at a constant speed. Boundary layer wind tunnels create gusty, turbulent wind. Wind flow near the edge of a building roof is nothing like the smooth wind along the floor of an aerospace wind tunnel. In fact, the test lab would have done better to mount panels on the wings of a fighter jet, and then place the whole jet in the tunnel in takeoff position. This is because powerful swirling winds, or vortices, form above the corners of flat roof buildings, the same vortices that provide so much lift for delta-wing aircraft. If you don’t test the panels under these vortices, you have no idea how much lift the panels will see near the edges of the roof. This is especially true of panels with slopes of 10 degrees or less that feature wind protection deflectors.

 

So,

Rule #1 for measuring useful wind loads on roof-mounted solar panels:
You must test on the roof of a building.

 

Later, the same guy walks up to the same wind engineer and says…

 

"My PE knew that rule you mentioned (apparently, most do), and refused to OK the use of the downforce idea in the design. But I think my project is different…

 

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Links

Solar Modules on Flat Roofs - Why Worry About Wind? (More Technical)

How to Calculate Wind Loads on Roof Mounted Solar Panels in the US

Wind Effects on Solar Panels Brochure

Renewable Energy Brochure

Renewable Energy Technical Papers