FYI: Pascals (Pa) downforce load compared to psf

[DaylanDarby]

For Your Information:

I am doing my own install and came across two different rail to frame (Canadian Solar) requirements: "Downforce load <= 2400 Pa" and "2400 Pa <= Downforce load <= 5400 Pa" (for rails parallel with the short side). In my case (CS6P) the range is 240-410mm or 340-410mm (respectively).

I had to look up Pa, and assuming the information on here is correct then 101325 pascal (Pa) equals ~2116.2 pounds-force per square foot (psf). If I have done the math correctly then 2116.2*2400/101325 = ~50 psf.

Since my snow load (live = 30 psf and drift = 43 psf) is less than 50 psf, it appears that I have the option of placing the rails (relative to the panel short edge) 9.5" (240mm) to 16" (410mm). However, once I see where the shingles line up I will put it in the ~13" to 16" range if possible.

Posting this in case anyone else wonders what "Pa downforce load" means and how to translate it into psf.

[J.P.M.]

For Your Information:

I am doing my own install and came across two different rail to frame (Canadian Solar) requirements: "Downforce load <= 2400 Pa" and "2400 Pa <= Downforce load <= 5400 Pa" (for rails parallel with the short side). In my case (CS6P) the range is 240-410mm or 340-410mm (respectively).

I had to look up Pa, and assuming the information on here is correct then 101325 pascal (Pa) equals ~2116.2 pounds-force per square foot (psf). If I have done the math correctly then 2116.2*2400/101325 = ~50 psf.

Since my snow load (live = 30 psf and drift = 43 psf) is less than 50 psf, it appears that I have the option of placing the rails (relative to the panel short edge) 9.5" (240mm) to 16" (410mm). However, once I see where the shingles line up I will put it in the ~13" to 16" range if possible.

Posting this in case anyone else wonders what "Pa downforce load" means and how to translate it into psf.

And hopefully, they won't be designing a structure they may wind up living under or near while wondering.

FWIW, depending on how rigorous you may want, or are required to be by any permitting authority, all loads, including live loads (wind, seismic(?), workers, other ?) usually need to be considered in some combination(s) with static (sometimes called dead ) loads (snow, equipment, etc.) depending on service, location and local jurisdiction and common sense. I'd also, probably as more of a check, make sure the rails/racking are attached to something that will take the potentially imposed loads and I wouldn't leave uplift or lateral forces out of consideration.

If anyone is designing a structure and they wonder what "Pa downward force" means I'd like to know so I could find out where such a structure is located and for reasons of personal safety be sure to avoid it.

See unit conversion tables, S.I. units <<-->> Customary units.