[RE-wrenches] High Snow Load on PV modules

[R. Walters]

Also, when you're calculating snow load, the load is decreased when  
on an angle. Simple Trig, the snow load is straight down(gravity), so  
if the panel is at an angle it only sees the portion of the load  
straight down. Same as you would figure wind loading with an array.  
I'll send anyone interested a sheet on how to calculate this, if  
you're not seeing it.

R. Walters
Solarray.com
NABCEP # 04170442	



On Jul 28, 2009, at 8:57 AM, Greg Egan wrote:

> My solution to snow load issues is to install modules on racks so  
> they can tilt to 90 degrees when it's snow season.  I guess it  
> depends on where you are but in the areas of Alaska where we work  
> we tell people to tilt your array to 90 in the fall and kick it  
> back to lat-15 in the late spring.  They gain some from snow  
> reflection and lose some because they're not always at the best  
> angle but they make a lot more power than modules installed under  
> the snow.
>
> We like top of pole mounts that allow for an 85 or 90 degree  
> setting for the snowy season.  We've done some installs of modules  
> on the s side of buildings where we leave them basically plumb  
> during snow season and kick them out like an awning the rest of the  
> year.  Sometimes there's a nice 2' overhang on the roof that keeps  
> the snow off the wall mounted array even if it's kicked out maybe  
> to 75 degrees or so.  Roof installs are our least favorite for a  
> number of reasons.
>
> I know the architects among us love to not see those ugly modules  
> but I generally try to convince my clients that their neighbors  
> will think they're stupid if  they see their PV panels under the snow.
>
> Believe it or not we get most of our annual sunshine in the  
> spring.  It's clear and cool.  June has more "possible" sun hours  
> but is generally cloudier so the NREL 30 yr averages show spring to  
> be the most productive for us.  Don't want to miss out on that  
> power if we can help it!
>
> Best,
>
> Greg
>
>
>  Greg Egan
>
> Remote Power Inc.
> 981 Gold Mine Trail
> Fairbanks, AK 99712
> P. 907.457.4299
>
> U.S.Distributor for Outback Power Systems and other premium power  
> equipment.
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