[RE-wrenches] Lighter tubing?

[Ray]

We did a setup with the Snap N Rack rack on a roof once.  We just used 
the recommended galvanized SCH 40.  Its basically a readily available 
product.  I would be careful with other types of steel tubing: make sure 
it will fit the fittings.  We actually retrofitted a Snap N Rack to some 
existing pipe ground mount racking, and it turned out to be a slightly 
different diameter. Big pain.  2nd, make sure its galvanized, which can 
also slightly change the fit. 3rd,  if the snow load is 100 lb/ sq ft, 
your total array loading might be over 30,000 lbs.  Is saving a few 
pounds on the steel really worth considering?  Seems like your post 
bases on the roof are going to take quite a bit of engineering to 
support the snow load.

Also, final note, the Snap N Rack setup doesn't do very good with uplift 
wind loading.  It just attaches with pinch bolts, so we had our one roof 
rack get sucked off the roof in a hurricane. We drilled holes and 
through bolted on the replacement array, but I'm sure we violated the 
Snap N Rack 10 commandments by doing that.

I would consider other racks that might get the tilt with separate rows, 
and be overall lower to the roof?  Possibly a ballasted system?

Ray Walters
Remote Solar
303 505-8760

On 7/26/21 7:15 PM, Dana Orzel wrote:
>
> Hey all!
>
> I am proposing a [20] module, 35˚ tilt up array mounted on a flat roof 
> in snow country - Central Idaho. Its in town, trees behind & off to 
> the side a ways.
>
> The SnapnRack design calls for [21] Pieces of 1 ½” x 21’ sched 40 pipe 
> +/-. I am trying to understand the need for sched 40 pipe on the 
> vertical components of this array. Though if the horizontal members 
> could be switched over to tube too that would be a big savings on 
> weight. I hope to eliminate the sched 40 for steel tube [stronger 
> metal thinner wall].
>
> Without reinventing the wheel, has anyone approached this issue & how 
> did you address it?
>
> Suggestions on beefy array systems that are lighter?
>
> Spec.
>
> [20] – Q-cell 340 watt modules.  5 columns of 4 modules.
>
> Snow-Load - 100 PSF.
>
> Tilt - 35˚ – The back & sides will be shrouded up to module on 
> vertical members to prevent wind uplift.
>
> Wind - 90 MPH/3 sec microburst [though IF, this ever happened there 
> would be trees & garbage cans flying.]
>
> Sched 40 -1 ½” pipe is 2.72#/ft.
>
> 1 7/8” steel tube is 1.25#/ft.
>
> Maybe we all use schedule 40 pipe because that’s what we have always 
> done & locally available. Isn’t that’s what called recycled ignorance? 
> Looking for options. In todays world marketplace I am questioning this 
> approach.
>
> Thanks in advance.
>
> Dana Orzel                              Great Solar Works, Inc.
>
> *C - 208.721.7003                       dana at solarwork.com*
>
> Idaho Contractor - # 028765 Idaho PV # 028374
>
> NABCEP # 051112-136 www.greatsolarworks.com 
> <http://www.greatsolarworks.com>
>
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