[RE-wrenches] Solar World Wind Damage

[Ray Walters]

Hi William;

Your link had a glitch,  I think this should be it?
http://www.millersolar.com/MillerSolar/case_studies/Wind_damage/_wind_damage.html

We have DP&W's high wind option which bumped the pole size from 4" to 6" 
along with heavier hardware throughout.  I haven't been to the site yet, 
but the techs were reporting just the module failed and the rack is 
still good.  I'm going up next week and I'll try to figure this out.  
This site also has a funnel effect as you mentioned.  Higher ridges to 
the North and South, and this smaller peak between with our rack almost 
right at the top.
Roof mounts actually do seem to be much better; the wind doesn't get 
behind it, and if the array is set back from the edge,  the side edge of 
the array isn't getting pummeled.
Our failure occurred with an angled wind, not perpendicular.   Your rack 
failures look also to have had uneven loading: the way it twisted that 
top rail off. I almost wonder if these racks aren't hitting some 
resonance that's causing the rack to twist and torque back and forth 
repeatedly.  You can grab the corner of the array and "pluck" it, then 
watch it bounce back and forth: that's the simple way to determine its 
harmonic resonance.

R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760

On 1/10/2017 6:26 PM, William Miller wrote:
> Ray:
>
> I can't say I have a solution to your problem, but I can share some photos
> of two similar failures in case you can glean any information from them.
> See:
> http://www.millersolar.com/MillerSolar/case_studies/Wind_damage/_wind_dama
> ge.html
>
> The first failure is a Zomeworks.  On the same exact spot we tried a DPW
> TOP.  Neither could withstand a funnel effect provided by the topography.
>
> At the same location we installed a roof mount as well that has never
> failed (to my knowledge, we don't service that customer anymore).
>
> I think if you have terrain that is tilted in the correct direction a
> mount that hugs the ground is best.  That is a lay opinion, however.
>
> William
>
>
>
> Lic 773985
> millersolar.com
> 805-438-5600
>
> -----Original Message-----
> From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On
> Behalf Of Ray Walters
> Sent: Tuesday, January 10, 2017 2:31 PM
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
> Subject: [RE-wrenches] Solar World Wind Damage
>
> Greetings All;
>
> I just had the dreaded call from one of my higher profile commercial
> clients: a remote radio repeater station had modules ripped off the frame
> by high winds.
> Two  SW285s were damaged.  The wind was strong enough to rip right through
> the aluminum side rails.  We had used the proper stainless 1/4"
> bolt hardware with washers on the inside, etc.  All the hardware was still
> tight, it just tore the aluminum past the washers.  This is not a top down
> clamp system, but uses bolts through the mounting holes on the back of the
> module.  This was all on a DP&W rack with high wind option.
> In 20 years in business, I've never seen that happen.  Is there a contact
> at Solar World?  I'm not getting through on the tech support line I have.
> First, I need to know what the wind rating is on the modules blowing from
> the back side, and Second, a suggested fix for the remaining modules.
> One module was completely ripped from the frame and thrown 30 yds (total
> destruction), a 2nd one has cracks in the Aluminum, but has not let go
> yet.  I was thinking of adding some angle aluminum on the inside to beef
> it up.  IMHO, the frames are pretty thin aluminum compared to older
> modules.  I'll share some pics when available.
>
> As always thanks in advance for your comments,
>
> --
> R.Ray Walters
> CTO, Solarray, Inc
> Nabcep Certified PV Installer,
> Licensed Master Electrician
> Solar Design Engineer
> 303 505-8760
>
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