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-boun...@lists.re-wrenches.org] On Behalf Of Ray Walters Sent: Tuesday, January 10, 2017 2:31 PM To: RE-wrenches <re-wrenches@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 _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.htm l List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
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