Hi Todd, I concur with your conclusion’s as we do mount on poles some as high as 15’ to bottom of modules depending on average winter snow pack, here in the Sierra around Truckee. We do have one client with taller pole mounts but he’s out of the ordinary.
Sincerely, Chris Worcester Solar Wind Works NABCEP Certified PV Installer Phone: 530-582-4503 Fax: 530-582-4603 <http://www.solarwindworks.com/> www.solarwindworks.com <mailto:[email protected]> [email protected] "Proven Energy Solutions" From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Wednesday, April 13, 2011 10:10 AM To: RE-wrenches Subject: Re: [RE-wrenches] Heavy Duty Modules? Hi Doug, I had a customer's roof mount system break modules this spring after yet another record Mount Shasta snow event. This one brought 8' in 10 days. The situation here was 15 Evergreen 190 watt modules (rated for 80#/sq ft), on a DP&W power rail mount, on a 6/12 pitch, comp roof. Ice dams were not removed so the bottom edge of 5 module's frames were peeled off the glass... without the frame's support, 2 of the module's glass broke. Evergreen did not warranty the damage. >From Evergreen: "The observed damage is attributable to weather related effects, not manufacturing or workmanship issues with the panels. You are correct, we do guarantee our panels for up to 80 pounds / sq. ft. However, that is for a uniform load. The installation manual, page 3 (attached), has the following warning: The maximum permissible loads apply to uniformly distributed wind or snow loading. Care should be taken to avoid mounting panels in areas that are prone to drifting snow, icicle and/or ice dam formation." I have come to the conclusion that the only real way to mount PV modules in heavy snow country is on a pole mount with a steep winter angle and enough ground clearance (minimum 6' from the bottom edge of the array to the ground) to allow the snow to keep sliding off the array all winter. A roof mount might still work, but it would need to be greater than ~8/12 pitch (not so good for summer production) and accessible to manual snow removal in those critical situations like we had here a couple of weeks ago. One of my most difficult challenges is trying to design my installations to mitigate winter snow damage. I realize very few list members have to deal with these kinds of severe conditions, but any feedback on my empirical conclusions would be welcome. Todd On Wednesday, April 13, 2011 8:44am, "Doug Wells" <[email protected]> said: > > > Wrenches, > > Can anyone recommend a panel that is built with more strength or > ability to handle greater load. > I am installing on a shallow pitched roof and am concerned about snow > build up in this particular location. > I know you guys out in the Sierra's get a lot more snow than we do. > What modules are up to the challenge? > Are there any new military spec modules like the old MSX 120's? > Any experience or guidance is appreciated. > > Doug Wells > Morrisville, VT 05661 > NABCEP Certified PV > Vermont Solar Partner > The Solar Specialists > www.thesolarspecialists.com > 802-498-5856 > _______________________________________________ > List sponsored by Home Power magazine > > List Address: [email protected] > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > >
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