<font face="arial" size="4"><p style="font-family: arial; font-size: 14pt;">Hi Doug,</p>
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<p style="font-family: arial; font-size: 14pt;">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.</p>
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<p style="font-family: arial; font-size: 14pt;">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.</p>
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<p style="font-family: arial; font-size: 14pt;">From Evergreen:</p>
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<p><span style="border-collapse: collapse; color: #1f497d; font-family: Calibri, sans-serif; font-size: 15px; line-height: 16px;">"The observed damage is attributable to weather related effects, not manufacturing or workmanship issues with the panels.</span></p>
<p><span style="border-collapse: collapse; color: #1f497d; font-family: Calibri, sans-serif; font-size: 15px; line-height: 16px;"><span style="font-family: Arial, sans-serif; font-size: 13px; color: #000000;">
<p style="padding: 0px; margin: 0px;"><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: #1f497d;">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:</span></p>
<p style="padding: 0px; margin: 0px;"><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: #1f497d;"> </span></p>
<p style="padding: 0px; margin: 0px;"><span style="font-size: 8pt; font-family: Avenir-Light;">The maximum permissible loads apply to uniformly distributed</span></p>
<p style="padding: 0px; margin: 0px;"><span style="font-size: 8pt; font-family: Avenir-Light;">wind or snow loading. Care should be taken to avoid mounting</span></p>
<p style="padding: 0px; margin: 0px;"><span style="font-size: 8pt; font-family: Avenir-Light;">panels in areas that are prone to drifting snow, icicle and/or ice dam</span></p>
<p style="padding: 0px; margin: 0px;"><span style="font-size: 8pt; font-family: Avenir-Light;">formation."</span></p>
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<p><span style="font-family: arial; font-size: 14pt;">I have come to the </span><span style="font-family: arial;"><span style="font-size: 19px;">conclusion</span></span><span style="font-family: arial; font-size: 14pt;"> 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 (<span style="text-decoration: underline;">minimum</span> 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.</span></p>
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<p><span style="font-family: arial; font-size: 14pt;">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.</span></p>
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<p><span style="font-family: arial; font-size: 14pt;">Todd</span></p>
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<p style="font-family: arial; font-size: 14pt;">On Wednesday, April 13, 2011 8:44am, "Doug Wells" <dwells@thesolarspecialists.com> said:<br /><br />> <br />> <br />> Wrenches,<br />> <br />> Can anyone recommend a panel that is built with more strength or<br />> ability to handle greater load.<br />> I am installing on a shallow pitched roof and am concerned about snow<br />> build up in this particular location.<br />> I know you guys out in the Sierra's get a lot more snow than we do.<br />> What modules are up to the challenge?<br />> Are there any new military spec modules like the old MSX 120's?<br />> Any experience or guidance is appreciated.<br />> <br />> Doug Wells<br />> Morrisville, VT 05661<br />> NABCEP Certified PV<br />> Vermont Solar Partner<br />> The Solar Specialists<br />> www.thesolarspecialists.com<br />> 802-498-5856<br />> _______________________________________________<br />> List sponsored by Home Power magazine<br />> <br />> List Address: RE-wrenches@lists.re-wrenches.org<br />> <br />> Options & settings:<br />> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org<br />> <br />> List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org<br />> <br />> List rules & etiquette:<br />> www.re-wrenches.org/etiquette.htm<br />> <br />> Check out participant bios:<br />> www.members.re-wrenches.org<br />> <br />></p></font>