Good afternoon; Mounting modules on 3 rails will typically increase the load carrying capacity of the array by 30% (or more). Most module manufacturers list this method in their installation manuals, or if not in the manual, they have a waiver written for that method.
Be aware that when mounting modules in a heavy snow load region that highest static snow load will be concentrated on the lowest module rail in the array. If you mount modules in landscape configuration the load will be concentrated on a long side rail and this can sometimes lead to loads above what that rail can carry. The bottom rail may require extra support, or consider shifting to portrait mount. George McClellan | Technical Sales Manager | REC Solar US +1 805 704 3226 | www.recgroup.com On Mar 27, 2022, at 9:52 AM, Jeff Clearwater via RE-wrenches <re-wrenches@lists.re-wrenches.org> wrote: Hi Blake, I'm curious why the assumption that the snow will destroy the array - how about 3 rails instead of 2 under the modules? Blake Gleason via RE-wrenches<mailto:re-wrenches@lists.re-wrenches.org> March 26, 2022 at 8:39 AM Hi all, I think there's a lot of experience on this list with PV in snowy regions. I'm wondering if anyone has ideas and/or specific hardware/racking systems to allow for easy "stowing" (in vertical or near-vertical position) or "seasonal removal" of the ground mount PV modules for the winter (snow) season? Or ideas for a completely different approach to solving the challenge I'm facing? I'm planning a new off-grid system in the Sierra (around 6000') for a small commercial community center facility. The facility is accessible and in use only during the summer months. So, I want to optimize production for the summer, and also avoid having the array destroyed by the heavy Sierra snow during the winter. To further paint the picture, here are some more details and constraints: - System size: 23kW (likely 48 Silfab 490 mods) - Must be ground mount (beautiful very tall trees completely surrounding all roof options) - Must be relatively low profile, visually. Pole mount not an option - Ideally one clean rectangular array 4x12 mods (13' x 90') or two 4x6 arrays (13' x 45') - Array tilt: 10-15 deg (summer use only, must be low-profile) There is a caretaker who has a seasonal crew, and could be trained to "stow" the array each season as long as that process is relatively straightforward. At one end of the spectrum, it could be as simple as disconnecting and un-installing all of the modules to store them in a stack underneath the nearby deck for the winter. I'd like to think there might be a more "elegant" solution (and less labor intensive, and less wear and tear on the modules over the years). I wondered if there's a clever way to "drop" the modules to a near-vertical orientation so they could remain in place during the winter (some kind of hinge at the top and release at the bottom). I guess this might require individual rows of modules instead of one large array. (As a bonus, I'd like to keep about four mods (out of the 48) operational through the winter for battery maintenance and a few incidental loads. These could be vertically mounted on the south side of one of the buildings, above the typical snow drift level, for example.) Thanks in advance for any suggestions, ideas, things you've tried that haven't worked, etc!! Best, Blake -- Blake Gleason, PE | Employee Owner Director of Innovation and Technical Excellence O: 510-845-2997 x128 C: 510-867-5878 1035 Folger Ave. Berkeley, CA 94710 www.sunlightandpower.com<http://www.sunlightandpower.com> License #326203 _______________________________________________ List sponsored by Redwood Alliance Pay optional member dues here: http://re-wrenches.org List Address: RE-wrenches@lists.re-wrenches.org<mailto:RE-wrenches@lists.re-wrenches.org> Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org There are two list archives for searching. 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