I tend to agree about the clamps, and in a case like this where there is little risk of an expensive mistake with a voided warranty, I would actually drill holes in the frame and use bottom clamps in addition to top clamping.
Jason Szumlanski Fafco Solar From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of William Miller Sent: Tuesday, March 22, 2011 5:48 PM To: RE-wrenches Subject: [RE-wrenches] Rail concerns (was: Top of POST mount) Friends: When installing modules on extruded rail systems, I worry that any vibration or motion could loosen top-down clamps. Unlike bottom-up systems that install with tried-and-true bolts and lock washers through captive holes, clamp systems seem less "positive" in holding capability. If one rail in the proposed design moves in relation to the other, the clamps could loosen and the modules could eventually slide right off the rail. It appears that wind turbulence could rock the modules in the proposed design, there is a lot of leverage for that. This might loosen clamps. I hesitate to design my own racking. Small business management is all about controlling risk. I do not want to be responsible for damaged modules if my design fails. At least one local AHJ forbids home-brew racks for a permitted system. I'm not sure I support that restrictive approach. I might suggest allowing them for owner-builder systems where the home owner assumes the liability. For myself, the remaining tasks associated with installing a system properly have enough pitfalls without me playing structural engineer. And lastly, it is my understanding that Solar World had temporarily abandoned mounting holes in the back rails of their new "Plus" modules (my quotes) and even abandoned the flanges altogether. According to what I heard, industry pressure forced them to add them back in, but as an option. This is third-hand knowledge, but I do know that removing the option to mount panels with through bolts would be a big mistake. William Miller Here is my "cobulated" idea, admittedly done this way to take advantage of parts in stock: http://www.fafcosolar.com/download/402/Cobulate.pdf
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