I tried a rail-less system on a roof mount once, but never again. It worked roughly as advertised, but the problem was aesthetic. It was a bear trying to get the modules parallel and flat. Too many degrees of freedom and no roof is as flat as you’d wish. With rails at least the modules are lined up in one plane.
I’ve seen a few no rail installations on raised seam roofing and noticed the “diving board” problem. The width of the modules never corresponds exactly with the seam spacing. Some modules end up hanging out over the last mounting points a bit too much. Also, in terms of safety, rails spread out the load over multiple mounting points, so no one point takes an extreme load and the failure of any one point isn’t immediately fatal. Rails, yes. Hilton Dier III Renewable Energy Design Missisquoi River Hydro LLC _______________________________________________ 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
