The first direct-attach PVKIT was released almost a decade ago, disrupting the industry and providing a simple, cost-effective way to mount solar to both standing seam and exposed fastener metal roofing without using rails. This innovation drastically reduced the material needed to install solar. When you think about it, with a metal roof, the standing seam or the ribs of the roof are your rails.
Upon reading the Solar Power World article Metal Roofs are No Problem for Solar Installations, my reaction was, "Well, I suppose that is true—if (and only if) it is done 'the right way.'" There are so many materials, profiles, gauges, metallurgies and corrosion behaviors to consider; not to mention effective waterproofing methods, sealant chemistries, thermal cycling characteristics, weathering behaviors, strength of materials, structural engineering principals and relevant test methods. It is anything but a simple science!