I'm finalizing my rack for solar panels on my 7'x14' V-nose cargo trailer. The trailer's roof frame is curved (roughly 1" taller in the middle than the sides). The steel beams are roughly 16" on center. I am installing three 330W panels (Silfab SIL-300BL) that are 66.9" x 39.4" and 41 pounds each. The three panels just fit (1" to spare) between two roof fans.
I've modeled most of the trailer frame and my rack plan using SketchUp. The attached screenshots are from the model.
The first picture shows a view from above. The back of the trailer is to the left. The "floating" fan to the right is in the V-nose which isn't shown in the model. The panels are shifted to line up with the left side of the trailer because the right edge of the roof will be used for something else.
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As you can see the rack is comprised of four rails made from 1.5" aluminum extrusion. The panels will be secured at the 4 provided mounting holes in their frames. I'm going to make custom feet for the rails using 2" leg, 1/4" thick aluminum angle. This setup lets me deal with the roof curvature and the fact that the roof beams don't line up with any of the mounting holes in the panels. I'm using four shorter rails instead of two full-length rails to save a bit of weight (and a few $$). This setup also allows the panels to be roughly 3.5" - 4" off of the roof for good ventilation as recommended by the manufacturer.
The second picture is a view from the right side of the trailer looking toward the left side.
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The third picture is a view from the front looking to the rear.
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The fourth picture is a close-up of one of the rails and the custom feet.
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1. My main question is this a viable, safe design? In other words, is there any risk of this ripping off of the trailer while driving down the highway at 70mph? Each panel will be mounted to the rails with four 1/4" stainless steel bolts using the panel's designated mounting holes. Each custom foot is attached to the rail with two 1/4" screws. The two halves of each custom foot are held together with two 1/4" bolts. And each foot will be attached to the roof beam using 1/4" bolts screwed into drilled and tapped holes in the beam. Each rail will be secured with three feet on three beams.
2. While the panels will be mounted at their designed mounting spots, how well will the panels survive the rigors of being on the roof of a moving vehicle over time? The panel frames are sufficiently secured to the rails but I'm worried about those 41lb panels bouncing and vibrating with no support to the glass itself except around their perimeter.
3. Grounding - My thought is that I don't need any grounding with this setup since the metal solar panel frames are bolted to metal rails which are bolted to metal feet that are bolted into the steel beams of the trailer. The rails are anodized so I'll use exterior tooth lock washers in the mix to help ensure the anodizing is broken at the connection points. Is this valid logic or should I still attach grounding wires to each panel and each rail and connect those wires directly to the steel roof beams?
Any feedback is appreciated. Thanks.
