MCI rooftop layout

[dtcerrato]

Seems like a whole lot of work as we just mounted our panels individually but our system is a small supplemental one @ 100w/panel x 5. I know you guys are running bigger systems with much larger panels. We're delighted not to have to worry about keeping batteries charged while boon docking...

[luvrbus]

It would be easy to do that run in several sections with 1/2 inch gaps at the section ends..>>>Dan

Buses move around a lot that is why they have lap joints and use a 1/2 dozen different type rivets

[Jim Blackwood]

You might be able to find or have formed up some telescoping sections to slide inside your unistrut. That way the sections could shrink and grow with heat and not buckle anything. Bolt one end and let the other float. Those plates might work but I'd do two things. Make sure there is a good durable sealant between the plate and the roof, and also countersink the bottom of the holes so it isn't sitting on the flange of the rivnut. No wait, you said you were putting the rivnut in from the top of the plate I think. In which case I think it might be good to put a little sealant on the rivnut before it goes in the hole also, and then use those sealing washers. Maybe even some sealant on the threads.

Also, use rivenuts with a generous flange and get the most heavy duty rivnut tool you can manage. Probably something with long double handles or pneumatic. And then learn to use them without applying so much force you break things. Aren't Huck fasteners available in a rivnut style? If they are that would probably be your best bet. The biggest challenge with rivnuts is getting them secure without damage but tight enough to not slip. And sometimes the screw or bolt does not go in as easily as the mandrel comes out and spins the rivnut. In some cases it's necessary to chase the threads with a tap and use anti-seize to get a good solid connection. So everything that can be done to insure the rivenut is well seated and the fastener screws in with the fingers should be done. Of course if it fails you can always drill it out and start over but if it wants to spin you might end up doing that with a die grinder and trying not to nick the sheet metal. Which is kind of a pain.

Jim

[dtcerrato]

We've installed lots or various size rivnuts without ever using the dedicated tool. We use a small flat bar that come with some rivnuts and insert the proper size bolt through it - tighten the bolt down with a battery impact then remove the bolt to take away the flat bar tool & move on. It's worked great without issue FWIW

[windtrader]

Thanks for all the tips. This group is awesome, lots of knowledge and willing to share.


I'm going to make the lengths of struts 6', the length of two panels on the short side. That will eliminate any expansion issues. Next aluminum flat bar to raise the struts off the roof, allowing for air and water flow. Three sets of rivnuts mounted through a washer, strut, riser plate, roof. Several ways to seal hole, tbd. Then bracket to secure PV panel to unistrut. Easy to install and strong enough. lol

[chessie4905]

use aluminum unistruts to equalize expansion.

[windtrader]

how much of an issue using steel channel on 5 foot length? still need aluminum? getting quote now but i suspect more money.

[chessie4905]

personally, I would use aluminum with aluminum roof panels for comparable expansion plus no rust issues. Small increase in cost compared to cost of rest of system and better for heat dissipation from panels.