Roof solar panels direct fit or custom rail

[Plant]

I have four panels and am debating either directly mounting them with the method below or using some type of custom rails.  My current preference is directly mounting.  

Before I commit, any feedback by those of you that have used this method would be greatly appreciated!  If you have done this, have they stayed secure? Did you find that the roof metal is strong enough?  My van is a Ford E350.

How I would do it:
The panels would placed directly on roof with Renogy Z brackets using an eight inch thickness of rubber cut the size of the Z bracket between it and the the roof.  The self taping bolts that come with the Z brackets would be sunk into rubber/brass compression nuts ensuring a secure attachment.  I would use putty tape  and lap sealant covering the brackets up top for a good seal.

Compression nuts:  https://www.amazon.com/gp/product/B015EW0314/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1 

The attached picture shows a trial fit. They line up well to the ribs in the roof and also miss the cross members.

 

[highdesertranger]

I don't like those rubber expansion nuts you linked to. I found they leak and they seize up the hardware and require grinding to remove. the link is for 10-32 machine screws not self tapping bolts. highdesertranger

 

[Plant]

The Z bracket kits from Renogy have the screws. The linked nuts are threaded for the ones in the kit.

Do you think a better way of doing it would be to drill holes and use a regular bolt, washer, lock washer, nut combination? Perhaps with the bolt facing up through the roof?

Any concerns with the weight of the panels directly on the sheet metal roof?

 

[ssminnow]

How long are the panels and how wide is the roof?

 

[B and C]

Looks and sounds like you are chomping at the bit to get this done. Mine are flexible panels held on with industrial strength velcro as my van has a fiberglass top.

IIWM, I would put butyl tape down under the Z brackets instead of the rubber where they attach to the roof. It is sticky on both sides and provides a good weather seal. It can also be scraped off if needed. Drill the right size pilot hole (smaller than the screw) for the screws and screw them down but don't strip them. If you do you can always put the next size larger screw in. Use Dicor self leveling sealant around the edges of the brackets and around the screw heads. RV's use butyl tape and Dicor extensively. We used this method on a friends trailer and it works well.

I would not use bolts and nuts at all as it would take two people to install or remove. If you ever finish the inside and want to remove a bracket for any reason, it would be a nightmare.

Your roof is plenty strong to hold the panels.

 

[Plant]

How long are the panels and how wide is the roof?

I don't have the exact measurements handy, but I recall the panels placed across the roof do fit with a few inches to spare when I trial fit them that way.

 

[Plant]

Looks and sounds like you are chomping at the bit to get this done.  Mine are flexible panels held on with industrial strength velcro as my van has a fiberglass top.

IIWM, I would put butyl tape down under the Z brackets instead of the rubber where they attach to the roof.  It is sticky on both sides and provides a good weather seal.  It can also be scraped off if needed.  Drill the right size pilot hole (smaller than the screw) for the screws and screw them down but don't strip them.  If you do you can always put the next size larger screw in.  Use Dicor self leveling sealant around the edges of the brackets and around the screw heads.  RV's use butyl tape and Dicor extensively.  We used this method on a friends trailer and it works well.

I would not use bolts and nuts at all as it would take two people to install or remove.  If you ever finish the inside and want to remove a bracket for any reason, it would be a nightmare.

Your roof is plenty strong to hold the panels.

Yeah it would be nice to be ready for a run, but it will take as long as it takes and I'm satisfied with my progress. 

I think we talking about the same sealant products.  I was referring to the the Dicor as lap sealant, and butyl tape as putty tape.  I'm new to these products so may have been referring to them incorrectly.

The bracket surface facing the roof are parallel to the panels and the roof seating surface is slightly concave, so they don't mate against each other flush.  My thought was that the ~1/8 inch rubber would fill the gap and cause a better seal.  I could be wrong on this, as you mentioned perhaps I should just use the butyl tape to fill the gap.

 

[ssminnow]

I think I would try to mount some rails along the gutters of the roof somehow. Then I would do my mounting off them with cross pieces, that way you wouldn't have to put any holes in the roof. You might even have room for a couple more panels or something else that could be mounted with that system.
It just seems like there is some roof space being wasted doing it like the picture shows. With a rack system like that you can mount anything any size up there within the parameters of the roof size and nothing will be mounted on the roof itself. Those are some hefty panels ya got there, they look like about 300 watt"s a piece!
Nice!
Good Luck!!

 

[bullfrog]

If I'm not mistaken the bolts and nuts in the kit are for mounting the Z brackets to the panel. Mine came with lock washers and nuts which I replaced with stainless locking nuts. No holes in the roof guantees no leaks. Cooler panels preform better and more clearance means less heat below the panel and inside the van in warmer temps. Since these vans are used comercially several well thought out racks are available to buy or copy. If you change vehicles you can take the rack off without having to fix the roof. Tilting panels will be much easier built off a rack if you find cloudy winter days or more appliances require more watts without adding panels possibly. In my opinon the panel frame could use some extra support by bolting it directly to a rack in several points rather than using the Z brackets and four 10/32 bolts as it flexed pretty easily when I mounted mine temporarily. I'm still thinking though.

 

[highdesertranger]

I would install a gutter rack and install the panels on that. that way the only hole in the roof is for the wire feed. highdesertranger

 

[Plant]

My initial thinking was that the lower profile of the panels directly mounted to the roof sheet metal would be desirable.  Better cooling than flexible, and not as in your face apparent that the roof is full of panels.  But I am having reservations, and thats probably why I posted.

You guys do have my thoughts evolving on this, and I think I'm going to start looking at the roof racks available for the van.  I recall a video by Bob installing a roof rack, I'll watch that again. It does seem there are some advantages as mentioned by you guys.

Thanks for helping me figure this out.

The panel size was mentioned a couple of times.  They are 100 watt Renogy panels.  I think that one picture makes them appear large.