Stud welding

[epretot]

Curious what everyone's thought are on stud welding to the bus roof.

Most demonstrations I have watched use thin guage sheet metal.

Thinking of mounting solar with super struts or unistruts. Wondering if this is an alternative to penetrating the roof panels with nutserts, rivnuts, etc.

I have even seen the stud deliberately bent over to show strength of the weld...

[freds]

Interesting idea, would go with more studs then you think you need.

[epretot]

My welder friend gave me a fast no on this idea

Says it's not strong enough.

[Dave5Cs]

We used self tapping 3/8" screws with 3M double sided tape under the feet before I screwed them down. 4 years and no problems. 1500 watt panels 6, 250 watts house panels

[Busted Knuckle]

My welder friend gave me a fast no on this idea

Says it's not strong enough.

Trust him and follow his advice!
  BK 

[windtrader]

Speaking from personal experience, make sure it holds the panels. Through holes are easily sealed and the strongest way. Rvinuts are strong. The strongest way is having access from the inside. That way you can put whatever for reinforcement.

[Iceni John]

My eight 255W panels are hinged from a central walkway that I built between the two roof hatches:  this walkway is through-bolted at every roof rib with a total of thirty-six 3/8" stainless socket-head bolts from underneath.   The outer edges of the panels are supported by lift struts that are similarly attached with thirty-six 5/16" bolts.   It's not going anywhere!   I sealed all of them with EPDM washers against the roof, squeezed down by stainless washers above them, and in the heavy winter rains here not a drop of water came in.

I would NOT recommend attaching something as heavy and with such a high windload by the roof skin alone.   It's not intended for that type of load.   Imagine if a panel attached that way came off while driving and hit a car behind  -  what would the insurance company and lawyers and judge say about that?

John

[windtrader]

I would NOT recommend attaching something as heavy and with such a high windload by the roof skin alone.   It's not intended for that type of load.   Imagine if a panel attached that way came off while driving and hit a car behind  -  what would the insurance company and lawyers and judge say about that?

John

John is being kind. I'm sure he read my encounter with solar panel mounts surfaced glued. In my case, no insurance company or worse. Got very lucky as multiple CHP across jurisdictions got involved. Don't underestimate the force of the wind at highway speed and a stiff side or headwind.

[Dave5Cs]

I have a second rood and they ae screwed into the rafter between the two and the 3M tape holds well if you sand to clean metal.

[Jim Blackwood]

Maybe you could use toggle bolts. 
Seriously though rivnuts are pretty good and you can get blind ones if you look hard enough. That and a little "Right Stuff" sealant under the head should make it water tight. Go for a large shoulder on the rivnuts and get a double handed or hydraulic or pneumatic nutsetter and use one of the larger sizes so it has more tin to grab onto and then use more of them than you think you need. Check them after your first few trips to make sure they aren't moving any at all. Do a test crimp on a similar thickness of similar metal and try to spin it and pull it out.

Jim

[chessie4905]

I would think Riv nuts too, but the constant buffeting from the wind while traveling may cause metal fatigue and cracking which is more common on aluminum. Lot of surface area on a panel to cause this. Will need to be checked frequently, especially on large accumulation of miles. Definitely use antiseize on the bolt threads. Doesn't  take much corrosion to cause a rivnut to spin in the hole.

[dtcerrato]

We used self tapping stainless steel screws and neoprene washers. The front most panel is in a structural member the rest are just the roof skin. About a year now and no issues.

[epretot]

The only negative I have read about penetrating trough a framing member is the possibility of messing up the seal.

My ceilings is open and will remain so for a while. I could install some bracing away from the seams.

Perhaps hinging them to the gutters.

It would double as an awning...

[Iceni John]

It's quite likely that solar panels could be securely attached to the outer roof skin, but the big question is how well is the skin itself attached to the roof ribs?   It matters not one jot if you use PlusNuts or rivnuts or whatever to attach to the skin, but if the skin is only attached with wimpy little fastenings to the ribs, then the weakest link in the chain still remains.   Besides, how strong is the skin itself?   This is one area where you need to be very cautious and conservative, and take heed from the Victorian engineers who overbuilt everything*: their constructions are still standing strong two centuries later.

Isambard Kingdom John

* OK, the first Tay Bridge was a complete cock-up, but the next one is still doing just fine.

[chessie4905]

Didn't know that bridge was aluminum.