Mounting points on roof?

Doing a bit of roof cleaning with a view to fitting a bigger solar panel on my Nuevo. I've always wondered what the six mounting points fitted with domed nuts are for. The studs are only 6mm diameter so I can't see them being for any kind of roof bars, the various skylights are in the way for that anyway.
Al[You must be registered and logged in to see this link.]

Me too, Al.

from memoryI think they were for roof bars which AS supplied, some Nuevo's had a ladder on the back to access, you may notice a recess in the skirt as a step

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If they were using acorn nuts, couple of, perhaps, picky points...
Why a stack of washers under them, just cut the stud to the correct length?
Why use non SS washers?
Why not just one SS penny washer to spread the load better and not rust as a bonus?

Sorry, have fussy head on today having found a failed pop rivet on my water drain clip!!!

Caslon wrote:from memoryI think they were for roof bars which AS supplied, some Nuevo's had a ladder on the back to access, you may notice a recess in the skirt as a step

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Damn! I wondered what the recess was for    good to know 

I knew the recess was for use with a ladder, but the six studs on the roof seem a bit puny for mounting anything on. 
Al.

And I have the studs but no recess !

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I often carry a Canadian canoe on the rack on top of my Nuevo.      Never had a problem.