Panel mounting system for steel sheet roof?

[Jinx]

The 'stitching' screws are only holding the edge of the sheet down so no great strain. The solar panels could get a lot of wind loading and I would be very nervous if they were attached to just to a single thickness of the steel sheet.

Yes it does seem a lot to ask of a single skin of .7mm steel.

I did my latest solar addition using 2" x 2" timbers. Heavily treated, laid out timbers, marked and drilled the peak flats of the corrugated sheeting and fixed from below with 2" screws and M5 s/s flat washers. Each screw spot had a blob of roof sealer. each rail held in place with 31 screws. It is going nowhere and doesn't leak.

https://www.screwfix.com/p/geocel-trade ... 10ml/72630

This might be the answer, through the peak but into a timber below to gain fixing and spread the load, seems like a good plan

[Joeboy]

The 'stitching' screws are only holding the edge of the sheet down so no great strain. The solar panels could get a lot of wind loading and I would be very nervous if they were attached to just to a single thickness of the steel sheet.

Yes it does seem a lot to ask of a single skin of .7mm steel.

I did my latest solar addition using 2" x 2" timbers. Heavily treated, laid out timbers, marked and drilled the peak flats of the corrugated sheeting and fixed from below with 2" screws and M5 s/s flat washers. Each screw spot had a blob of roof sealer. each rail held in place with 31 screws. It is going nowhere and doesn't leak.

https://www.screwfix.com/p/geocel-trade ... 10ml/72630

This might be the answer, through the peak but into a timber below to gain fixing and spread the load, seems like a good plan

No worries, glad to help. Our corrugated roof has been very well fixed down yet adding the upper timbers and fixing again I could feel the roof tighten up more. Add a layer of panels (in effect a 4 layer X lam) and its a solid structure. Best of fortune in the project.

[Gareth J]

I did an array on a trapezoidal sheet roof with these (well, a previous model) 5-10 years ago.

K2 Mini Rails with CT1?

But on old, cheap, painted, thin tin, not the heavier stuff you have. No sealant required. They've weather all storms, including several that have caused other roof damage to skylights and cement fibre sheets.

The only place it's a bit less than satisfactory is where I had to fill in a skylight, so the roof doesn't have a full length of tin eaves yo ridge. There's a bit of sag there. Rails let you even out roof variability.

I was so pleased with the installation, and how easy it was, I did another on a new roof put up with PV in mind. Used small wriggly tin from cladco and a ridge based version of the K2 brackets.

Not only are direct to roof mini brackets cheap, because they're so material efficient, they put panels closer to the roof. Too tight for anything bigger than a sparrow to nest under. And are quick to install.

[pudding]

2 of my arrays are on wiggly tin roofs, both cladco profiles. Both attached with mini rails, which have rubber bases which seal as they're screwed and compressed on, same way as the fixing screws do with their rubber washers. No leaks over the years and all solid, despite being screwed on one roof into just 0.5mm sheets. (so far!) Very easy to install. Can find close up pics if wanted?

[Jinx]

Thanks chaps, my rails arrived and I have dummied one up on a scrap piece of the roof leftovers.

Here’s a close up, looks like it will do the job fine. Even on the edge of this piece of scrap it is very secure and I can put a fair amount of pressure on it no problem.