I had 4x 405w panels installed on a tile roof (see below for what roof looks like).  The installer did not use tile hooks to attach the rails to the roof, but rather some kind of galvanized steel strap.  As far as I can see the strap goes under the tiles and is attached to the rails with screws.  The result of this is that the rail lies on the tile roof, but you can move the installation up and down because of the use of strapping instead of tile hooks.

Is this a common way to install the rails?

Edited April 14, 20206 yr by admiral

17 minutes ago, admiral said:

Is this a common way to install the rails?

Not that I know of. In fact, I'm about 90% sure this could never be okay, and here is why: The issue with PV modules is LIFT. If the wind blows under it at the right angle, it will attempt to lift it, turn it into a nice expensive kite. In this case, with wind at the right angle/strength, it is going to pick it up and put it down repeatedly. In time the straps will wear down (metal fatigue) or the screws might loosen, and when that happens it will lift up a PV module and put it down somewhere else... hopefully not through someone's living room window or the windscreen of his SUV.

Those straps are usually used for solar water heaters/tanks, and in that case it is allowed, because the weight of the water holds it down.

An interim solution might be to put a couple of sand bags over it to help hold it down...

@plonkster - that is what I thought as well.  Unfortunately only noticed this afterwards <sigh>

8 minutes ago, admiral said:

@plonkster - that is what I thought as well.  Unfortunately only noticed this afterwards <sigh>

Could you post some pictures? I'd love to see what kind of strap they used.

@plonkster this is just visible below the panel's edge

@plonkster The rails that were used:

26 minutes ago, admiral said:

The rails that were used:

Correct rails. and they come with roof hooks, less than R100 each. this is really sad. Make them return and fix it. 

1 minute ago, Jaco de Jongh said:

Correct rails. and they come with roof hooks, less than R100 each. this is really sad. Make them return and fix it. 

How much more work is it to install roof hooks compared to using the straps, out of curiosity?  Trying ot understand why you'd use the correct rail, but not the hooks.

4 minutes ago, admiral said:

How much more work is it to install roof hooks compared to using the straps, out of curiosity? 

Max 10 minutes per bracket.. if you slow... 1 Hour in total i would say. 

 

EDIT: I lie, they have already opened the roof for the strap and screwed it down. It would have taken exactly the same time as installing the strap. maybe even less, because it is quicker to connect the roof hook to the rail than connecting the strap to the rail. 

1 minute ago, Jaco de Jongh said:

Max 10 minutes per bracket.. if you slow... 1 Hour in total i would say. 

Including grinding the tile if you need to etc.?  Sorry, forgot to ask.

1 minute ago, admiral said:

Including grinding the tile if you need to etc.?  Sorry, forgot to ask.

My team of 2 guys take less than 2 hours to install up to 30+ brackets on a tiled roof. Including the layout. 

1 hour ago, admiral said:

@plonkster this is just visible below the panel's edge

That looks like roof bracing strap:

51 minutes ago, admiral said:

@plonkster The rails that were used:

Probably doesn't matter, it's probably just my mild OCD acting up, but take a file and take off that burr. I assume it was cut with an angle grinder. Nothing wrong with that, even though I prefer a mitre saw for the job 🙂

 

I have used that roof bracing strap to hold down my panels for many years, for tiled roofs. Never had a problem. Even used the straps on long pieces of wood as rails for a two year long installation at a place I rented for a while. Live in Centurion now and also never had wind issues I actually have 2×50watt panels just lying loose on the roof for a few years now. Never seem to get around to fitting them. No issues there either. My main panels (12 x 265 watt) were screwed to angle iron that was lying loose on my garage roof, no wind is gonna blow that away ever. But just to be certain I used polyurethane adhesive to stick the angle iron to my IBR roof sheets. Now it is stuck almost permanently and no holes in the roof sheets. 

Edited April 14, 20206 yr by Jaaks