Solar panel mounting (mechanical aspects)

[Julian_S]

Good evening everyone, I intend to DIY install a small PV system with simple grid tie inverter. Just a cheap as you can but everything done properly. I have an steel portal frame building that's 45' by 16', the roof is steel box section fixed to wooden purlins - entirely standard agricultural use. The building has a southerly facing aspect which is ideal, but unfortunately the roof has one foot of drop over its 16' width to the North. This was for simply for rain drainage and sadly it's in a bad direction for solar panel orientation. I've found some 435W monocrystaline 2180mm x 996mm x 40mm panels at a decent price. I'm guessing I need an arrangement to point them towards the south at about 30 degrees of inclination, rather like ground fixed panels? What do you think, some sort of aluminium bracketery, maybe stuff commercially available or will the first gale rip them all off? I'm not sure how mechanically strong the PV panels are.

Thanks, Julian

 

[binky]

Check out Schletter fix Z system, low profile tilt rails. You could also look at East West flat roof mounting systems. Given the roof is basically flat, you could just fit straight to the roof as you won't lose much performance, your biggest issue going forward will be keeping the panels clean

 

[Julian_S]

Thanks binky, your reply set me off on a Google search. Basically I think the solution is quite easy to get them pointing in a favourable direction and keeping them clean, which is something I hadn't considered. There's panel adjustable triangle support frames available - these are just three lengths of extruded ally angle full of drilled holes. So, if I purchase some ally angle I can make my own and custom build the length of the bottom to neatly bridge two purlins making fixing them very easy. I guess I'll stick in a cross brace at some point too, for wind. Fix onto them with the ''fast fix mounting rails'' with their bespoke mounting clamps and that's job done I think. My plan now is to fix 6 panels in 'landscape' mode, end to end to span the full length of the building. If all goes well and I upgrade in future I can simply add another row, spaced from the first row to stop them interfering with each other. Is this workable? Also, what do you think of these panels, the guys are not far from me and I think they seem good. Many thanks. https://www.ebay.co.uk/itm/325119545604

 

[revor]

Have a look at what Renusol have to offer you. They do a range of fittings for roof and ground I used them for my ground array. They did me a spec for my layout with part numbers and calculation for loading torque settings for bolts etc. Midsummer wholesale either have the bits or can get them for you. Have a shop around for panels think per watt what you intend buying seem a tad too much but it is over 12months since I bought my 335 W panels. There is an excellent guide by BRE National solar centre called Code of Practice for grid connected Solar PV systems. See if you can get your hands on a copy it will ensure you "do the job properly" as you want to do.

 

[binky]

Thanks binky, your reply set me off on a Google search. Basically I think the solution is quite easy to get them pointing in a favourable direction and keeping them clean, which is something I hadn't considered. There's panel adjustable triangle support frames available - these are just three lengths of extruded ally angle full of drilled holes. So, if I purchase some ally angle I can make my own and custom build the length of the bottom to neatly bridge two purlins making fixing them very easy. I guess I'll stick in a cross brace at some point too, for wind. Fix onto them with the ''fast fix mounting rails'' with their bespoke mounting clamps and that's job done I think. My plan now is to fix 6 panels in 'landscape' mode, end to end to span the full length of the building. If all goes well and I upgrade in future I can simply add another row, spaced from the first row to stop them interfering with each other. Is this workable? Also, what do you think of these panels, the guys are not far from me and I think they seem good. Many thanks. https://www.ebay.co.uk/itm/325119545604

JA panels are fine, I fit those quite often.

You are assuming you have to fix to the purlins, when you can get brackets that fit straight to the trapezoidal sheet and are very simple and easy to fit. (and cheap). Have a look at these 2 options.

I would be a little wary of raising the panels into being 'wind catchers' - that can go horribly wrong. Wind speeds in major storms is increasing in the UK, anything designed for solar should be able to withstand hurricane force winds. Ok we havn't had it that bad yet, but, things are getting worse. If you go for the triangular frame option you will get better performance, but see if you can buy something with a wind deflector that fits to the rear to make the installation more aerodynamic.

 

[binky]

Have a look at what Renusol have to offer you. They do a range of fittings for roof and ground I used them for my ground array. They did me a spec for my layout with part numbers and calculation for loading torque settings for bolts etc. Midsummer wholesale either have the bits or can get them for you. Have a shop around for panels think per watt what you intend buying seem a tad too much but it is over 12months since I bought my 335 W panels. There is an excellent guide by BRE National solar centre called Code of Practice for grid connected Solar PV systems. See if you can get your hands on a copy it will ensure you "do the job properly" as you want to do.

Renusol are good frames, I got stuck on Schletter many years ago and have used that for about 99% of my installations, so I have lots of spare bits, so stick with it. The other good framework is Redtip, my supplier doesn't stock that so I never use it.

 

[Julian_S]

Thanks chaps, I have looked at many commercial triangular support frames and decided that they are nothing more than three lengths of aluminium angle with lots of superfluous holes in the things. I live in a windy spot up a hill so I kind of decided that any fixings needed to go into the purlins for peace of mind, accordingly the frames were either too long (yes, I know that doesn't matter) or too short. So I thought what the heck, and priced some 5 metre lengths of angle (of bigger dimensions) alloy from the local stockist and decided I was quids in. I'll cut them to size and so make them absolutely bespoke for the job, some stainless bolts, and some long tech screws for the fixing to the roof. As the panels will now point in a southerly direction and our gales come from the south west I think the wind factor is taken care of, but a wind deflector will be an easy job the fabricate. Just need to decide upon a good panel supplier now and decent panels at a sensible price, I wonder if any take cash. I'll look out for that code of practice. I've found a good ebay supplier who seems to specialise in used inverters, I'm going to take a chance on a used one as there's every chance it will be chucked out in a year or so when I decide I want more cells and/or batteries.

 

[binky]

Unistrut may save you some work

 

[stuboy]

I also live in a windy spot and am about to do a very similar install, using 2" ali box, drop me a pm and we can compare notes. I might have a good panel supplier 4 u too ;-)
Cheers
Stuart