Author Topic: DIY Panel mounting on tin roof.  (Read 2362 times)

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george65

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DIY Panel mounting on tin roof.
« on: August 04, 2017, 06:29:01 AM »

I'm interested if anyone has any DIY Solar Panel tin roof mounting Suggestions?

Here solar mountings are unjustifiably expensive and very difficult to get used. I have taken my panels off the awning where I had them mounted hereto take to the new place. I want to put them on the shed and then the pergola roof. The Shed is 9m long and has 2 levels ( barn type Config) on the roof. I believe the roof is 11o angle and I need 33o.

I have looked at the data from the local airport and while every month has gusts of between 35-50 knots, the good news it the stronger guts come from mainly the north to NE  so are blowing onto the panels rather than under them ( Southern Hemisphere). The roof has plenty of tek screws holding down te sheeting so plenty of tie down points.

Any DIY suggestions appreciated.

BruceDownunder

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Re: DIY Panel mounting on tin roof.
« Reply #1 on: August 04, 2017, 09:16:53 PM »
Yes, the al mounting rails are so expensive,guess it,s a special extrusion ,used by only solar installers.

I looked at the purlin type "tophat" extrusion.  I think it,s very strong ,you can order it in different sizes and thickness.  Mine is 7.2 mtrs long in one length-thats another cost, getting it delivered.too long for your car/trailer.

 Then you have to be fairly accurate in your location of fixing points -you don,t want holes drilled all over the place.  thats where the real stuff is best,I guess.

 when you have tradies wanting $400-500 per day wages ,thats why they use the quick fixing stuff.

 Bruce

frackers

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Re: DIY Panel mounting on tin roof.
« Reply #2 on: August 05, 2017, 05:13:33 AM »
I used 40x40x2mm wall galv steel box for the frames for my 24 panels on the shed. Can't remember how much I used, must have been approaching 200m of it.

We generally have a shed face north here to get the sun (and avoid the rain which is mostly from the south) but slope to the back so the angle of the roof is totally the wrong way. I put 3 holes in the uprights so I can adjust over the course of a year according to http://www.solarpaneltilt.com/

Probably over engineered but it has survived hurricane force winds (gusting over 150km/hr) ;)

http://gilks.ath.cx/gallery3/Solar
Robin Down Under (Or Are You Up Over)

bigrockcandymountain

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Re: DIY Panel mounting on tin roof.
« Reply #3 on: August 05, 2017, 07:27:44 AM »
I built a tilt up, two position set out of steel for mine. 12 250w panels.  Aluminum would be better for corrosion but more expensive. 

It has feet that are 6" long of 2" wide strap.  1/8" thick.  Two holes top and bottom with a 3/8" bolt in each.  I used scraps of strap for the washers on the backside.  There are 24 of these feet on the rack.  That's 48 bolts to pull out.  I did z shaped clips around the perimeter to hold the panels to the frame.  Just bent 1 1/2" wide strap in the vise with a big hammer. 

If you want I can go up and take pictures.  We get similar winds to you.  Maybe a little stronger.  They have held for a year. 

The gaskets under the feet are inner tube rubber. 

george65

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Re: DIY Panel mounting on tin roof.
« Reply #4 on: August 06, 2017, 06:26:30 AM »

Thanks For the suggestions!
Very helpful and along the lines of what I was thinking of.  I had in mind to use 25MM tube and screw it direct to the panels. Wasn't sure if that was dodgy but seems not.  I was also thinking of adjustable. Might be the one thing that has a better trade off done as Frackers has shown than just adding more panels.

Just to clarify, if my " ideal" angle for my location ( Sydney) is 34o, the winter adjustment would be about 50o and the summer tilt around 20o?

Mary B

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Re: DIY Panel mounting on tin roof.
« Reply #5 on: August 06, 2017, 05:08:22 PM »
Most lumber yards carry this https://www.menards.com/main/electrical/strut-support-systems/unistrut-strut-channel/p-1444424000448-c-12477.htm?tid=9155822755740750234&ipos=2&bargainStoreId=3270 along with the spring nuts that go in the channel. I used it to mount my panels on the ground frame and it has survived 95mph winds

SparWeb

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Re: DIY Panel mounting on tin roof.
« Reply #6 on: August 07, 2017, 02:17:15 AM »
I used Unistrut too.
The website has some contacts down under.
http://www.unistrut.com.au/index.php?P=contact_locate_au

Bolting the aluminum frames of the panels directly to the steel rack or steel roof tends to create a corrosive current when it's wet.
See if you can find a way to put some isolation between them.
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

Bruce S

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Re: DIY Panel mounting on tin roof.
« Reply #7 on: August 07, 2017, 11:40:42 AM »
I went with "L" iron brackets painted with oil-based paint. Iron was free.
 I used pieces of an old inflatable kiddie pool to put between Aluminum and Iron  contact points, and stainless steel bolts/washers.

A kind word often goes unsaid BUT never goes unheard

Mary B

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Re: DIY Panel mounting on tin roof.
« Reply #8 on: August 07, 2017, 04:18:25 PM »
I made Z shaped standoff brackets and used anti oxidant electrical paste under each contact point. Once a year I loosen them and use a q tip to apply more paste. Also lets me check connections and make sure nothing is broken or bent...

george65

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Re: DIY Panel mounting on tin roof.
« Reply #9 on: August 07, 2017, 05:21:44 PM »
I thought of the Unistrut but last time I wanted some , it wasn't cheap.
That said, the links show the head office is 10Km from where I am so very convenient. I'll work out what size I need and give them a call.
Last install was soo much easier. Just leaned them on the roof over the guttering and screwed the panels directly through  the awning below. Gave nearly ideal tilt.

I was a bit worried about how this would hold up but we had some of the strongest winds in 25 years here and they didn't move.

I checked the roof yesterday and it's only 7o tilt, fortunately in the right direction. I need 34 but I'll make the frame 30 so it's easy to build and maybe the extra tilt will give me a bonus 1 kw/ yr over winter or something.  :0)

I'll have to look for some Z brackets. I'm more concerned about securing the things at the bottom than the top.  I won't have much room to screw them at the bottom but plenty of clearance at the top.

I have done a bit of reading up on galvanic corrosion. I don't think it's going to be practical for me to isolate the panels from the frame. I could with the frame and the frame of the panels themselves, but with the screws, bolts, don't think I would do much good and in fact may concentrate the effect to a small area.

From what I'm reading, Aluminum and gal steel in a rural environment should hold up well. They are next to each other on the galvanic table so should have the minimum reaction. I don't think I can isolate them too well but I'm thinking a good coat of grease on the mating surfaces and on the fastenings may work to help keep the moisture out which would prevent the effect.
"Wet" time should be minimal. The heat radiated from the panels should dispel any moisture beyond humidity pretty readily.
I'll go with that and see how it pans out. Chances are I'll change things around a bit later on anyway.

I only realised the difference in size between the 260 and 190 panels I have when I took them down and stacked them together so the unistrut being able to be built adjustable would be an advantage.

frackers

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Re: DIY Panel mounting on tin roof.
« Reply #10 on: August 07, 2017, 08:28:54 PM »
To meet electrical compliance, I had to ground the frames of all the panels and all the support frames with 6sqmm cable with star washer fixings to pierce the oxide layer on both the ali and the galv.

4 years and 28 megawatts on and I have no corrosion at all.

My fixings are 150x8mm tek screws (6 per frame) through the cross pieces (see photos in link above) into the purlins and 100x8mm tek screws (4 per frame) through the ends of the frames into the rafters. In all but 1 case I managed to get the screws through the top of a corrugation on the roof. The galv frames just sit on the iron  (Coloursteel) of the roof and spread the load (which with 24 panels is over a tonne).

The panels are all fixed with 8mm stainless bolts to the galv frame.

Not cheap using the square tube but I don't loose any sleep if it blows ;)
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MattM

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Re: DIY Panel mounting on tin roof.
« Reply #11 on: August 10, 2017, 01:09:05 PM »
Your wind protection begins on the roof perimeter. Keep wind from undermining both the roof and any panels.

frackers

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Re: DIY Panel mounting on tin roof.
« Reply #12 on: August 10, 2017, 06:32:38 PM »
Your wind protection begins on the roof perimeter. Keep wind from undermining both the roof and any panels.
That's certainly true for a house with a pitched roof but for a shed (sorry - rest of the world calls them barns) with a pitch of 5 degrees away from the equator its not possible to keep solar panels flat so they DO end up with a bit of windage.
Robin Down Under (Or Are You Up Over)

MattM

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Re: DIY Panel mounting on tin roof.
« Reply #13 on: August 10, 2017, 10:48:23 PM »
A skirt equivalent to an 'aerodynamics package' on a sportscar would be simple enough to prevent undermining.  Something simple that redirects air from shingle level to up and over the sides, and which minimizes air under it.

george65

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Re: DIY Panel mounting on tin roof.
« Reply #14 on: August 12, 2017, 08:54:08 AM »
I thought of the wind getting under the panels and the sail effect.
I looked up the prevailing wind direction and while it shifts a bit, the strongest winds could come from the north east.  The Shed is slightly orientated that way so the majority of the air would be Face on so pushing down, not lifting up.

I intend to bolt/ screw the frames into the existing holes in the metal and apply a dob of silicone for good measure for leakage protection.  A friend is a sheetmetal worker that does aircon duct so maybe he could make something up like a skirt IF i'd need it.  Max wind gusts are quite even in the 50 kmh range which I don't think is that strong. From what I can find, seems that's as strong as they ever get but I do remember my uncle that lived close by on the top of the hill about 20 years ago loosing his workshop roof. He built the place. That roof would have been over done as was everything else he ever built.

I guess where I am would be a lot more protected being on the lower side of a hill with other buildings and trees around. 

I did think of enclosing the panels on the outdoor area roof and putting a fan in to circulate the air and divert the warm air through a filter and into the home.  Unfortunately, the pitch of that roof is perfect so no gap or tilt required to give any space.