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Type of roofing recommended for solar panel installation


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Hi there
Thanks for a great forum guys
Are there any recommendations for a type of roof for a solar installation in Gauteng for a home. 

Eg. 20degree metal? vs standard roof tiles vs? what options are out there?

Considerations:

  • What do installers prefer?
  • There must be no birds being able to nest beneath it.
  • Secured well against wind and theft
  • Great thermal and sound insulation for the bedrooms beneath
  • Easy maintenance for washing of panels.
  • How are mounts done on metal vs tiled roofs? Drill through tiles etc? Doesn't this cause waterproofing issues?

I'm busy with an architect and have the opportunity to do this correctly. Suggestions?
Thanks.

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1 hour ago, Keill said:

Are there any recommendations for a type of roof for a solar installation in Gauteng for a home. 

Kliplock works best for me, the clamps are non intrusive and  no compromise made in regards to the integrity of the roof. 

My second option would be normal "Clay" Tiles. They slide open, you fasten the bracket and slide them close again. Very little changes for leaks.

Corrugated and IBR also works fine, but you have to drill screws through them that might lead to leaks ext if not installed correctly. 

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3 hours ago, Keill said:

Hi there
Thanks for a great forum guys
Are there any recommendations for a type of roof for a solar installation in Gauteng for a home. 

Eg. 20degree metal? vs standard roof tiles vs? what options are out there?

Considerations:

  • What do installers prefer?
  • There must be no birds being able to nest beneath it.
  • Secured well against wind and theft
  • Great thermal and sound insulation for the bedrooms beneath
  • Easy maintenance for washing of panels.
  • How are mounts done on metal vs tiled roofs? Drill through tiles etc? Doesn't this cause waterproofing issues?

I'm busy with an architect and have the opportunity to do this correctly. Suggestions?
Thanks.

North Facing roof between 25 and 30 degrees most panels are 1000mm W x 2000mm H or less IBR structures are the cheapest and easiest to install using good quality structures and a good installer means no leaks tile roof requires tile brackets and can get expensive its also more labour intensive to install also risk of breaking tiles is high.

Using decent quality roof structures will ensure propper fitting and correct wind load ratings they are normally pre approved.

Typically birds won't nest under the  panels the temperature under the panels get too high most quality panels just require water to clean them and there are special coatings you can apply to the panels that reduces dust and dirt from sticking to the panels.

My recommendation would be to stick to known name brands when it comes to solar panels and structures like Canadian Solar and Renusol.

Also later if you have name brand panels and one breaks you can easily find a replacement.. my 2 cents

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There is a backstory, but let's start here:

I said their perfectly angled frames allowed them 22 panels on their roof, if they were fitted flush I'd get 60 odd in the same space, and it would look better.

There existing frames didn't move because of gravity, they were actually free standing, self-welded monstrosities that took 4 men to lift.

Drill holes they'll be leaks they said, wouldn't hear anything different.

I was told I had to find a way of installing panels without putting any holes in their IBR roof.

Well, I am going tell you how I did and how intend to do it again, because it works a treat.

Double -sided sticky tape.

Don't laugh, hear me out.

On an IBR roof I sticky tape unitstruts every so often down the raised bit, down the slope of the roof.

(Galvo clean the unistrut first).

Don't ask me measurements, ( about a metre-ish) in reality it was every so many bumps, not scientific.

Then I create a horizontal lattice of unitstruts bolted to the vertical  unistruts.

The horizontals are at the correct fixing for vertical panels. The horizontals are moveable, unistrut has these nut+spring things.

This gives the panels two unistruts profile thicknesses over the IBR mounds and probably the equivalent of three over the IBR channels. ( so probably about 100mm gap average).

Unistrut also makes a clamp that go in between panels, it is about a quarter of the price of the "solar" clamps.

And its very quick to install, (make your frame earth loops on the ground and fit to one side of each panel.)

I had 4 panels up for a year trialing this method. (north-facing). That was a success.

A year later I put up another 40 odd  (E and W facing)

That was November 2018.

All still Rocksolid, I'll be doing it again.

Oh, and the sticky tape is called VHB4950 by 3M. ( 25mm x 30m rolls I think they were) - bloody expensive, over a grand a roll, I think closer to 2K.

If you read up on it, it's tough stuff, the kind of stuff they use for the glass in skyscrapers and such.

 

 

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1 hour ago, phil.g00 said:

This gives the panels two unistruts profile thicknesses over the IBR mounds and probably the equivalent of three over the IBR channels. ( so probably about 100mm gap average).

In hindsight for future roofs, I'll probably make one of those unistrut profiles the double height version.

I also want to say there were about a dozen sheared welds on thos frames I took down. You couldn't see them from ground levels, but it was on track fpr a catastrophic failure.

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3 hours ago, Jaco de Jongh said:

In theory, maybe, so i thought, until I saw pigeons breeding under the panels 2 weeks back... 

You get the exception to the rule 😉 fact is it gets really hot under solar panels that is why you need a gap between the roof and the panels for air flow your panels loose efficiency when they get too hot 😉Panel temperature has a large effect on efficiency. A 20° Celsius increase in panel temperature can reduce efficiency by as much as 40%. Natural convective air cooling around the panels is essential to ensure efficiency losses are minimised.

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26 minutes ago, SteveFury said:

Panel temperature has a large effect on efficiency. A 20° Celsius increase in panel temperature can reduce efficiency by as much as 40%.

Very interesting figures, i never saw them interpreted like this before. If you look at a spec sheet of a normal Canadian solar panel, you will see 0.37% per degree. Do you mind sharing the 20 degree vs 40% theory. I need to size my future arrays accordingly if this figures are correct 😉. For interest sake, is this 20 degree differential measured from 0 degC or from 20 degC or only after 25  degC, or does it apply to a 20 degC increase in general. 

Temp.thumb.png.aecbf33646f3952407388fc80f6369b3.png

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25 minutes ago, SteveFury said:

You get the exception to the rule 😉 fact is it gets really hot under solar panels that is why you need a gap between the roof and the panels for air flow your panels loose efficiency when they get too hot 😉Panel temperature has a large effect on efficiency. A 20° Celsius increase in panel temperature can reduce efficiency by as much as 40%. Natural convective air cooling around the panels is essential to ensure efficiency losses are minimised.

I have never measured it, sometimes people guess things and before long they are internet gospel.

Taking a random Artsolar panel, NOCT is  45 deg C +/- 2 deg, and the temp coefficient is - 0.37%/ degree.

20 degree increase is only 7% ish at 65deg C.  

Bear in mind, commercially available parabolic solar cookers, something I am also interested in, can barely boil water.

Add to that non-perfect slopes and aspects of solar panels, I think I'd like to do some real world testing.

I can understand a temp increase, but I think the increase and its effect may over exaggerated.

image.png.6eb460052db4d4c25b95da709ca10274.png

Edited by phil.g00
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7 hours ago, Jaco de Jongh said:

Very interesting figures, i never saw them interpreted like this before. If you look at a spec sheet of a normal Canadian solar panel, you will see 0.37% per degree. Do you mind sharing the 20 degree vs 40% theory. I need to size my future arrays accordingly if this figures are correct 😉. For interest sake, is this 20 degree differential measured from 0 degC or from 20 degC or only after 25  degC, or does it apply to a 20 degC increase in general. 

Temp.thumb.png.aecbf33646f3952407388fc80f6369b3.png

The figures quoted are based on data collected over years on an old solar array so to compare it to a new Canadian solar panel is not necisarily a good example however you are correct in your statement that the specific canadian solar panel looses 0.37% per degree and ps that base line is measured at 25 degrees celcius. So for every degree above 25 degrees celcius the panel looses 0.37% efficiency and every degree below 25 degrees it gains 0.37% efficiency however lets not nitpick there are many scientific research proving that solar panels need ventilation so that heat can dissapate to maintain optimal effeciency of the panels. Unless you prescribe to mounting panels flush with roof structures and claim that panel ventilation is a myth..😉 

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6 minutes ago, SteveFury said:

however lets not nitpick there are many scientific research proving that solar panels need ventilation so that heat can dissapate to maintain optimal effeciency of the panels. Unless you prescribe to mounting panels flush with roof structures and claim that panel ventilation is a myth..😉 

The ventilation was never the issue in question, your  exaggeration of the facts were though. Misleading facts like that on a public forum can cost a member a lot of money, but as you said. lets not nitpick about something that important. 

Please dont turn this issue to suit yourself, my question was about your figures, not the mounting method. 

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4 minutes ago, Jaco de Jongh said:

The ventilation was never the issue in question, your  exaggeration of the facts were though. Misleading facts like that on a public forum can cost a member a lot of money, but as you said. lets not nitpick about something that important. 

Please dont turn this issue to suit yourself, my question was about your figures, not the mounting method. 

You claim that its an exaggeration of facts which it is not it was an example of data collected of a old solar installation on a weather station in Australia old Solar panels and old mounting methods fortunately technology has improved however and it is clear that you are nitpicking the fact is solar panels need ventilation you cannot mount them flush on a roof and the original question was what the best options are for solar structures vs roof type and birds nesting under solar panels and quality solar structures. So yes it could be costly for someone not installing and mounting their panels correctly with quality solar structures and qualified installer. So let us leave it at that I am not on this forum to get involved in fights and tantrums. We are all adults here and we all try to contribute positively well atleast I do so I will admit using the example of an old array was not a good choice next time I will base my examples on new gear 😉

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9 minutes ago, SteveFury said:

You claim that its an exaggeration of facts which it is not it was an example of data collected of a old solar installation on a weather station in Australia old Solar panels and old mounting methods fortunately technology has improved however and it is clear that you are nitpicking the fact is solar panels need ventilation you cannot mount them flush on a roof and the original question was what the best options are for solar structures vs roof type and birds nesting under solar panels and quality solar structures. So yes it could be costly for someone not installing and mounting their panels correctly with quality solar structures and qualified installer. So let us leave it at that I am not on this forum to get involved in fights and tantrums. We are all adults here and we all try to contribute positively well atleast I do so I will admit using the example of an old array was not a good choice next time I will base my examples on new gear 😉

I am not talking about the mounting methods. Once again, i ask you not to put words in my mouth.. not once did i dispute the fact that there should be ventilation. It cant be that difficult to understand what my question is about, can it??

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Just now, Jaco de Jongh said:

I am not taking about the mounting methods. Once again, i ask you not to put words in my mouth.. not once did i dispute the fact that there should be ventilation. It cant be that difficult to understand what my question is about, can it??

I covered your question what more do you want. Or do you just want to pick a fight..😉

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2 hours ago, SteveFury said:

Or do you just want to pick a fight..

Not at all, you are the one that continue to twist my question into something it never was, I am merely correcting you, nothing to fight about. 

O yes, can you please post the results of that test here. It would be interesting to see that figures and how they logged the data. My own installation is done with old discontinued panels and they are installed in Phalaborwa, not many places in SA can match our temperature. I would love to compare the results from the Australian test to that of mine... The highest loss due to temperature that I personally recorded was just below 8% on my total array size and that was on an extremely hot day...  

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@phil.g00 @Jaco de Jongh. I have to agree with you guys and the fact that we require real world up to date details and test. @Jaco de Jongh if you have done this test then that's fantastic info for members. 

This is a very interesting topic. Let's all keep to healthy debate. I know we are all very passionate and that sometimes gets the better of us.

Thanks all.

Jay

 

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1 hour ago, Energy said:

@Jaco de Jongh if you have done this test then that's fantastic info for members. 

I like to tinker and mess with bird brained ideas, all for the sake of just knowing. 

One summer some time ago i mess with the idea of cooling my panels with installing a pipe with sprayers on the top end of my panels. My panels were adjustable so i had them on the correct angle for the specific time of the year. I chose a few very hot days up here (Ambient in the mid 40s), waited for for peak period (Between 11H30 and 12H00) and switched on all the loads in my house. I compared the PV production before and after opening the water. I had 12 x 260 watt panels connected. 3120Wh and could record a 240-250 watt (7.7-8%) increase in production with the water open. The smallest pump I could find with the correct head and flow ratings were .25kw so my conclusion was that I would gain nothing by cooling the panels as my pump would be consuming the extra generation. (although the test was done with municipal water, so no pump needed, i planned to install a pump and use water from 2 x 5000 l tanks as i did not want to wast municipal water.) 

The test was repeated some time later after adding another 12 panels and mounting them on the roof at a fixed angle. Now with 6240 whp on the roof there was an approximate 450 watt increase in production and again with a bigger pump (0.37kw) it did not make sense to cool the panels. 

I messed with this idea for some time, but decided its just not worth it. 

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19 hours ago, phil.g00 said:

There existing frames didn't move because of gravity, they were actually free standing, self-welded monstrosities that took 4 men to lift.

I sound like I'm against perfectly tilted frames. I am not, but if you can't see them from space they don't count.

2637bbdd-51e4-4048-bed7-3d65012e4a9a.JPG

c75fec29-fee8-4ed2-9c82-c8f8334068a6.JPG

Edited by phil.g00
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On 2020/08/15 at 7:52 AM, Jaco de Jongh said:

I like to tinker and mess with bird brained ideas, all for the sake of just knowing. 

One summer some time ago i mess with the idea of cooling my panels with installing a pipe with sprayers on the top end of my panels. My panels were adjustable so i had them on the correct angle for the specific time of the year. I chose a few very hot days up here (Ambient in the mid 40s), waited for for peak period (Between 11H30 and 12H00) and switched on all the loads in my house. I compared the PV production before and after opening the water. I had 12 x 260 watt panels connected. 3120Wh and could record a 240-250 watt (7.7-8%) increase in production with the water open. The smallest pump I could find with the correct head and flow ratings were .25kw so my conclusion was that I would gain nothing by cooling the panels as my pump would be consuming the extra generation. (although the test was done with municipal water, so no pump needed, i planned to install a pump and use water from 2 x 5000 l tanks as i did not want to wast municipal water.) 

The test was repeated some time later after adding another 12 panels and mounting them on the roof at a fixed angle. Now with 6240 whp on the roof there was an approximate 450 watt increase in production and again with a bigger pump (0.37kw) it did not make sense to cool the panels. 

I messed with this idea for some time, but decided its just not worth it. 

https://www.pv-magazine.com/2020/03/31/cooling-down-pv-panels-with-water/

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On 2020/08/15 at 7:52 AM, Jaco de Jongh said:

I like to tinker and mess with bird brained ideas, all for the sake of just knowing. 

One summer some time ago i mess with the idea of cooling my panels with installing a pipe with sprayers on the top end of my panels. My panels were adjustable so i had them on the correct angle for the specific time of the year. I chose a few very hot days up here (Ambient in the mid 40s), waited for for peak period (Between 11H30 and 12H00) and switched on all the loads in my house. I compared the PV production before and after opening the water. I had 12 x 260 watt panels connected. 3120Wh and could record a 240-250 watt (7.7-8%) increase in production with the water open. The smallest pump I could find with the correct head and flow ratings were .25kw so my conclusion was that I would gain nothing by cooling the panels as my pump would be consuming the extra generation. (although the test was done with municipal water, so no pump needed, i planned to install a pump and use water from 2 x 5000 l tanks as i did not want to wast municipal water.) 

The test was repeated some time later after adding another 12 panels and mounting them on the roof at a fixed angle. Now with 6240 whp on the roof there was an approximate 450 watt increase in production and again with a bigger pump (0.37kw) it did not make sense to cool the panels. 

I messed with this idea for some time, but decided its just not worth it. 

https://www.pv-magazine.com/2020/03/31/cooling-down-pv-panels-with-water/

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