Solar panel coverings?

[ianp]

A quick question to those in the know. What is the surface covering of the usual MH roof top solar panel please? Are they glass and if so about what thickness?
I ask as I have the offer of a good German made 'domestic' panel that is fitted with 4mm glass and wonder if this is suitable for use on the MH roof?

cheers

 

[cyberyacht]

I wouldn't think a 'domestic' panel is designed for vibration plus 4mm glass means it'll weigh a ton.

 

[Raul]

The size it depends on number of cells and watts. Yes you can use it as long as you got a mppt controller, I have two on my roof, and they are superior compared to the leisure small panels.

 

[Gromett]

Usually 3-4mm of Low Iron toughened/Tempered glass.

How do I know? I made a DIY solar panel many years ago when it was cheaper to make your own than buy (by quite a margin).

 

[ianp]

The size it depends on number of cells and watts. Yes you can use it as long as you got a mppt controller, I have two on my roof, and they are superior compared to the leisure small panels.

Excellent and thank you for the reply Raul. The brand is 'Sunset' and the model is the AS 280/60 which is 280 W output with a footprint of 1650 x 1000 x 50

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[Raul]

Good panel, the classic 1.65x1m, 60 cell with a 31ish volts vmp and about 38voc. You need a mppt of 50v minimum for open circuit voltage. The minimum victron , would be the 100/20 model.

 

[tonyidle]

The size it depends on number of cells and watts. Yes you can use it as long as you got a mppt controller, I have two on my roof, and they are superior compared to the leisure small panels.

As do I. Well one on the roof and another waiting to be installed.

 

[gus-lopez]

4mm glass means it'll weigh a ton.

4mm is minimum thickness these days for windows etc.3mm only allowed for picture frames.

 

[Raul]

I think for hail stones and snow load rating, all panels are minimum 4mm. It’s the heaviest part in a panel assembly. The old 50-40mm frames can take a huge load, but the modern 35-30mm frames, not so sure.

 

[ianp]

So the current plan is that as we have two roof rails with 'flanged' slots within the inside faces of the rails. We intend to mount a subframe to these using 'slide in tee bolts' and sit the panel on to the subframe. This will mean the panel has a gap between the MH roof and its underside of about 5 or 6 inches. Can anyone see an issue with this? I'm not too sure how much if any 'wind' noise it may generate but as we seldom exceed 50/ 60 mph I'm not too sure that will be an issue. The other thing that may raise its head is the aerodynamic lift on the panel but is this any different with 5 inches as opposed to the usual one inch or less? Are there ways to mitigate any noise and or lift that is not too onerous?

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[cyberyacht]

Any sort of framing will affect fuel consumption. The more complex, the more drag. One often sees recommendations to remove roof racks on cars to reduce drag.

 

[headlight]

So the current plan is that as we have two roof rails with 'flanged' slots within the inside faces of the rails. We intend to mount a subframe to these using 'slide in tee bolts' and sit the panel on to the subframe. This will mean the panel has a gap between the MH roof and its underside of about 5 or 6 inches. Can anyone see an issue with this? I'm not too sure how much if any 'wind' noise it may generate but as we seldom exceed 50/ 60 mph I'm not too sure that will be an issue. The other thing that may raise its head is the aerodynamic lift on the panel but is this any different with 5 inches as opposed to the usual one inch or less? Are there ways to mitigate any noise and or lift that is not too onerous?

I fitted a panel to my roof rack earlier this year.
I didn't use a subframe I just T bolted straight from the roof rack into the panel frame as others have done.
It's been up there about 4 months now with no issues, no noise and no noticeable decrease in mpg.
Some people have reported extra noise and so have fitted a wind deflector in front of the panel.

 

[ianp]

I fitted a panel to my roof rack earlier this year.
I didn't use a subframe I just T bolted straight from the roof rack into the panel frame as others have done.
It's been up there about 4 months now with no issues, no noise and no noticeable decrease in mpg.
Some people have reported extra noise and so have fitted a wind deflector in front of the panel.

That's interesting to hear ! So you have no additional support for the panel across the span of the roof rails which in my case would be 1500mm. What span is your panel please?

 

[headlight]

That's interesting to hear ! So you have no additional support for the panel across the span of the roof rails which in my case would be 1500mm. What span is your panel please?

1200mm. It's fitted width ways with 3 T bolts on the front and back edges.
I know someone who fitted a 1700mm panel the same way with no problems.

 

[MisterB]

Riv nuts might be worth considering, so you can bolt direct to the fails?

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[ianp]

Good panel, the classic 1.65x1m, 60 cell with a 31ish volts vmp and about 38voc. You need a mppt of 50v minimum for open circuit voltage. The minimum victron , would be the 100/20 model.

Would the 75/15 not suffice in this application Raul?
I am in fact mounting a separate 100w panel also but was thinking in terms of keeping them seperate for a bit of redundancy should one go west! and using two 75/15's. Though if I went 100/20 then maybe I could arrange a switch to join the two in series on those dull dark days of winter.......what do you think?

Ah...just looked at the spec for the 75/15 and see it has a nominal max wattage of 220w......though the output and input from the panel and unit are well within spec on the voltage / amperage front ! So I'd lose about 2amp on the input if restricted which is about 23% at max performance......mmmmm !

 

[Raul]

I remember yiu said tbe oanel is 280w?
Then 280w /14.4v =19.44A. Hence i suggested the 20A controller. You could fit the 15A but, you will always be limiting the panel to 216W max.

 

[ianp]

Raul
Just a quickie quality question that you may know......have the Photonic Universe MPPT units got a reasonable / good reputation as they are very well priced compared to the Victron units?
I was thinking of something along the lines of the 40a unit with over 500w and 100v input..... a much larger footprint physically but very accommodating electrically and very well priced....but are the good enough?

 

[Raul]

They are ok if you intend no further upgrades and be done. Victron is more versatile, modular future proof, and holds decent re sell value. Also 5 year guarantee.

 

[Furry Paws]

So the current plan is that as we have two roof rails with 'flanged' slots within the inside faces of the rails. We intend to mount a subframe to these using 'slide in tee bolts' and sit the panel on to the subframe. This will mean the panel has a gap between the MH roof and its underside of about 5 or 6 inches. Can anyone see an issue with this? I'm not too sure how much if any 'wind' noise it may generate but as we seldom exceed 50/ 60 mph I'm not too sure that will be an issue. The other thing that may raise its head is the aerodynamic lift on the panel but is this any different with 5 inches as opposed to the usual one inch or less? Are there ways to mitigate any noise and or lift that is not too onerous?

This is how mine are installed on my iveco Daily Bus conversion they are 2 x 250watt domestic solar panels and my batteries are usually full by about 7:30 am even in the uk LOL