Using Domestic Solar Panels on Motorhomes

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Lizbiebrowne

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I want to fit about 400 W of solar panel to my motorhome roof for use in conjunction with my already installed MPPT controller which can handle up to 430 W and Voc of 50 V.

If I look on the 12V Planet website I could buy two 175 W Victron solar panels for around £270, advertised for use with 12 V systems on motorhomes and boats.

However, if I search Google for a 400 W solar panel I find that I can buy various domestic panels at around this power level all for less than £100. For example, the one below is £83, a 405 W panel with a Voc of 37 V.

Is there any reason why I shouldn’t fit this cheaper one?

LONGi Solar Hi-MO 5m 405WP Full Black PV Module LR5-54HIB-405M

LONGi's high-efficiency PV modules are widely used all over the world, from alpine grasslands to desert wastelands, and from ponds and vegetable beds to household dwellings. LONGi's ultra-high-value PV module products continue to benefit customers and local economy with its advantages of higher...
www.cityplumbing.co.uk www.cityplumbing.co.uk
 
The only things that spring immediately to mind are weight and size. The fixings would also have to be much more substantial than the smaller motorhome versions.
 
I think the mounting is different Domestic mounting uses a rail and T bolts and clamps to hold in place. Motorhome panels are screwed in place through the frame then the brackets bonded to the MH roof.
 
I suspect that domestic panels aren't designed to cope with the same wind loading. Driving at 60mph into a 40mph head wind, and then an HGV passes in the other direction... I'd not volunteer to be the first person to try a barn door sized domestic panel on my van roof in that scenario!
 
It does have three diodes .not sure how you would wire that up to your controller.

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Op, get yourself a longi 430w and fit it with some ally angle to the roof. Domestic panels are stronger, more robust, and actually have accreditations, compared to leisure small panels. They have better load resistance, better frame, and do produce more than the nameplate in ideal conditions.
I have two on my van.
 
Raul said:
Op, get yourself a longi 430w and fit it with some ally angle to the roof. Domestic panels are stronger, more robust, and actually have accreditations, compared to leisure small panels. They have better load resistance, better frame, and do produce more than the nameplate in ideal conditions.
I have two on my van.
Click to expand...
Agreed - have 1 x 455W domestic panel on my PVC and not needed EHU at all this year.
 
esoarer said:
Agreed - have 1 x 455W domestic panel on my PVC and not needed EHU at all this year.
Click to expand...
Raul said:
Op, get yourself a longi 430w and fit it with some ally angle to the roof. Domestic panels are stronger, more robust, and actually have accreditations, compared to leisure small panels. They have better load resistance, better frame, and do produce more than the nameplate in ideal conditions.
I have two on my van.
Click to expand...
Thanks both, that’s encouraging to know. Can you say how you fitted them? It seems like you have to use clamps that are then bolted down. Or did you find you screw into the side of the panels?
 
I have a 250W domestic panel in use now for 3 years. The weight per square metre is the same as "motorhome" panels. The standard of construction is identical. I have a second one to install when a fine day, enthusiasm, and time align.
 
Mine are fitted with renusol rail and clamps; because i had them from leftover jobs.
If i did not had them, i would use ally angle 50mm x 50mm, and screw to the frame.
 
Raul said:
Mine are fitted with renusol rail and clamps; because i had them from leftover jobs.
If i did not had them, i would use ally angle 50mm x 50mm, and screw to the frame.
Click to expand...
Which is how mine is installed. The beauty of alloy angle brackets is that you can decide your own footprint if installing using adhesive.
 
Raul said:
Op, get yourself a longi 430w and fit it with some ally angle to the roof. Domestic panels are stronger, more robust, and actually have accreditations, compared to leisure small panels. They have better load resistance, better frame, and do produce more than the nameplate in ideal conditions.
I have two on my van.
Click to expand...
Accreditations for a very different use case. It doesn't matter how strong the rails are if the air pressure from a passing truck blows the panel out. Or they've got a lower IP rating so they don't cope with salt spray getting underneath them. Or they get vibration damage.

I'm not saying they aren't suitable. They might well be fine. But they definitely aren't designed with being vehicle mounted in mind.
 
Guigsy said:
Accreditations for a very different use case. It doesn't matter how strong the rails are if the air pressure from a passing truck blows the panel out. Or they've got a lower IP rating so they don't cope with salt spray getting underneath them. Or they get vibration damage.

I'm not saying they aren't suitable. They might well be fine. But they definitely aren't designed with being vehicle mounted in mind.
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Certainly wouldn't get any warranty/guarantees on the panel.

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Last edited:
Guigsy said:
Accreditations for a very different use case. It doesn't matter how strong the rails are if the air pressure from a passing truck blows the panel out. Or they've got a lower IP rating so they don't cope with salt spray getting underneath them. Or they get vibration damage.

I'm not saying they aren't suitable. They might well be fine. But they definitely aren't designed with being vehicle mounted in mind.
Click to expand...
And yet people have been using them for years with no problems. See the link I posted earlier.
 
Guigsy said:
Accreditations for a very different use case. It doesn't matter how strong the rails are if the air pressure from a passing truck blows the panel out. Or they've got a lower IP rating so they don't cope with salt spray getting underneath them. Or they get vibration damage.

I'm not saying they aren't suitable. They might well be fine. But they definitely aren't designed with being vehicle mounted in mind.
Click to expand...
Look at specs for yourself on both.
Domestic panels have a superior insulation allowing systems up to 1500v. Rest assured the Ip is better.
 
Just so you know where I am coming from. I actually built a solar panel from scratch many years ago so know the construction methods used.

I do not know this for certain, but I believe that the panels are all made exactly the same. The only variation will be the thickness of the glass and the gauge of the aluminium profile.
The cells, the bonding and the sealing systems will all be identical.

The glass thickness and aluminium profile size will be dictated by structural/mechanical requirements and will scale with size.

The production line will not be run for a specific application. They will not know that this set of panels is going to motorhomes, this set is going to house, this set is going to commercial out on the field big farms.

They will be produced to a specific wattages using a set type of cell.

The differentiation comes later. With 12v/100w+ ones more likely to be going to leisure so will unlikely to have any tests done beyond basic operations.
The 24v and 48v ones 200W+ will likely have some certification tests. And the 48V 400W ones getting the full tests.

There will be some 12v ones that get the full certification tests and some 48V ones that don't. The latter may be due to blemishes or failure to meet basic tests 1st.

But I don't think there is any difference in the actual manufacturing process or materials used.

I honestly don't see what they can do differently to make them better IP rated or structurally better.

Just my opinion.
 
PS: A quick break down of how to make a solar panel.
You solder tab strips to the cells, then solder the cells in strings.
You then place these strings of cells onto the glass and cover with a sheet of EVA.
DIY you can heat gun the EVA to bond it to the back of the cells. But in a factory I suspect they use a vacuum and an oven to ensure no air behind the EVA sheet.

This is the stage where I was halfway through heat gunning the EVA
1701187623995.png


Once you have them bonded using the EVA sheet you can use Tyvek or other waterproof material to seal it in. I suspect that they put the tyvek on at the same time as the EVA with the EVA both bonding the cells in and the Tyvek to the EVA.

The Tyvek is to stop moisture getting in and should be sealed round the edged with silicon or similar.

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I have had a 250w domestic house panel on my van for a year now been to spain and back 2 times also to scotland not had a problem yet. I am getting 3 x 400w panels delivered tomorrow hopefully
 
Gromett said:
Just so you know where I am coming from. I actually built a solar panel from scratch many years ago so know the construction methods used.

I do not know this for certain, but I believe that the panels are all made exactly the same. The only variation will be the thickness of the glass and the gauge of the aluminium profile.
The cells, the bonding and the sealing systems will all be identical.

The glass thickness and aluminium profile size will be dictated by structural/mechanical requirements and will scale with size.

The production line will not be run for a specific application. They will not know that this set of panels is going to motorhomes, this set is going to house, this set is going to commercial out on the field big farms.

They will be produced to a specific wattages using a set type of cell.

The differentiation comes later. With 12v/100w+ ones more likely to be going to leisure so will unlikely to have any tests done beyond basic operations.
The 24v and 48v ones 200W+ will likely have some certification tests. And the 48V 400W ones getting the full tests.

There will be some 12v ones that get the full certification tests and some 48V ones that don't. The latter may be due to blemishes or failure to meet basic tests 1st.

But I don't think there is any difference in the actual manufacturing process or materials used.

I honestly don't see what they can do differently to make them better IP rated or structurally better.

Just my opinion.
Click to expand...
Nice one Gromett, I will add that fears competition at the top, has delivered better and better panels as they come with innovative methods to out do each other. PERC, LID, lattice buss bar, high quality shottky, iron free glass and later the half cut cells to avoid micro cracks, and make more use of the ingot, and the space on the panel surface; all of this and many more qualities, will not appear in the small leisure panels, even Victron panels are very very old school, compared to a high quality tier 1 class A panel. The best quality of the cells are flashed and selected then best ones goes to Tier 1 panels, the rest are going to the rest of the panels. As for mechanical load, Tier 1 can take 1m high of snow, the leisure panels have much thinner glass, less snow load and more fragile to vibrations.
 
Raul said:
iron free glass
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That is standard across the board as I understand it. I had to order that glass specially for my DIY project. It was the most expensive part from memory.
 
The 40w leisure one fitted to my autocruise packed up after 7 years. Replaced with renogy 50w plus another 200w. The array on my house roof is still going strong 8 years later at almost the same output. I would have no hesitation using domestic ones on the van, if only I had enough space!

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Raul said:
Op, get yourself a longi 430w and fit it with some ally angle to the roof. Domestic panels are stronger, more robust, and actually have accreditations, compared to leisure small panels. They have better load resistance, better frame, and do produce more than the nameplate in ideal conditions.
I have two on my van.
Click to expand...
I have 2 domestic 250w panels on my Iveco Daily
 
Had 340w domestic panel fitted to my van over a year and half been to Morocco and back - no problems at all and hardly ever have to use EHU even in the UK! Currently on my way back to Morroco for the winter - I’d say go for it!
 
EuroTrotters said:
do Domestic Panels perform better on cloudy days ?
Click to expand...
Only some panels do that. The ones with heterojunction cell construction do, but only few manufactuters offer this: Rec, Panasonic, Burger Mayer, and there is another one can't remember the name. I think Panasonic has closed shop for panels, only in US they still do.
I almost forgot, CIGS work very well in low light.
 
I have used domestic panels now for over 7 years, firstly a 280w panel on my caravan, and then a 360w panel on my M/H. The only difference that I could see is that the domestic panels tend to be higher voltage, so use a good quality mppt controller that can take the higher input voltage. (280w panel vas 57v, the 360w panel is 36v)
The low light performance is a function of the controller, my victron controller will charge down to 8v input.
So at the light level that an 18v panel (Normal 12v panel) is at 8 v, my 32v panel is outputting 16v. So when the light is lower and say is outputting 10 v on my panel, I am still getting some charge whereas an 18v panel will be outputting 5v and not charging.

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