Solar query

Bouydog

Full Member
I have three 310w panels that Come with 4mm cable on each panel, I am going to connect them in series will 4mm cable be ok to run to the controller.

Thanks
Dave
 

wildebus

Full Member
I have three 310w panels that Come with 4mm cable on each panel, I am going to connect them in series will 4mm cable be ok to run to the controller.

Thanks
Dave
In Series, the current doesn't increase whether using 1, 2 or 3 panels so 4mm will be ok. However, If you are running new cable, I think I would be inclined to use 6mm rather than 4mm as the extra cost is minimal and you will get a lesser voltage drop.

Sounds like a nice Solar Installation you will have there :)
 

Bouydog

Full Member
In Series, the current doesn't increase whether using 1, 2 or 3 panels so 4mm will be ok. However, If you are running new cable, I think I would be inclined to use 6mm rather than 4mm as the extra cost is minimal and you will get a lesser voltage drop.

Sounds like a nice Solar Installation you will have there :)
Thanks for that advice Dave, I will go with the 6mm. Just waiting for a break in the weekend weather to get them on the roof 👍
 

Bouydog

Full Member
Better in parallel so if one goes down it can be switched out of service.
Hi Trev
I am aware of that risk but my very limited understanding of it is that wiring in series fully utilises the functions of an mppt controller and needs less wiring components than parallel. The downside as you say loose one loose them all, also applies to shade. If that happens I will disconnect the duff one and still have the others the connections will be accessible after installation.
Dave
 

SquirrellCook

Full Member
Mine our connected in two pairs, during our Dutch adventure I heard percussion on the roof whilst driving at high speed. I think I've lost a panel now :( can't investigate for a while as I managed to brake my leg whilst out there.
 

Bouydog

Full Member
Ouch to both hopefully it is still attached, mine will be bolted to a rack I have made and the rack bolted to the roof.
May your bones knit quickly.
 

Bouydog

Full Member
That would make sense, I am using rigid panels and i know many people just use adhesive to fix them with no problems but I would constantly worry about them so mechanical fixing for me 😊
 

wildebus

Full Member
I would be very nervous about relying on a non-mechanical adhesion, especially on a glass panel with the aluminium frame. Picture that flying off and going into someones windscreen behind you. Could spoil their day somewhat!
Doesn't matter how good the glue is, you are still very often sticking it to a layer of paint just microns thick with an unknown adhesion quality to the surface below.

I have used non-mechanical fixings on a pair of semi-flexible solar panels.
This is the underside of one of the panels:

Panel Underneath
by David, on Flickr
3M VHB Tape used every 25cm or so along the lengths of the panel; the roof is an unpainted (self-coloured) fibreglass roof and I checked with the manufacturer of the roof AND the manufacturer of the Solar Panels that this tape would be suitable on their product; and finally there are strips across the front to stop airflow going underneath to prevent lift and/or flex at speed (the panel also has a rigid fibreglass backing and does not expand/contract).
As soon as the tape backing tape was pulled off and that panel made contact with the roof it was stuck firmly and could not be shifted a millmetre - and that tape still needs 24-48 hours for full bonding strength!

Ouch to both hopefully it is still attached, mine will be bolted to a rack I have made and the rack bolted to the roof.
May your bones knit quickly.
That is the approach I took - fit tracking to the Roof that in my case is both stuck down with 3M VHB AND mechanically bolted down; and then each panel (have 4 glass panels) is mechanically attached to the tracking with brackets.
Not having the panels glued down makes it very easy to change/adjust anything on a panel if you want to.


Mine our connected in two pairs, during our Dutch adventure I heard percussion on the roof whilst driving at high speed. I think I've lost a panel now :( can't investigate for a while as I managed to brake my leg whilst out there.
Oops on both :(
I think if you have 4 panels on the roof, a combination of Series & Parallel above is the best option on a 12V Battery System (y). Gets you the extra voltage for performance and covers you against shading well.
With 2 or 3 panels, it becomes a choice of either Series OR Parallel - and typically Series will optimize the harvesting performance if having to choose between the two ways.
 

Millie Master

Full Member
The age old and forever repeating chestnut!

As far as I am concerned the only safe sure/certain way of attaching any kind of solar panel is with a mechanical method.

I know me old mate Squiffy might come along and say his panel has been up there on the roof for umpteen years and that is only attached with glue, but as far as I am concerned it is far better to be safe than sorry.

Phil
 

SquirrellCook

Full Member
The first one I bonded to the roof and it failed a few weeks later! Note to oneself never bond panels maybe?
Not wanting to put holes in the roof I bonded Kevlar patches to the roof with studs protruding.
When those panels failed the replacement panels were not the same pitch as my studs!!
Studs ground off and new ones attached, now with slightly curved profile strips of aluminium along the long lengths to improve rigidity.
Front edges of the panels taped to stop air getting under them.
I have consumed a lot of lensun panels. At first they were very good with replacements, but the good service did not last long.
in hindsight, I may have killed some panels by allowing them to move or vibrate. More failed due to manufacturing problems.
I think they have to be handled with the utmost care.
They need to be bonded with no voids underneath.
Then you might have a long service from them.
Assuming I have another duff one, I'm only going to use the cheap £100 ones now.
Betty is getting some stupidly expensive panels of another technology, I hope they are trouble free.
 

trevskoda

Full Member
It's true Trev that the colder the panel the better it works, but flexibles can't flap!
Mine are bolted through using garden fence post clamps,also a seal under them and the panels can be removed from the brackets should the fail,i used a boat deck gland fitted under to take cable through roof.
deck g a.png
 
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