solar panel cablling

Submitted: Monday, Dec 02, 2013 at 15:20
ThreadID: 105348 Views:2311 Replies:12 FollowUps:15
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We have two 60W solar panels roof-mounted on our goldstream wind-up camper. Up until recently, they have worked perfectly to keep our two batteries charged - the main draw on the batteries being our electric-only fridge.

The cable from the panels is connected to an anderson plug mounted under the trailer which is wired into the solar panel regulator. The wiring into the anderson plug from the solar panels broke, so my husband re-attached the plug - it broke again and we now realise that the actual copper wiring is exceptionally poor quality & is crumbling. We obviously need to replace the cable.

My question is where do we go to purchase good quality cabling, and what should we be asking for??? We have read, and tried to absorb, an article on exploreoz regarding solar panels & cables, but it has left us feeling less confident of buying the correct sized cable.
We would appreciate some advice on this to enable us to properly make the necessary repairs.

Thanking you in advance,

avidcamper
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Reply By: Member - Rosco from way back - Monday, Dec 02, 2013 at 15:51

Monday, Dec 02, 2013 at 15:51
Any good/competent 12V mob e.g. Springers or ABR could advise and supply the correct twin cable. Just give them all the details (length of cable run etc etc)
AnswerID: 522478

Follow Up By: avidcamper - Monday, Dec 02, 2013 at 16:43

Monday, Dec 02, 2013 at 16:43
Thankyou for your suggestion Rosco - sounds good!
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FollowupID: 803554

Reply By: Herbal - Monday, Dec 02, 2013 at 15:57

Monday, Dec 02, 2013 at 15:57
It sounds like you don't have copper wire...Maybe some other metal mixed in to make an alloy...Copper should not crumble.

Any place with a name you know, like Bunnings or Mitre10 etc. Or of course you could go to a solar shop or electrical shop.

Tell them you want pure copper wire...

Get the largest size that will fit...An easy way to find out what the largest size is, is with drill bits. I assume you will have some drill bits. Simply find the largest drill bit that you can fit into the terminals of your regulator and that will be the largest wire you can use. It should be around 3 or 4mm dia.
AnswerID: 522479

Follow Up By: avidcamper - Monday, Dec 02, 2013 at 16:42

Monday, Dec 02, 2013 at 16:42
Hi Herbal,

Thankyou for your help.

It definitely seems to us that the cable supplied with the panels is not pure copper but some sort of alloy - as you say, copper should not crumble.

The regulator is located inside the trailer close to the battery. The solar panels' cable runs down the outside of the trailer & plugs in to the anderson plug which we assume connects to the regulator which is connected to the batteries (our trailer is second-hand so we don't know the exact details of the internal wiring).

We feel the cable we need to replace is not only of inferior quality, but most likely also too narrow in diameter .... all very confusing!

Regards,

avidcamper
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FollowupID: 803553

Reply By: Ross M - Monday, Dec 02, 2013 at 16:01

Monday, Dec 02, 2013 at 16:01
avid
Although not a Jaycar line, they do sell twin core red/black in 3mm 4mm 5mm 6mm with a plastic sheath over it.

The 5mm will be quite reasonable for the current over the distance you are working and not cause much voltage drop.

What you should aim for, if not already done, is the to feed the regulator and have it as close as practical to the battery. Then the maximum energy/voltage level available is then regulated and delivered to the battery/ies.

The 5mm, that is the dia of the red or black over the inner copper will flow 27 amps without significant heating of the cable due to it's own resistance, so 120W is only a few amps, maybe 8 on a good cool day and so that size should be ok. $2.75/m

6mm is more better of course.

You may be able to source similar off the WWW ebay thingo at a cheeeeper price.

Make sure non of the cables are free swinging as movement will cause fractures and failures in anything. Cables ties are your friend.
AnswerID: 522480

Follow Up By: avidcamper - Monday, Dec 02, 2013 at 16:58

Monday, Dec 02, 2013 at 16:58
Hi Ross M,

Thankyou for your help.

The regulator is installed close to the batteries (good!) .... our problem is the cable from the solar panels - obviously of inferior quality.

The panels are roof-mounted & the cable runs down the side of the camper to the anderson plug - 2.5 metres in length - do you think that we should aim for the 6mm rather than 5mm? What I don't understand, is the difference between 5mm & 5mm²????

Regards,

avidcamper
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FollowupID: 803556

Follow Up By: Ross M - Monday, Dec 02, 2013 at 18:04

Monday, Dec 02, 2013 at 18:04
Avid
I use 5mm (cos i had it) on a similar length run with 160W (2 panels) and that is OK.
Bigger is better, but if the 5mm is sufficient then 6mm is not going to be any more benefit but has capability for expansion of panels though.
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FollowupID: 803563

Follow Up By: Terry 12 - Monday, Dec 02, 2013 at 21:58

Monday, Dec 02, 2013 at 21:58
( What I don't understand, is the difference between 5mm & 5mm²?? )

5mm is the width of the copper core as a diameter, 5mm across.
5mm² is the total end area of all the strands that make up the wire, this could be 40 of 50 very small strands or copper, as one solid square of wire it would be 2.24mm x 2.24mm ( 5mm² )
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Reply By: Member - wicket - Monday, Dec 02, 2013 at 16:51

Monday, Dec 02, 2013 at 16:51
why not support one of the business members here.
this page shows what you're after but best to ring or email him for exact details

cable for solar here
AnswerID: 522482

Follow Up By: Member - Bruce C (NSW) - Monday, Dec 02, 2013 at 17:08

Monday, Dec 02, 2013 at 17:08
Here is another vote for ABR Sidewinder.

Derek Bester' products are first class and not expensive. I have purchased from him many times.

6mm square (mm2) is what you need from your regulator to your batteries and then on to an anderson plug for the best results in this situation.

A.B.R. 6mm cable

Cheers, Bruce.
At home and at ease on a track that I know not and
restless and lost on a track that I know. HL.

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Follow Up By: Member - Bruce C (NSW) - Monday, Dec 02, 2013 at 17:13

Monday, Dec 02, 2013 at 17:13
Ooops.
Sorry wicket I should have checked your link before posting mine.

Cheers, Bruce.
At home and at ease on a track that I know not and
restless and lost on a track that I know. HL.

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Reply By: bks - Monday, Dec 02, 2013 at 17:18

Monday, Dec 02, 2013 at 17:18
There is a crowd who are regularly at the camping shows called "home of 12 volt" who have the cable already made up with the anderson plugs connected. I have found them to be quite good. Home of 12 volt

I also found that sometimes if the cable is a little to large for the regulator, it is not the cable connector (if thats the correct term) but the plastic around the hole where you insert the cable that is the problem. I drilled out the hole and found I then had plenty of space to insert the larger cable.

Hope that makes sense.
AnswerID: 522486

Follow Up By: avidcamper - Monday, Dec 02, 2013 at 18:47

Monday, Dec 02, 2013 at 18:47
Thankyou one and all for your responses - we really appreciate all your help.

To clarify - the connection between the regulator & batteries is not in question - that is a permanent installation inside our trailer.

The problem lies with the cable connecting the regulator to the solar panels. We will follow up on the link posted earlier (thankyou) and call for advice before purchasing - with everyone's helpful suggestions we do feel more confident of making the right decision.

Thankyou!

avidcamper
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Follow Up By: Member - Toyocrusa (NSW) - Monday, Dec 02, 2013 at 20:07

Monday, Dec 02, 2013 at 20:07
Avidcamper. The heavier cable still could be too large for the fittings on the solar panels though. Depending on how they are wired and connected. If you do use the heavier cable and find it too big you may have to cut some of the end copper away to allow it to fit into the connector. This is normally acceptable to do in this instance. Cheers,Bob.
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FollowupID: 803567

Reply By: Member - Bruce C (NSW) - Monday, Dec 02, 2013 at 17:21

Monday, Dec 02, 2013 at 17:21
Hi Avidcamper,

It has not been mentioned so far but it is accepted that 4 mm2 is the preferred size from the panels to the regulator.
As I explained in follow up to Wicket a minimum of 6 mm2 for regulator to batteries but keep the reg to battery cables as short as you can so that you minimize line drop or losses.
Ebay is also awash with sellers selling suitable cable but you can depend on ABR for a quality product and good advice.

Cheers, Bruce.
At home and at ease on a track that I know not and
restless and lost on a track that I know. HL.

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AnswerID: 522487

Follow Up By: Brian 01 - Monday, Dec 02, 2013 at 20:14

Monday, Dec 02, 2013 at 20:14
I'm at a bit of a loss as to why there would be a blanket acceptance of 4mm2 being the preferred size from the panels to the controller but then 6mm2 from the controller to the battery.
First point would be that the length of run from the panels to the controller is likely to be considerably longer than that from the controller to the battery and therefore should have the larger cable size.
Second point is that if using a series type controller (PWM) then the current in both sections of wire is the same, so why have different sizes?
If using an MPPT controller, then there may be a slightly larger current in the controller to battery cable, but even so, the larger cable for the longer run is still sensible practice.
Third point is that surely the length of the run, the current being carried and the tolerable voltage drop are the wire size deciders, not some rule of thumb.
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Follow Up By: Member - Bruce C (NSW) - Monday, Dec 02, 2013 at 20:55

Monday, Dec 02, 2013 at 20:55
Hi Brian,
There is no blanket acceptance of 4mm, just a general acceptance from most of the reading I have done on the subject and from the more experienced installers here. Also it works fine on my installations.

I guess that the 4mm theory it is due to the higher voltage at the panels (19 to 21V) where as the reg drops that down to 12V to the battery connections. This is why it is generally accepted that a larger sized but shorter cable is required between reg and battery.

This is my understanding on the subject anyway.

Accepted that the larger the better when dealing with DC but there is such a thing as over engineering I guess and that may account for the 4mm versus the 6mm thinking.

Mind you, I am happy to be enlightened if I am misguided on this.

Cheers, Bruce.
At home and at ease on a track that I know not and
restless and lost on a track that I know. HL.

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Follow Up By: Brian 01 - Monday, Dec 02, 2013 at 23:15

Monday, Dec 02, 2013 at 23:15
If the controller is a PWM type as most still are, then the voltage of the panel is pulled down to that of the battery, so you won't see anywhere near 19 to 20v on those cables when the controller is on, 13 to 14 is more likely, and that is the exact same voltage that will be present in the other bit of wire as well.
Even if it is an MPPT controller where the voltage at the panels will be higher during the boost stage, it will still absorb and float in PWM mode, with all voltages being the same throughout, so, no matter which size you use, there really is no point in different size cables.
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FollowupID: 803575

Follow Up By: Ross M - Tuesday, Dec 03, 2013 at 08:58

Tuesday, Dec 03, 2013 at 08:58
Any percentage of loss through voltage drop in panel to reg is going to cause some loss of efficiency. You only need a small resistance to be in the panel to reg to batt line and you will easily cause 1/3 of the charging ability to be lost.
It is because of the difference of the resulting applied voltage level over and above the battery level.
With an faulty/affected resisting circuit (wire too small) the applied voltage may be only slightly above the battery voltage and than means the current energy won't flow very much at all = less performance.

You want the reg to be able to deliver and the regs characteristics to control charge to the battery not the cables cos they aint smart.
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FollowupID: 803586

Reply By: Member - Phil G (SA) - Monday, Dec 02, 2013 at 20:15

Monday, Dec 02, 2013 at 20:15
I got tired of cable corroding in the weather. I now use tinned cable for everything. Get it from any boat shop such as Whitworths or BCF, or is now being stocked in some sizes at Jaycar.
This link is the stuff I'd use in your application.
AnswerID: 522495

Reply By: briann532 - Monday, Dec 02, 2013 at 20:29

Monday, Dec 02, 2013 at 20:29
avid camper,
where are you?
I may be able to help.

AnswerID: 522497

Follow Up By: avidcamper - Monday, Dec 02, 2013 at 22:27

Monday, Dec 02, 2013 at 22:27
We are Sydneysiders - Burwood area ...........
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FollowupID: 803574

Reply By: briann532 - Tuesday, Dec 03, 2013 at 15:13

Tuesday, Dec 03, 2013 at 15:13
I'm in Sydneys North West - Rouse Hill.

I have some surplus 4.0mm tinned solar cable you are welcome to have.

Our new regs require PV 1-F rated cable so I have some old stock.
When I say old - 6 months old. Not old old if you know what I mean.....

You're welcome to it.
Brian
AnswerID: 522518

Follow Up By: avidcamper - Tuesday, Dec 03, 2013 at 22:53

Tuesday, Dec 03, 2013 at 22:53
We very much appreciate your kind offer, Brian - however we may end up purchasing online & taking advantage of home delivery due to our current business time constraints (call it 'end-of-year-itis'!!).
Thankyou again for your offer.
avidcamper
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FollowupID: 803624

Reply By: Bob Y. - Qld - Tuesday, Dec 03, 2013 at 20:00

Tuesday, Dec 03, 2013 at 20:00
Avid,

Can recommend Marsol Industries, who are Business Members of this site.

Good prices, and prompt service suited me when I recently purchased a couple of panels and some cable.

No affiliation etc

Bob.
Seen it all, Done it all.
Can't remember most of it.

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AnswerID: 522530

Reply By: cookie1 - Wednesday, Dec 04, 2013 at 08:38

Wednesday, Dec 04, 2013 at 08:38
By the sound of it the cable is not UV stabilised, replacing it with the same stuff will see you replacing it again in a short time try this

http://www.jaycar.com.au/productView.asp?ID=WH3121

cheers
AnswerID: 522539

Reply By: avidcamper - Wednesday, Dec 04, 2013 at 13:33

Wednesday, Dec 04, 2013 at 13:33
Thankyou to everyone for all your help & advice.

Armed with all this information, I have been able to phone one of the suggested retailers and ask (relatively!) intelligent questions & can also understand the answers. After a little more investigating on our part as to how the cable is attached to the solar panels, we will then be able to order the correct one.

Thankyou again!

Regards to all,

avidcamper
AnswerID: 522552

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