Solar Panel Wire - Gauge Size? Where to buy from?

[demonboy]

I have three 40w solar panels giving me a total of 120w (obviously) and need to work out the wire gauge as the current wire needs replacing. The distance is no more than 5m from panels to regulator that charges my 12v battery bank. Two questions: what gauge wire should I be looking at and where can I buy decent marinsed cable for the job?

 

[ex-Gladys]

Quick answer, as big as you can... There's no point in not doing, since you only install once. I have about 8 metres length, and have gone for overkill... it's twin core about 4mm2 as I recall

BArden who supplied my panels, supplied the cable

 

[VicS]

The required wire gauge will depend upon the cable run length.


Numerous calculators on line to enable you to determine the size

eg http://www.freesunpower.com/wire_calc.php

Note that this one uses cable run length but others use the total "there and back figure". Use 3% for the percentage volts drop.

the result is in AWG but plenty of tables out there to convert to mm² if required

If you take 10 amps ( but the max current will not be as high as that) and 16ft you get 11 AWG

11AWG is just over 4 mm² So 4mm² will do but perhaps make it 5mm²

 

[nedmin]

I used white 3core 4mm ordinary household flex.Easy to run, if you fit a controller it wont be marinised so why not use ordinary flex? Unless you are at sea 24hrs x7 i cant see a problem.I spray all my connections anyway. F.I. The most current out of 2x80 watt panels I ve had is 10amps.Even when dull I get 2amps in mid day.Never used my generator this year.Over the moon so far.

 

[demonboy]

If you take 10 amps ( but the max current will not be as high as that) and 16ft you get 11 AWG

11AWG is just over 4 mm² So 4mm² will do but perhaps make it 5mm²

Nice one, Vic, just the answer I was looking for. I suspect the cable I am replacing was 5mm2 anyway.

 

[V1701]

I've bought cable & connectors from these folk, you can almost certainly find them cheaper on ebay though...

 

[pappaecho]

If you want a walk in service you will find that shops specialising in Hi Fi for cars will keep a range and 4mm and 5 mm cables, at not too outrageous prices.

 

[whiteoaks7]

You want low resistance so use big cores - speaker cable is good. One point often missed is that wire running exposed on deck rapidly gets its insulation degraded by UV to the point where the insulation cracks off. There's no real answer to this other than using a conduit of some kind (although black wire is good because it is loaded with carbon black - a good UV shield).

David Berry