What cable size to use for solar panels?

Submitted: Wednesday, Jun 04, 2008 at 21:23
ThreadID: 58388 Views:2765 Replies:4 FollowUps:1
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Hello

I will have 2x 120w solar panels on the van and may put another one on in the future. What size cable should I use between the panels and the electrical gear in the boot? I've got some 6B&S spare - would that be okay to use or is this a situation where bigger is not better?

John
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Reply By: Dunaruna - Thursday, Jun 05, 2008 at 06:47

Thursday, Jun 05, 2008 at 06:47
In respect to voltage drop and lengthy runs of wire, bigger is always better.

The 6B&S will do nicely.
AnswerID: 307827

Reply By: Grungle - Thursday, Jun 05, 2008 at 07:52

Thursday, Jun 05, 2008 at 07:52
If only a short run then 4mm or 6mm twin core sheathed (not ²mm) is the standard. Most 'loose' panels that are setup on the ground will have 10-20m of 6mm twin sheathed.

You don't need to worry about voltage drop on a solar panel as it is capable of supply in excess of 20V but it is the regulator that controls the voltage. It will drop the panel voltage to around 0.1V higher than battery voltage (at the reg) during boost and absorbtion charges.

Regards
David
AnswerID: 307836

Follow Up By: Boobook2 - Thursday, Jun 05, 2008 at 10:17

Thursday, Jun 05, 2008 at 10:17
True, unless the solar panel has the regulator built in as a lot of the fold up ones do. Then 8AWG or so would be of value over longer runs.
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FollowupID: 573695

Reply By: MEMBER - Darian (SA) - Thursday, Jun 05, 2008 at 09:46

Thursday, Jun 05, 2008 at 09:46
My Collyn Rivers book has detailed formulas to work all this out - suggests that 6mm² ISO cable is the go for heavier parts of most solar applications - he suggests you can go smaller of course for lower current sections of the system (to save $ I suppose - in motorhomes etc. a lot of cable could end up being used).
AnswerID: 307852

Reply By: neil&brenda - Saturday, Jun 07, 2008 at 22:31

Saturday, Jun 07, 2008 at 22:31
Whatever guage wire you use, make sure it has a 20amp plus capacity minimum. You may never get to the ultimate with your panels, but to be sure, to be sure! May sol be with you!
AnswerID: 308436

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