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Pv string lengths for positive and negative cables


Tariq
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I want to add another 4 panels in series, in landscape mode , can I use,  let’s say 12 meters for the positive cable, and can the negative cable be 4 meters in length

These are 355 watt panels using 4 mm2 solar wire

 

 

 

 

 

Edited by Tariq
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It's a series string and the total length is that of the complete string. The length of the positive wire vs. the negative one does not impact that. 

A 4 mm2 wire has a rating of 48A. Your panels are in series so that should be fine as well.

For the loss over the 16m distance though, you might be better off using 6 mm2, but the 4 mm2 will work just fine ( 0.4V loss more for the 4 mm2 )

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You must figure out how much current you are going to feed trough. One panel bank with panels in series might produce a max current of 9A.

Here the continuous current ratings of various standard wire sections. Note that these are for ambient temperature of up to 25°C. If ambient is higher as might be the case in the roof under the sun you must downgrade. When connecting banks in parallel you must sum up the banks current for the down feed.

1.5 mm²   10A

2.5 mm²   16A

4 mm²      25A

6 mm²      35A

10 mm²    60A

15 mm²    100A

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4 hours ago, Beat said:

Here the continuous current ratings of various standard wire sections. Note that these are for ambient temperature of up to 25°C. If ambient is higher as might be the case in the roof under the sun you must downgrade. When connecting banks in parallel you must sum up the banks current for the down feed.

1.5 mm²   10A   15A

2.5 mm²   16A  25A

4 mm²      25A 30A

6 mm²      35A 40A

10 mm²    60A  50A

15 16 mm²    100A  60A

Hi Beat these figures are not correct at all, please refer to the SANS regulation for  correct figures. 

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  • 1 month later...
On 2020/08/26 at 2:23 AM, Jaco De Jongh said:

Hi Beat these figures are not correct at all, please refer to the SANS regulation for  correct figures. 

Tanks for your remarks. The difference comes from the fact that I relate to the Swiss standards where I graduated el eng. The SANS figures that you corrected to seem to me to high and not save (exept 10 mm² and 16 mm²).

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