6.0mm leads

[Wherearewenow]

hi all my solar panel has 4.0mm leads comeing from the panel..can i put 6.0mm leads into the connections down to my victron 100/30 box or do i have to use the same size cable (4.0mm)..thanks

 

[Wherearewenow]

my panel is 300watt.

 

[Two on Tour]

Unless it's a long cable run to your solar charge controller, then the 4mm2 will be fine.

We have 6.8Kw's of solar panels on the roof of our house, and that comes into our hybrid inverter via 4mm2 cable.

 

[Wherearewenow]

Only going 3 meter .only asking as I have 6.0 solar cable.shame to waste it. Thanks

 

[Two on Tour]

Nothing to stop you using your 6mm2 cable other than how you are going to connect the 4mm2 to your 6mm2.
Normally your cabling from your panel will terminate with a MC4 connector and you will struggle to get 6mm2 into MC4 terminal crimp.
The easier way is to connect 4mm2 to the 6mm2 in a junction box.

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[ericroy]

6mm2 would be better than 4mm2, as less voltage would be dropped over the cable run.

 

[Two on Tour]

6mm2 would be better than 4mm2, as less voltage would be dropped over the cable run.

What voltage drop over 3 metres on 4mm2 ?

 

[bobandjanie]

We use 6mm, don't throw it away I will have it. Bob.

 

[Wherearewenow]

Nothing to stop you using your 6mm2 cable other than how you are going to connect the 4mm2 to your 6mm2.

Normally your cabling from your panel will terminate with a MC4 connector and you will struggle to get 6mm2 into MC4 terminal crimp.
The easier way is to connect 4mm2 to the 6mm2 in a junction box.

Can I just change terminals around as they fit into each other(still get red to red and earth to earth) thanks

 

[Two on Tour]

Nothing to stop you using your 6mm2 cable other than how you are going to connect the 4mm2 to your 6mm2.

Can I just change terminals around as they fit into each other(still get red to red and earth to earth) thanks

Yup.

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[Wherearewenow]

Thank you all.its going up .cheers

 

[Raul]

You can crimp mc4’s on 6mm solar cable, then plug into the panel’s mc4. The mc4 take 2.5-4-6mm. You can even get multi contact mc4 that you can squeeze a 10mm but need to peel the double insulator to one, by the grommet.

 

[ericroy]

What voltage drop over 3 metres on 4mm2 ?

Assuming (for the sake of argument) the current being passed is 10A, then the voltage drop for 4mm2 would be around .28 volts. Switching to 6mm2 cable would reduce this to .19 volts. When you are depending on winter sun low in the sky, every little helps - but we are talking less than half of one percent benefit!

(The figures above make some assumptions about the purity of the copper cable being used, so others might come up with slightly different results from their calculations. )

 

[Two on Tour]

Assuming (for the sake of argument) the current being passed is 10A, then the voltage drop for 4mm2 would be around .28 volts. Switching to 6mm2 cable would reduce this to .19 volts. When you are depending on winter sun low in the sky, every little helps - but we are talking less than half of one percent benefit!

(The figures above make some assumptions about the purity of the copper cable being used, so others might come up with slightly different results from their calculations. )

But you are not comparing apples with apples. Solar panels are pushing out 20 plus volts not the 12 volts you are assuming, so even less than the piffling voltage drop you calculate.

 

[Revolvor]

I have two panels with short 4mm2 leads and MC4 connectors going into a Y-splitter and 6mm2 cable from there to the controller.

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[ericroy]

But you are not comparing apples with apples. Solar panels are pushing out 20 plus volts not the 12 volts you are assuming, so even less than the piffling voltage drop you calculate.

An unfounded assumption on your part and then a false argument derived from it. The calculations were based on the 20 volts typical for many panels, so not sure why you imagined it had used 12v? Also, as the voltage increases along the cable, then the voltage drop also gets greater. Otherwise I agree with you completely.....

 

[Raul]

For the sake of the argument, a 4mm2 running 4 meters, 300w at 20v and 30degC will have a 0,617v drop; that’s 3%. In my book that’s loads before the charger, add 2% from the conversion efficiency, and some loss from controller to battery. If you have the wire, use it.

 

[autorouter]

But you are not comparing apples with apples. Solar panels are pushing out 20 plus volts not the 12 volts you are assuming, so even less than the piffling voltage drop you calculate.

The voltage drop along a cable depends only on the amps, not the volts. As ericroy said

Assuming (for the sake of argument) the current being passed is 10A,