Solar cable

[pessimist]

Am about to install a new solar panel rated at 80w so I guess I'm looking at 4-5 amps at best.

The panel will require a cable run of ~10m to the batteries.

Do I need special solar cable for this installation? The table I found suggests that I would need AWG 11 for this purpose. This apparently equates to 2.5mm or 4mm squared. Plenty of suppliers on fleabay but its not clear whether they are sizing in mm or mm squared.

My brain hurts. Help.

Thanks,

Colin

[VicS]

10 metres distance = total cable run of +ve plus -ve of 20 m

20m = 66 ft

from this table http://www.engineeringtoolbox.com/am...uge-d_730.html

AWG 10 will result in no more than 3% volts drop at 5 amps

AWG 10 is 5.26 mm²

use the next available larger size

[nigelmercier]

Am about to install a new solar panel rated at 80w so I guess I'm looking at 4-5 amps at best... 10m ...

http://www.solar-wind.co.uk/cable-sizing-DC-cables.html

Says 6mm² so agrees with Vic.

[watermint]

my solar panel take volts out of my battreys and probley charg the the sun back up ?

[VicS]

my solar panel take volts out of my battreys and probley charg the the sun back up ?

If its discharging the battery at night it is probably because it does not have a blocking diode.
Solar panels supplied for battery charging usually have diode built in somewhere but it should be stated in the spec.

If its discharging when the sun is shining its either defective or possibly connected the wrong way round (??)

[bedouin]

To be honest the internal resistance of a solar panel is so high that the resistance of the cable connecting it to the battery should not be an overwhelming consideration. So I don't think you need to stick to the 3% drop rule - you should be fine going up to nearer 10%. I think 2 sq mm would be fine for the task.

It is more normal to quote in sq mm than diameter - and you should also be able to tell by the price

[VicS]

To be honest the internal resistance of a solar panel is so high that the resistance of the cable connecting it to the battery should not be an overwhelming consideration. So I don't think you need to stick to the 3% drop rule - you should be fine going up to nearer 10%. I think 2 sq mm would be fine for the task.

It is more normal to quote in sq mm than diameter - and you should also be able to tell by the price

True the panel resistance is high but you dont want to loose 1.2 volts in the wiring.

[pessimist]

Thanks everyone. Do I have to use "solar" cable which appears to be double insulated etc. or can I use any cable of the correct rating?

[VicMallows]

Thanks everyone. Do I have to use "solar" cable which appears to be double insulated etc. or can I use any cable of the correct rating?

Of course you don't need to use 'special' cable ... or 'special' connectors for that matter. (I trust you are not just taking the micky ).

[V1701]

I've used the (4mm) cable and connectors from Midsummer Energy http://midsummerenergy.co.uk/buy/cables_connectors/ satisfactorily for my two solar panels. I've also had some 2.5mm from a supplier off ebay that I've just used to do a partial rewire, not tinned but good quality at £9.99 freepost for 20m. I'd go for something more substantial than 2.5mm for your solar panels, if only from a physical strength point of view if that helps...