Solar cable

pessimist

pessimist

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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
 
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
 
watermint said:
my solar panel take volts out of my battreys and probley charg the the sun back up ?
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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 said:
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
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True the panel resistance is high but you dont want to loose 1.2 volts in the wiring.
 
pessimist said:
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?
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You'd use twin flex surely unless you were running single wires in some form of conduit or trunking.
 
I've used the (4mm) cable and connectors from Midsummer Energy here 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...
 
an 80 watt panel at full chat will poke out about 7 amps which is bit more than your 4-5 amps.

Better a thicker cable to keep loses to a minimum. You may have luck with Ebay and cables for electric winches and similar which are offered at 10 metre lots If the cables is offered with word "solar" in it - double the price!
 
Max solar panel current

pappaecho said:
an 80 watt panel at full chat will poke out about 7 amps which is bit more than your 4-5 amps.

As said 4 amps perhaps a little more is all you will get out of a 80w panel regardless of 12v or 6v battery.
The power rating of a solar panel is generally max current times max voltage and even at max power point it will not give real 80w. good luck olewill
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William_H said:
The power rating of a solar panel is generally max current times max voltage and even at max power point it will not give real 80w...
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If this were true, then it would be (as my father-in-law used to say) a wangle! I'm pretty sure that the quoted power is at the maximum power point, and equals the area of the largest rectangle that will fit under the V:C curve.
 
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its simple, look at the cable you are connecting to, and use the same to the battery, or just ask the supplier for the recommended cable which he will happily supply.

Lots of people do this. I have even had professional installers tell me there is no point going to a bigger wire because "no more electricity can get out" :)
It is much better to size the cable properly with the sort of calculations that have already been posted. Even if the wires exiting the panel are small the voltage drop over a short distance will be small, but if the same sized cable is extended a long way, the voltage loss can be considerable.
 
VicMallows said:
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 :().
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Does this mean that you can use an ordinary electrial block connector to join the cables from two solar panels (20watt each) together and then to a single cable to the regulator?
 
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