Why is solar panel cable so expensive ?

[dunkelly]

Why is solar panel cable so expensive relative to normal cable ? Is it the covering to stop degradation . My set up will only be set up and used when on anchorage or when not plugged in to shore power so do I need to use it ?

 

[VicS]

Why is solar panel cable so expensive relative to normal cable ? Is it the covering to stop degradation . My set up will only be set up and used when on anchorage or when not plugged in to shore power so do I need to use it ?

Is it ?
have you compared the prices at somewhere like 12 volt planet

Single Core Photovoltaic Solar Cable - 4mm² . . . . . £1.15/m

Oceanflex Single Core Tinned Thin Wall Cable - 4.0mm² . . . . . £1.82/m

and the PV cable has much thicker insulation and is UV resistant

Am I missing something ?

 

[dunkelly]

Thanks Vic , hadn't looked at them , much better , but do you think I need it ? I've got lots of ordinary 3MMS cable and wondered what I'd lose if I used that ?

 

[RobbieW]

Voltage, potentially It depends how long the run is from panel to controller and what nominal voltage you expect from the panel configuration. It's the volt drop from an undersize cable that is the risk

 

[dunkelly]

Thanks , over about 3 metres would it be significant ?

 

[VicS]

Thanks Vic , hadn't looked at them , much better , but do you think I need it ? I've got lots of ordinary 3MMS cable and wondered what I'd lose if I used that ?

Probably not.
As RobbieW says you need to size the cable crossectional area according to anticipated current and length to keep voltage loss within acceptable limits. Subject to to this ordinary twin flex will probably be suitable and more convenient.

 

[VicS]

Thanks , over about 3 metres would it be significant ?

Depends on the current

 

[VicS]

Depends on the current

For a cable run length of 3m ( ie total positve plus negative of 6m) 7 amps would be about the limit before exceeding a 2% volts drop

 

[Alex_Blackwood]

Thanks Vic , hadn't looked at them , much better , but do you think I need it ? I've got lots of ordinary 3MMS cable and wondered what I'd lose if I used that ?

Suspect that it is either 2.5 mm CSA or 4mm. Haven't come across 3mm CSA? will make a difference for Volt Drop.

 

[VicS]

Suspect that it is either 2.5 mm CSA or 4mm. Haven't come across 3mm CSA? will make a difference for Volt Drop.

Avaialbe as single core ( untinned ) from 12volt planet and Furneaux Riddall, but we dont know the pow of the OP's solar array.

 

[RobbieW]

Heres a useful calculator - Voltage Drop Calculator | 12 Volt Planet

Whether the difference matters will depend largely on your expectations. When I put solar on the boat I was a liveaboad and wanted the max charge out of the system and built accordingly. That was with 2x50 in series paralleled with another 2x50 then about 15 metres round trip to the controller. Panels output c. 18v in // and c. 36v for 2 in series, you then need to know the capacities of the controller.

 

[Alex_Blackwood]

Avaialbe as single core ( untinned ) from 12volt planet and Furneaux Riddall, but we dont know the pow of the OP's solar array.

Every day is a school day!!

 

[dunkelly]

Single 50 watt panel , yes I think the cable was from furnaux riddel . Thanks for the calculator . A great help . Cheers guys ,
Ps am I right to fuse the positive from the controller to the battery - 10 amp fuse sufficient ?

 

[noelex]

The two major differences are the permitted maximum voltage and the UV protection.

Note for the two cables linked for sale by 12v Planet one has a maximum voltage of 60v whereas the solar cable is 1500v. The solar cable also has a “UV resistant sheath” which is absent in the “ordinary” cable.

Some even small voltage arrays are over 60v, especially if the panels are wired in series. Ours are wired to an individual controller, but each panel has a Voc of 67v, This high voltage will not be a factor for a single 50w panel, but is worth mentioning for others that may come across this thread.

 

[PaulRainbow]

For a cable run length of 3m ( ie total positve plus negative of 6m) 7 amps would be about the limit before exceeding a 2% volts drop

3m of 3mm sq cable @20v would be 2% at 11a.

Looks like you did the calculation for 12v, it'll actually be about 20v from a 50w panel to the controller.

 

[PaulRainbow]

Single 50 watt panel , yes I think the cable was from furnaux riddel . Thanks for the calculator . A great help . Cheers guys ,
Ps am I right to fuse the positive from the controller to the battery - 10 amp fuse sufficient ?

Your 3mm sq cable will be fine @3m.

You need to fuse the positive from the controller to the battery, as close to the battery as you can. A 5a blade fuse will be fine.

 

[dunkelly]

Thanks guys , something' I'm still confused about is that I note that some people have significantly higher voltage panels , how does that work with 12volt batteries or am I missing something? Is there an advantage to going higher voltage ?

 

[noelex]

Thanks guys , something' I'm still confused about is that I note that some people have significantly higher voltage panels , how does that work with 12volt batteries or am I missing something? Is there an advantage to going higher voltage ?

An MPPT controller will convert the voltage to be appropriate for the battery bank. Even “12v “ panels perform best at voltages above battery voltage.

There are some pros and cons but no big advantage to high voltage panels. However, for larger panel sizes very few 12v panels are produced.

 

[dunkelly]

Thank , always wondered about that .

 

[PaulRainbow]

Thanks guys , something' I'm still confused about is that I note that some people have significantly higher voltage panels , how does that work with 12volt batteries or am I missing something? Is there an advantage to going higher voltage ?

Your 50w panel will be about 20v, the controller will adjust that to be suitable for your 12v batteries.