Solar - Cable type and size

[fer]

Hi,

Getting ready for the summer and looks like it's time to get a solar panel for the boat.

After reading other threads (thanks for all the useful information) I have a pretty good idea of what I need, but I have no clue about cable size and type.

The idea is to mount the panel flat at the front of the boat; this is the only available area. Panel will be about 12m away from the mppt controller and will need 24m of cable, which will run inside the boat between the insulation (polystyrene) and the ceiling wood panels.

So.. What type and size of cable should I get? I guess the idea is that it should be safe, don't get too hot and minimise voltage drop.

Should I use some kind of cable casing to keep the cable away from the insulation and wood panels?

Panel specs are:

Nominal Voltage, Vmp: 54.7

Nominal Current, Imp: 5.98

Thanks in advance.

[spadefoot]

Hi, I would have thought that 6sq mm would be adequate for that run, anything fatter and you might have problems connecting to the mppt. Standard multicore vehicle cable would be fine for inside the boat, maybe some UV protected cable for the bit that's outside. If you're going to run it near polystyrene then put it in some kind of conduit. You will probably need something fatter between mppt and batteries, perhaps 10sq mm or more depending on length of run, this is because the output from the mppt will be many more amps than the input to the mppt.

[spadefoot]

Sorry, I mean multistrand cable not multicore.

[fer]

Perfect, thank you.

I was doing some reading this weekend, and as you say, one core multistranded seems the way to go.

As for size, I couldn't make my mind. Voltage drop doesn't seem that important with 54V from the panel, but didn't know what size was acceptable heat wise. I will go for the 6sq mm as you suggested and put it into a corrugated pipe.

I'm ordering some parts from bimblesolar and I saw they sell a double insulated, UV protected cable. I most likely will use this cable to connect the panel to the controller to avoid having to join different cables. Controller will be pretty close to the batteries and hopefully 10sq mm will be ok, but will check in the chandlers when I buy this one.

Thanks again.

Can't wait to have it all up and get out of the marina

[bastion]

Was at Bimble this morning to pick up a panel and fittings and they advised that 6mm cable was fine for my 10mt run and also for the MPPT to batteries connection.