Cable rating for solar panel to controller

[timhowes]

My 100W PV panel was supplied with 5m of cable, 1.25 square millimetres. It has come up a couple of metres short as I have chosen to install my 10A MPPT controller under the glove box in the passenger footwell.

As a total novice, I unsurprisingly have a few questions!

1. Given I have 100w panel and 12v battery, this sounds like 8.3A. I've got some 17.5A cable lengths I can complete the cable run with, not sure what the cross-sectional area is though. +ve and -ve will each need to be about 2m long, making a total of 7m cable run from panel to controller. Is the 17.5A rated cable I've got okay to do the 2m extensions, or might it catch fire?!

2. In terms of efficiency, is my chosen setup (long 7m course from panel to controller, short 1.5m course from controller to leisure battery) less good than having the reverse, i.e. short course from panel to controller and longer course from controller to battery? If so I could find somewhere further back to stash the controller.

3. Will the 20A fuse I'm putting by the +ve terminal of my leisure battery be sufficient?

Thanks for any wisdom offered, of which there seems to be plenty around!

Tim

[g8dhe]

No your fine with all the assumptions you have made. The reason for using much larger cables is simply that your trying to minimise voltage drop. Fuses should be rated for the cable that they are supplying so 15 Amp would be better than 20 Amp, your not going to be exceeding the current draw/charge for the battery so that's fine.

[timhowes]

Brill, thanks I knew you'd come through for me!