Setting up solar panels

[MarkI]

Ah ok, 10 panels - I misread there. So the input side of the inverter (very nice inverter, with built in regulator/charger, BTW) is 48V, meaning you'd need some combination of series/parallel with your panels to get a 48V input to the regulator. So 15m at 48V and a 2400W array equals around 50 amps of current in your wiring. You'd need 13mm2 wiring.

http://www.freesunpower.com/wire_calc.php

http://www.technick.net/public/code/cp_dpage.php?aiocp_dp=guide_awg_to_metric

A basic rule of thumb you can use for DC cabling up to 20m lengths is:
Maximum 4A per 1mm² cable.

I would wire each series string seperately and bring them all together in a combiner box. Before combining each of the strings in parallel put a fuse on each of them so that you can isolate each of the strings seperately for maintenance.
This has a number of advantages:
1. You can do maintenace on each series string seperately and still use the other strings for generating electricity.
2. You only need a very short piece of (13mm2) expensive cabling from the combiner box to the charge controller.
3. Depending on the current generated by each series string, you should only need 4mm2 to 6mm2 cable.

There is however one disadvatage to this setup. You need more cable to connect all your series string to a combiner box.

 

[wm0000]

Switching tracks a little ... since the topic is "Setting up solar panels" ... I'm recabling the house and want to make provision for PV panels to be placed on large flat roof on 2nd floor at some future date. The 12kVA MLT Drives Power Star (with integrated solar regulator) is in the Facilities Room some 15m away. What size conduiting and cabling should I put between the roof/PV panels and the Facilities Room? I forseesee the equivalent of about 10 x 240W panels.

That's pretty close the the system I just installed. To get the current down, I used a Sunny Boy grid-tied inverter with a 400VDC max input so I wired all my panels in series with standard 7/20 house wire in plastic conduit - panel peak current is about 10A @ around 300VDC. Avoiding shading with series panels is very important but the space used is not obstructed by trees or shadows so it's perfect. I generate about 15KWh / day even with this rain we've had in Gauteng which is pretty good. I'm hoping for about 500KWh / month once the sun shines