Guda, do you know what the specs of your powerbox batteries are? Looking at the adds, I have the sense they might be two 100AH 12V batteries wired in series for 24V. With those assumptions, I'd say you need to reduce the number of panels. Let me do some math for you, then when you find more accurate values, you can plug them in.
AH capacity x 0.1C x Voltage =Watts. I'm thinking that would work out to be 100AH x 0.1 x24V = 240Watts. Maybe multiply that by a 1.2X fudge factor to get 290W. So, maybe just one panel would be good, assuming my assumptions are correct. First question, will panels be oriented towards the sun, laying flat, on a steep roof, or what?
Now lets say the panels are in an awful orientation, laying flat, so maybe they are only producing 50% of their rated power. Even just two of your panels, laying flat would produce about 265W x 2 x 0.5 = 265W, about what the first formula stated. If the batteries are a LOT bigger, maybe they might handle the current from 3 panels. Unless you know just how big the CIC batteries are, I think you should at first scale back the amount of power you are feeding them.
Two of your panels in series would be putting out ~70VDC, so I don't think you need to focus much attention on wire size. At that voltage, 10 gauge solar wire would be fine, with only about 0.5V drop over a distance of 30 feet.
Is it a good idea to keep the positive and negative wires the same distance?
I have three solar panels wired in series. The negative side is only 1 foot from the junction box but the positive side is 17' from the junction box. Is it best to make both leads the same size(the longest length)? So make the negative 17' as well?
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