Thanks guys,
I was thinking that multistrand would be the obvious choice over solid. Something I don't know here?
Copper of course. I was going to try to use the heaviest gauge that is managable.
If things go as planned I should have about an 8 foot run from panel to CC. And about 2 feet from CC to Batteries.
Makes me think. Fuse in the Pos. line from CC to Batt? What size and type?
One panel to start (100W). Will add another 100W later with about a 4 foot run wired in series.

take the isc x1.5 and round up the the nearest common value. 4.88x1.5=7.32 round up to 10a. any standard type fuses will do, just be sure they aren't slo-blow or fast blow types. either #12 or #10 will work just fine. #12 will have about voltage drop percentage of 1.4% and #10 about .88% for the specified lengths of wire runs. #12 stranded is very common for speakers too, but be carefull if the polarities aren't marked on the wire that you don't get the polarity wrong in making your connections.

I'd think it's better then speaker cable. Low voltage landscape wire has a really tough insulation, and it's made for long strings of incandescent bulbs, gauge for gauge, it's likely much better than PVC speaker wire, that gets sticky and oozes after a couple of years. Common sizes are 16, 14, 12, 10 ga.

But then there is the "Premium" speaker wire, with 25,000 psi-pre-attached gold plate lugs, and 14/200 single crystal, oxygen free copper strands, at $18 per inch. Made my iPod sound so much better... (but my earphones keep sliding down now)