I'm using low voltage landscaping cordage. It's the black high-density plastic insulated 12-gauge stranded copper wire marketed for laying out on the ground or direct burial, to run low voltage lighting and water pumps. Run from panel to panel and to sealed plastic splice boxes to do series-parallel 24-volt feeds. From there it's 10-gauge feeder wires hauling 24-volt homeruns to my combiner box.
For running a cable across the yard, and across a short span of rock wall, I'm going to have to armor it; what types will give waterproofing as well as UV protection? they have that flexible spiral wound armor but that doesn't seem waterproof... the other type is the electrical conduit, but that seems like it would be prone to rust quickly (lots of red dirt here, somewhat corrosive to metals).
Any reason I can't use a heavy duty outdoor extension cord to get power from 2-100 watt solar panels to my controller as long as the amps don't exceed the max amps allowed on the ext. cord?