Solar Wire Size..??? Fuses on panels...??

I'd go with no less than #4. You said the wire run was easy. Make it even easier with #4 welding cable. You'll be under 3% loss and out around $100. Guys that are recommending #10 and 12 wire are not getting maximum potential out of their systems. Yes, they work but could work better with bigger wire. my last system had 3- 135 watt 12 V parallel panels with #4 welding cable. My new system is getting 2-250 watt 24 V panels in parallel with # 6 Welding cable at 30 feet. If my controller would take the voltage, I'd wire them in series to be able to use smaller wire. A fuse is not necessary, in my opinion, but they are handy as a convenient disconnect. I do not know if they are required by any code.