Do you want a code compliant (NEC) install??
If you mount on trackers, (not on the structure itself) you are not required to install a ground fault interrupter. It is a good idea regardless however. Lightning protection is also a good idea, but not required by NEC (yet).
Your battery fuse should be located AT THE BATTERY TERMINAL and sized for 125% of the max inverter current draw based on the inverter nameplate rating. All your wire used must be sized for an ampacity of 25% greater than the max rating of the device you are connecting it to (unless its a dump load- then it must be sized for 50% greater current). You should have a DC or battery disconnect before the inverter (usually fused) for 125% of the inverters rating.
You should have a disconnecting means before and after the charge controller. The charge controller should be fused for 125% of its rated output regardless of PV array sizing.
The wire used on the PV array should be sized appropriately for the short circuit current of the string it connects. It must then be de-rated for temperature (even if you use 90 C wire). Most common wire used is XLPE/USE 2. It is sunlight resistant. It then must also be de-rated for continuous duty (over 3 hours use). This is the common 1.56 (25% x 25%) multiplier commonly used to size PV equipment.
If you have more than three PV source circuits, you must have a fusible disconnect (each string fused) to avoid any back feeding of any SINGLE string. After ALL these things are met, the wire then must be sized to accommodate less than a 2% voltage drop (usually). You will end up with wiring that will exceed the NEC calculations for current in the end because of the voltage drop issue.
Most commonly available battery cable (usually) does not meet NEC requirements. Its up to you if you want to use it of not. Is your system being inspected? Probably not if its off grid.
All equipment must be bonded. Module frames, rails and tracking equipment. Run bonding wire back to the house with the DC cables. Make the termination inside the 125 Amp service panel. Bring all other bonding wires to this point. Inverter bonding wire, battery negative terminal bonding wire, charge controller ground wire and any other equipment grounding conductor you may have. Then run a grounding conductor to earth from this point. It is up to you if you want to add an extra grounding electrode at the array. Usually if this is done, it is connected to the house grounding electrode with a bare solid conductor buried underground. This eliminated the possibility of your equipment seeing more than one path to earth and eliminated any ground loops you may have.
All of this info can be found in the NEC book and under article 690 (PV systems).
I am by no means an expert. This is just what I have to deal with all the time as I do this professionally.
Hope I didnt scare you.