This is how I wire a single string PV array in the combiner box, but it applies to multiple parallel strings as well. In this case, one string for up to 500 VDC.
The PV + and PV- each enter into a DIN rail mounted solar fuse holder. In this case, 20 amps. Then they exit the fuse holders and go into a double pole breaker, rated for 600 VDC and 15 amps. They exit the breaker as follows: The PV+ directed to a DC disconnect switch, one switch pole for every PV+. The PV- exits the breaker to a PV- buss bar. The lightening arrestor (Midnite Solar 600 VDC rated) is attached to the ground buss bar in the combiner box, the PV- buss bar and the PV+ wire before the PV+ is attached to the solar fuse. Leaving the combiner box is a wire from the PV- buss bar, the ground buss bar and the PV+ wire (goes to disconnect switch), then they can go to the inverter. The ground buss bar is connected to the array by bare copper wire bonded to all metal parts of the array, the rails and panels. There is also a ground earth rod too, but this is controversial on this site.
This provides protection to the inverter on the PV+ and PV- sides and 2 points of disconnecting power to the inverter, at the breaker PV+ and PV- and the switch PV+.
If doing parallel array strings, the photo of combiner box one shows lower voltage strings in this case and only the PV+ travels across a single pole breaker. The PV+ line was fused with a solar breaker using a fusible DC disconnect switch. The bottom of the breakers uses a buss bar to connect the PV+ to a single point of exit to the disconnect switch. This method is cheaper, but does not protect the PV- side of the circuit to the charge controller. The PV- does carry current too.