It means the solar array can be divided into two independently tracked sections instead of forcing both strings to operate at one shared maximum-power point. That can help when roof orientation, shading or string layout differs between two PV groups. The ABP product data lists a maximum open-circuit voltage of 550Vdc + 550Vdc across the two inputs. For an off grid solar inverter, string voltage and current still need to be calculated from the selected modules and site temperature.
