More trackers can separate electrically different roof sections
An MPPT controls a connected PV operating group to find its maximum-power point within the tracker’s limits. When roof planes have materially different orientations or irradiance patterns, separate trackers can prevent one operating group from forcing another onto the same voltage/current operating point. A four-MPPT inverter can therefore provide more grouping flexibility than a two-MPPT model—but only when the inputs and strings are actually configured to use that flexibility.
Count trackers, inputs and current limits separately
An inverter can have multiple physical DC inputs that share one tracker. Conversely, a tracker may accept parallel strings subject to its current and short-circuit-current limit. Do not infer four independent MPPTs from four connector pairs. Read the exact datasheet and map each proposed string to its tracker. The MPPT voltage/current checklist helps document those constraints.
Simple roofs may not benefit from extra complexity
A large unshaded roof with strings of the same module type and orientation may work perfectly with two trackers. Additional trackers matter when they solve a real layout constraint, not because four is automatically “better.” Module-level electronics may offer another architecture where shading or roof complexity is severe; compare that separately using optimizer vs microinverter architecture.
Compare usable design freedom rather than the headline count
Check minimum and maximum MPPT voltage, startup voltage, current per tracker, short-circuit limits, maximum strings and any power-sharing rules. Then overlay the actual roof layout. A well-designed two-MPPT system can outperform a poorly grouped four-MPPT design. The right specification is the one that gives each distinct array section a documented operating path inside the inverter’s approved electrical window.