Number of MPPT Channels
SpecificationHow many independent maximum power point trackers the inverter has, each able to optimise a separate group of strings at its own voltage and current. More channels allow strings on different roof orientations or with different shading to work without dragging each other down.
One tracker forces every connected string to sit at a single compromise operating point, so a roof with an east face and a west face, or one string partly shaded in the morning, loses energy. Two or more independent trackers let each group find its own optimum. This is the specification that most often decides whether a slightly cheaper inverter is actually suitable for a complex roof. Check the per-channel current and power limits as well as the count — channels are not always symmetrical, and a second channel is sometimes rated for fewer strings than the first.