MPPTs & parallel strings

You’ve got groups (Module 3) sized into strings (Module 4). Now they plug into the inverter’s MPPT inputs. Understanding what an MPPT does — and its current limit — is what lets you connect multiple roof faces without losing energy.

What an MPPT actually does

A solar panel has one “sweet spot” of voltage and current where it makes the most power, and that point drifts all day with sun and temperature. A Maximum Power Point Tracker continuously hunts for it and holds the panels there. Each MPPT optimizes everything connected to it as a single group.

Why each orientation wants its own MPPT

Here’s why Module 3 mattered: if you put a south group and a west group on the same MPPT, the tracker can only pick one operating point for both — and the mismatched group is dragged off its sweet spot. Give each roof face its own MPPT and each is optimized independently. That’s why inverters advertise “2 MPPTs,” “3 MPPTs,” etc. — it’s how many independent groups you can run.

Parallel strings add current

Within one MPPT you can wire several strings in parallel — which, from Module 1, adds their current (voltage stays the same). The catch: the datasheet gives a max input current per MPPT, and your paralleled strings’ combined current (use the panel’s Imp, and check Isc for safety) must stay under it. So an MPPT input is bounded two ways: voltage (Module 4) and current.

Putting strings on inputs

• One roof face → its own MPPT, ideally.
• Multiple strings on the same face → parallel them on one MPPT, staying under the current limit.
• More distinct faces than MPPTs → you’ll either combine compatible ones or step up to a bigger inverter (or add optimizers/microinverters).

Next: sizing the inverter itself — the DC/AC ratio and clipping.