What is MPPT, and why does it matter for solar?

Every solar panel has one combination of voltage and current at which it produces the most power. That's its maximum power point. The trouble is that the point keeps moving as light, temperature and shading change through the day.

Maximum Power Point Tracking (MPPT) is the electronics that keep finding it.

What MPPT does

An MPPT controller continuously adjusts the electrical load on the panels. It nudges the operating voltage up and down, watches what happens to the power, and settles where the power is highest. As a cloud passes or the panels warm up, it moves with the change.

Every grid-tied inverter has MPPT built in. The question is what it's tracking: a whole string, or each panel.

String-level vs panel-level MPPT

• String-level MPPT (in the inverter) finds the best operating point for the string as a whole. If every panel is identical and evenly lit, that's also the best point for each panel.
• Panel-level MPPT (in an optimiser behind each panel) finds the best point for each panel individually.

On a perfect, unshaded roof the two give much the same result. On a real UK roof, with a chimney shadow in the morning, an east/west split or one panel that's dirtier than the rest, the panels' best points diverge. String-level MPPT has to compromise. Panel-level MPPT doesn't.

Why it matters

• More energy on difficult roofs. Shaded, split and mismatched panels each give what they can, without holding back the others.
• Better data. Because each optimiser knows its own panel's operating point, it can report it, so you can see each panel's performance.
• Simpler design on awkward roofs. You can mix orientations on a string more freely, within the inverter's limits.

MPPT in the Archai system

Each Archai iOPT 800W optimiser tracks its panel's maximum power point across a 12–60 V range, with a peak MPPT efficiency of ≥ 99.7%. It clips to the module frame behind the panel and sends its data down the DC cable to the Archai GT gateway (power line communication, so no Wi-Fi on the roof), and from there to SolarSync.

Read more about how optimisers work, see the Archai system, or talk to us.