What is a microinverter?

A microinverter is a small inverter mounted under each solar module that converts that panel's DC into AC on the spot. Instead of sending high-voltage DC down to one central inverter, a microinverter system carries AC across the roof from the first module. Here is how it works and where it fits.

Module-level AC conversion

In a microinverter system, every module has its own inverter attached to the racking beneath it. Each one:

• Converts the module's DC to 240 V (split-phase) AC.
• Runs its own maximum power point tracking (MPPT), optimizing that single module independently.
• Connects to the next microinverter along a shared AC trunk cable.

The trunk feeds a combiner or subpanel and then the service. Because conversion happens at the panel, there is no high-voltage DC conductor running through the building.

Why it satisfies rapid shutdown

NEC 690.12 effectively requires module-level rapid shutdown on rooftops in the 2020 and 2023 editions. Microinverters meet this by design: when AC is removed, each microinverter stops, and the only DC in the system is the short run inside the module-to-microinverter connection, already within the controlled region.

That means no separate PVRSS device is needed. For the full rule, see NEC 690.12 rapid shutdown explained.

Pros

• Shade tolerance — each module has its own MPPT, so a shaded panel only loses its own output instead of dragging down a whole string. See shading and solar production.
• Per-module monitoring — you can see each panel's production and spot a failing module.
• Simple expansion — adding modules is straightforward because each is independent.
• No high-voltage rooftop DC — the array wiring is AC.

Cons

• Cost per watt — one inverter per module usually costs more than a single string inverter.
• More rooftop electronics — more devices exposed to heat and weather means more potential failure points, though units are individually replaceable.
• Battery pairing — microinverter systems typically use AC-coupled storage, which can be less efficient than DC-coupled options on some hybrid inverters.

Where microinverters fit best

They shine on complex roofs — multiple planes, dormers, chimneys, and partial shade — where module-level MPPT recovers real energy and where per-module monitoring is valuable. On a large, unshaded, single-plane roof, a string inverter may win on cost. The full comparison lives in microinverters vs string vs optimizers.

On the plan set

Whichever you choose, the one-line diagram must show the device, the AC trunk and conductors, overcurrent protection, and the rapid-shutdown label. A microinverter system still needs correct AC conductor and OCPD sizing to the point of connection.

Microinverters trade higher per-watt cost for built-in shutdown, shade tolerance, and granular monitoring. Confirm every spec against the datasheet, and have a licensed electrician or PE review the final design. Ready to lay one out? Start with the DIY workflow.

Educational reference, reviewed 2026-07. A design aid, not a substitute for a licensed electrician or PE. Confirm the enforced NEC edition and local amendments with your AHJ.