What Is a Microinverter? How Solar Panels Make Household Power

Solar panels make direct current; your home and the grid run on alternating current. An inverter converts one into the other, and a microinverter is a small one that serves a single panel, as the Department of Energy’s inverter basics puts it: “Microinverters are smaller inverters placed on every panel.” A string inverter, by contrast, connects a set of panels to one box.

Why do plug-in kits use microinverters?

In a plug-in kit, the microinverter is the part that turns the panels’ output into household power and feeds it into your circuit, as the California Assembly’s analysis of SB 868 describes. Because each panel has its own, shade or damage on one panel doesn’t affect what the others produce, the DOE notes, though microinverters can cost more.

What happens during an outage?

Grid-connected inverters watch the grid. If a disruption is long or larger than normal, the DOE says, they disconnect and shut down. That’s what keeps a plug-in system from feeding lines that utility crews expect to be dead; see backfeed. A microinverter certified on its own is still only a part: laws like California’s ask for the whole kit to be certified, as our UL 3700 guide explains.