Shelly i4 Gen3 vs Shelly Plus 1PM

The Shelly Plus 1PM wins overall. It has a 16A relay with energy monitoring, dry and wet contact modes and a full protection set, plus a 3-year warranty. The Shelly i4 Gen3 is cheaper and supports Matter and Apple HomeKit, but it has no relay and no metering.

Switching and measuring. The Shelly Plus 1PM controls a circuit and reports exactly what it consumes, with protections against overheating, overvoltage, overcurrent and overpower. The Shelly i4 Gen3 has four inputs and no relay, so it can only trigger automations that other devices act on.

The Shelly Plus 1PM. It measures instantaneous power, voltage, current and accumulated consumption on the circuit it switches, which makes it popular on water heaters, pumps and appliances. The Shelly i4 Gen3 has no metering hardware at all.

Only the Shelly i4 Gen3, which supports Matter and Apple HomeKit alongside Alexa, Google Home and Home Assistant. The Shelly Plus 1PM works with Alexa, Google Home, SmartThings and Home Assistant, but has no Matter or HomeKit support.

Buy the Shelly Plus 1PM if you want to switch a 16A circuit, see its consumption and have overheating, overvoltage, overcurrent and overpower protection watching it. Dry contact mode also lets it drive a boiler or gate input, and it runs fully locally with Home Assistant.

Buy the Shelly i4 Gen3 if you want four inputs to read existing wall switches, buttons or dry-contact sensors and fire scenes from them, with Matter and Apple HomeKit support. It is cheap and compact, and it pairs naturally with a relay module that does the switching.