Shelly 2PM Gen3 vs Shelly i4 Gen3

The Shelly 2PM Gen3 wins overall. It switches two independent 16A circuits, measures consumption per channel, offers interlock mode for shutters and blinds, and is better rated by owners. The Shelly i4 Gen3 is cheaper but is an input module with no relay and no metering.

Relay channels. The Shelly 2PM Gen3 has two, complete with interlock mode so they can safely drive a motor up and down, plus per-channel power measurement. The Shelly i4 Gen3 has zero relay channels and four inputs instead, so it can only trigger automations.

The Shelly 2PM Gen3, because its interlock mode is designed exactly for that: two channels that can never be energized at the same time, which is what a shutter, blind or gate motor requires. The Shelly i4 Gen3 could read the wall buttons controlling it, but it cannot move the motor.

Yes. Both the Shelly 2PM Gen3 and the Shelly i4 Gen3 support Matter and Apple HomeKit, along with Alexa, Google Home and Home Assistant. Neither supports Zigbee, Z-Wave or Thread, and both are limited to 2.4GHz Wi-Fi with Bluetooth for pairing and gateway duties.

Buy the Shelly 2PM Gen3 if you need to control two circuits from one module or automate a roller shutter, blind or garage door, and you want to see how much each channel consumes. It fits a standard back box and needs live and neutral at the install point.

Buy the Shelly i4 Gen3 if your goal is to reuse existing wall switches, buttons or dry-contact sensors as triggers for scenes and automations. It is cheap, compact and reliable, works as a Bluetooth gateway, and is designed to sit alongside relay modules rather than replace them.