Shelly 2PM Gen4 vs Shelly Plus 1PM

The Shelly Plus 1PM takes the overall win on price and wiring flexibility, since it is cheaper and offers dry and wet contact modes plus DC switching. The Shelly 2PM Gen4 is the more capable module, with two channels, cover mode, Zigbee routing and Matter and HomeKit support.

Channel count and contacts. The Shelly 2PM Gen4 has two 16A channels that can interlock for a shutter motor and can run on Zigbee or Wi-Fi with Matter. The Shelly Plus 1PM has a single channel but supports dry contact isolation and 30V DC loads, which the 2PM Gen4 does not.

Yes. Both the Shelly 2PM Gen4 and the Shelly Plus 1PM list overheating, overvoltage, overcurrent and overpower protection, and both meter power, voltage and consumption. That makes either one a sensible choice for a heater, pump or appliance circuit, provided you have a neutral wire.

Only the Shelly 2PM Gen4. It supports Matter and Apple HomeKit and can join a Zigbee network as a device and a router, in addition to Wi-Fi and Bluetooth. The Shelly Plus 1PM is Wi-Fi only, with Alexa, Google Home, SmartThings and Home Assistant support but no Matter or HomeKit.

Buy the Shelly Plus 1PM if you want to spend less on one protected, metered 16A channel and you need dry contact isolation or DC switching, for example on a boiler, gate or low-voltage circuit. It has a long reliability record and a 3-year warranty.

Buy the Shelly 2PM Gen4 if you need two independent metered channels, a roller shutter with obstacle detection, or the flexibility of running on Zigbee or Wi-Fi with Matter, Apple HomeKit and SmartThings support. It fits a standard back box and needs live and neutral.