Quick verdict
The smallest Z-Wave relay Shelly makes, and it includes power monitoring. Fits behind existing switches in tight boxes, reports energy usage per circuit, and runs entirely local through Z-Wave JS in Home Assistant. You need a Z-Wave controller, but if you already have one, this is one of the best compact relay options available.
Standout: Ultra-compact Z-Wave relay with power monitoring that fits behind almost any existing switch.
Last checked: 2026-03-22