The Shelly EM Gen3 is a tiny Wi-Fi energy meter that tracks one or two circuits, such as an EV charger, heat pump or solar feed, and can signal a contactor when usage gets high. It costs about $70 from Shelly with one 50A clamp in the box.
Wondering how an energy monitor fits with a smart thermostat, EV charger or backup battery? Our Whole-Home Energy Calculator adds up the whole setup: the electricity it adds or saves each month and the net change on your bill.
What it’s good for
Think of it as a meter for specific loads, not a whole-home monitor. Pick the one or two circuits you most want to watch, then build dashboards or alerts around them:
- One or two big loads: EV charger, heat pump, water heater, pool pump or a solar inverter feed
- Load shedding: its relay can switch an external contactor, for example to cut a water heater while the EV charges
- Alerts: in Home Assistant, get a notice when a pool pump runs too long or a load spikes
- Bigger circuits: swap in the optional 80A clamp for loads above 50A
Installation
It’s about 1.5 inches square and mounts on a wall or inside an electrical cabinet, powered from 110 to 240V through its own 2A breaker. That means working in your panel, so hire a licensed electrician.
How it compares
| Shelly EM Gen3 | Emporia Vue 3 | Refoss EM16P | |
|---|---|---|---|
| Typical price | About $70 | $100 to $200 | $160 to $200 |
| Circuit sensors | 2 channels, 1 x 50A clamp included | 16 x 50A | 16 x 60A |
| Mains sensors | None (80A max per channel) | 2 x 200A | 2 x 200A |
| Local, no-cloud mode | Yes: Home Assistant, MQTT | No, cloud app | Yes: web UI, Home Assistant, MQTT |
| Connection | Wi-Fi and Bluetooth | Wi-Fi or Ethernet | 2.4GHz Wi-Fi |
| Warranty | 3 years | 1 year | 2 years |
| Best for | One or two circuits on a budget | Whole home plus 16 circuits in an easy app | Whole home plus 16 circuits, kept local |
See my Emporia Vue 3 and Refoss EM16P reviews.
Want to see other Energy Monitors? Compare them side by side →
How I researched this: Shelly’s US product page and knowledge base specs, Smart Home Explorer’s review roundup, and Home Assistant community reports. Prices checked September 29, 2026.
Shelly EM Gen3
Shelly EM Gen3 review: a $70 two-channel Wi-Fi energy meter with local Home Assistant support and contactor control. What it is good for and alternatives.
Product Brand: Shelly
Product Currency: USD
Product Price: 65
Product In-Stock: InStock
4.6