Energy-monitoring smart plugs and whole-home energy monitors both show you where electricity goes, but they look at your house from opposite ends. Knowing which end you need saves you from buying the wrong one.
What a smart plug measures
A smart plug measures exactly one thing: whatever is plugged into it. It’s precise for that device, installs in seconds and costs roughly $10 to $40. The limits are just as clear. It can’t see anything hardwired, like your HVAC, water heater, oven, dryer or EV charger, and most plugs are rated for 15 amps at 120 volts.
What a whole-home monitor measures
A panel monitor like the Emporia Vue 3 or Shelly EM Gen3 clamps sensors around the wires in your electrical panel. Depending on the model, it can show total household use and individual circuits, including the big 240-volt loads a plug can’t reach. The tradeoff is installation: it goes inside your panel, and many homeowners hire an electrician for it.
Which to start with
Start with a plug if you have a specific suspect, like an old fridge, a dehumidifier or an entertainment center, or if you rent and can’t touch the panel. Start with a whole-home monitor if your bill is high and you don’t know why, or if you’re planning for solar, a battery or an EV charger and want a baseline for the whole house.
Why they work well together
The two tools answer different questions. A panel monitor tells you a circuit is busier than it should be, and a plug tells you which device on that circuit is responsible. Emporia makes this easy because its smart plug shows up in the same app as the Vue monitor, but any plug works as a follow-up tool once the panel monitor points you at a room.
Want to see how a few smart plugs fit with the rest of your setup? Our Whole-Home Energy Calculator adds up what plugs, a thermostat, an energy monitor, an EV charger and a backup battery would mean for your monthly bill.