For most homeowners, buy the Emporia Vue 3. Emporia says its app is free and lists no subscription, and the monitor adds up to 16 circuit sensors to whole-home readings. The catch is that it needs an active internet connection and has no local data storage. Choose the Shelly Pro 3EM V2 if you want a professionally installed meter with LAN connectivity. Buy the P3 Kill A Watt P4400 if the question is only how much one plug-in appliance uses.

Pick Best for Key sourced spec Buy
Emporia Vue 3 Circuit-level detail in most U.S. homes Two 200A main sensors, up to 16 50A circuit sensors; 2.4 GHz Wi-Fi and Ethernet; UL 61010 and UL 2808 Emporia Vue 3 on Amazon
Shelly Pro 3EM V2 Installed meter, LAN and Wi-Fi Amazon listing: 120A v2, Wi-Fi, Matter and LAN Shelly Pro 3EM 120A v2 on Amazon
P3 Kill A Watt P4400 One plug-in appliance, no account 115 VAC, 15A, 1,875 VA; shows kWh, volts, Hz, power factor, amps, watts, VA Kill A Watt P4400 on Amazon

Emporia Vue 3: best overall

The base monitor uses sensors on the incoming service conductors, and the 8- and 16-sensor kits add 50A sensors for individual breakers. That suits an EV charger, water heater, dryer, heat pump or workshop circuit. Emporia lists customizable notifications, solar and net-metering tracking, and UL 61010 and UL 2808 listings. It is installed inside the panel, so hire a licensed electrician. Emporia says readings are typically within about 2 percent of the utility meter but are not revenue-grade, so use the utility bill for billing disputes.

“No subscription” does not mean “no cloud”: real-time monitoring, storage and updates run through Emporia’s servers. If you refuse cloud accounts, look at the Shelly or the Kill A Watt.

Skip it if: you need local-only data, billing-grade measurement, or just one refrigerator’s usage.

Shelly Pro 3EM V2: best for installed local-network use

The Amazon listing for the 120A v2 describes a Wi-Fi, Matter and LAN smart energy meter. Shelly’s product page did not show readable specs when this page was researched, so this page does not claim more than that. Read the maker page for clamp, mounting and integration details first. Plan on professional installation and getting phases and sensors mapped correctly.

Skip it if: you want a guided consumer app with no setup work.

P3 Kill A Watt P4400: best without an account

P3 lists the P4400 as measuring cumulative kWh, voltage, line frequency, power factor, amps, watts and VA on an LCD, rated 115 VAC (125 VAC maximum), 15A and 1,875 VA. Plug it in between the outlet and the appliance and leave it long enough to cover a full cycle, since a short reading can miss a compressor or heater that cycles. The page does not describe any app or subscription. It is not for hardwired or 240V equipment and keeps no remote history. See the Kill A Watt P4400 review .

How to choose

Ask four questions before checkout. Is the core feature free, including charts, exports and alerts? Is a cloud account required? Can you export the data? What still works if the company stops its service? Weigh these against installation cost, because a panel monitor needs an electrician and a plug-in meter does not.

A hypothetical always-on 5 W local controller uses 43.8 kWh a year (5 x 24 x 365 / 1,000). That is an illustration, not a requirement of any monitor here. Check your utility portal first: it may already give interval data for free. A monitor saves nothing by itself; pick one when you have a specific load to investigate and a change to test. For the cloud question, see local versus cloud monitoring .

Sense ended sales of its consumer panel monitor on December 31, 2025, per its support notice, so treat remaining stock as legacy hardware.

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