Quick Summary (TL;DR)
Best for a local-first Home Assistant setup: a Shelly Pro 3EM for three-phase or multi-channel mains monitoring, or a Shelly EM Gen3 for two measurements on one phase. Home Assistant’s built-in Shelly integration communicates directly with compatible devices on your network, without requiring Shelly Cloud. Best for seeing many individual circuits in one consumer system: the Emporia Vue 3, where it is officially sold and electrically suitable; expect cloud dependence, not a native local data API. Best for wired, vendor-independent metering: a properly specified Modbus electricity meterAliExpress price such as an appropriate Eastron SDM-series model, paired with an RS-485 or network interface and configured in Home Assistant.
Do not choose solely by the advertised number of clamps. Confirm your country, mains arrangement, meter variant, permitted CT capacity, import/export reporting, local API availability and all-in installed cost. The wrong phase configuration or a cloud-dependent monitor can be a bigger problem than the upfront price.
Which energy monitor should you buy?
For a smart home, the most useful energy monitor is one that consistently exposes correctly signed power and cumulative energy readings for the electrical boundary you care about. Home Assistant can then calculate consumption, grid imports, exports and costs from meaningful data. Having an app with attractive charts is not the same as owning a reliable Home Assistant data source.
| Priority | Our starting point | Why it fits | Most important caveat |
|---|---|---|---|
| Local, straightforward Home Assistant integration | Shelly Pro 3EM (three-phase) or EM Gen3 (single-phase) | Supported native Shelly integration; local device communication | Limited channels versus a whole-panel circuit kit; model and CT variant matter |
| Many branch circuits and appliance-level visibility | Emporia Vue 3 | Up to 16 branch CT inputs plus main-line sensing per device | Cloud-based data and model/region compatibility; third-party HA integration is not equivalent to an official local API |
| Industrial-style local wired link | Modbus RTU/TCP meter, e.g. suitable Eastron SDM | Registers read locally over RS-485 or Ethernet gateway | Correct register map, wiring, scaling and device variant are your responsibility |
| Single-phase house with grid and solar feed | Shelly EM Gen3, where both CT locations use the supported phase arrangement | Two CT measurements allow separate circuits or feed points | These are not a substitute for independent three-phase voltage measurement |
| Three-phase supply with export and EV charging | Shelly Pro 3EM or appropriate three-phase Modbus meter | Per-phase metering and import/export-oriented measurements | Professional installation, phase mapping and suitable capacity required |
Bottom line: I would prioritise the Shelly route for most local-first Home Assistant buyers, Emporia for compatible households that primarily want extensive consumer-friendly circuit analytics, and Modbus for installers or hobbyists who value a wired interface and can commission it correctly.
What we are comparing—and what we are not
Shelly is a manufacturer and product family; the Shelly Pro 3EM 120A v2 is a DIN-rail, three-phase-capable product shipped with three 120 A current transformers, while Shelly EM Gen3 is a two-channel single-phase product. Do not conflate those models with older Shelly EM, Shelly 3EM, newer compact 3EM-63 models, or relay devices that happen to report power.
Emporia refers here to the Vue 3 ecosystem, not a generic USB-to-CT device or an earlier Vue generation. Emporia states that its Vue monitoring devices transmit measurement data via its cloud and do not have a local device API. The regional electrical specification, orderable kit and warranty must be verified for the intended country before purchase.
Modbus is a communications protocol, not a product quality grade. A Modbus meter could be a direct-connected single-phase DIN-rail meter, a three-phase meter, or a CT-operated instrument. The meter’s hardware determines measurement accuracy, phases and input capacity; Modbus determines how registers are read. An ESP32AliExpress price or Ethernet gateway can bridge the connection, but does not automatically make the meter accurate or compliant.
Feature comparison: Shelly vs Emporia Vue vs Modbus
| Feature | Shelly Pro 3EM 120A v2 | Shelly EM Gen3 | Emporia Vue 3 | Modbus meter |
|---|---|---|---|---|
| Typical role | Main supply, three-phase and PV flow monitoring | Two measuring points on one phase | Whole panel and many branch circuits | Single or three-phase electrical metering |
| CT inputs | Three supplied 120 A CTs; optional neutral CT on specified versions | Up to two compatible CTs; one 50 A clamp in listed base pack | Up to three main sensors and 16 branch sensors per Vue, per vendor | None on direct-connected meters; CT-operated variants vary |
| Phase arrangement | Single or three phase | Single phase | Depends on the exact kit, wiring system and regional approval | Must choose a matched meter variant |
| Home Assistant data path | Native Shelly integration over LAN/Wi-Fi | Native Shelly integration over Wi-Fi | Community/custom integration options use vendor cloud | Home Assistant Modbus or dedicated device integration over local serial/network path |
| Offline from internet | Local HA communication possible if local network is operating | Local HA communication possible if local network is operating | No direct local API; cloud data delivery unavailable until reconnection | Local polling possible if meter and gateway remain powered |
| Network medium | Ethernet and Wi-Fi on stated variant | Wi-Fi | Cloud-connected network link; check exact regional device variant | Usually RS-485/Modbus RTU or Modbus TCP gateway |
| Setup difficulty | Moderate; professional board work | Moderate; professional board work | Moderate/high in crowded panels; many sensors | Highest for DIY HA registers/serial integration |
| Long-term flexibility | Good for LAN automations | Good for LAN automations | Dependent on vendor ecosystem/cloud path | Potentially excellent when documented registers remain accessible |
Specifications are manufacturer-reported and model-specific, not measurements from a hands-on test. Availability and bundled CT counts vary by region and kit. Verify the current manufacturer’s installation manual rather than assuming a seller’s product headline describes every variant.
Shelly: strongest option for a local-first Home Assistant installation
Shelly Pro 3EM: a sensible three-phase default
The Pro 3EM v2 has a documented three-phase monitoring design, a DIN-rail enclosure, three supplied 120 A CTs on the specified variant, wired Ethernet alongside Wi-Fi, and local MQTT/HTTP/WebSocket capabilities. Shelly states up to 1% active energy measurement accuracy under its specified conditions; that is a manufacturer specification, not a claim that every real installation will achieve billing-meter equivalence. It also exposes per-phase active/apparent measurements and cumulative energy.
For a European three-phase house with an EV charger and possible solar export, the Pro 3EM is a clearer fit than trying to reconstruct whole-home readings from two single-phase clamps. Ethernet is attractive in a metal distribution board where radio reception can be unreliable, provided the network cabling, separation and cabinet arrangements comply with local installation requirements.
The meter itself is not a switching relay; switching large loads requires appropriate separate switching hardware and engineering. Its high-current CTs are not interchangeable with arbitrary third-party CTs. A neutral CT is an optional accessory on relevant models and is not necessarily present in the box. The manufacturer documents local logs, but on-device retention is finite; use Home Assistant’s recorder/statistics or another persistent system for longer history.
Shelly EM Gen3: two measurement points, not a three-phase meter
The EM Gen3 can monitor up to two CT inputs on a single phase and supports local integrations via Wi-Fi. Shelly’s current base offering specifies a 50 A clamp, with supported compatible CT options including 80 A on the manufacturer’s page. The model can be a cost-effective choice for a single-phase supply where you want mains consumption and an additional circuit or production feeder, provided the electrical topology and CT placement support meaningful independent readings.
However, two CTs do not make it a two-phase meter. If your home has L1/L2/L3, choose a purpose-built three-phase meter with the necessary phase-voltage information. Also check which Shelly EM generation you are actually buying: the older EM and the EM Gen3 differ in firmware and features, and product listings may not make the distinction obvious.
Does Shelly need the internet?
No external cloud account is required for the supported local Shelly integration to exchange data when Home Assistant and the meter share a functioning local network. The Home Assistant Shelly integration is classified as local push and states that cloud connectivity is unnecessary for device communication. This does not make the whole system immune to power failures, Wi-Fi coverage problems, misconfigured VLANs or router outages. Give the meter a stable local address and verify reachability from the Home Assistant host.
Emporia Vue 3: the circuit-by-circuit specialist—with a cloud trade-off
The principal appeal of the Vue 3 is its panel-wide view. Emporia’s documentation says each Vue can monitor up to 16 branch circuits and up to three main lines, with its software offering combined and nested Vue arrangements for installations needing more visibility. For someone investigating an unexpectedly large electricity bill or differentiating HVAC, EV charging, cooker and dryer usage, that circuit count is genuinely useful.
But it is not the same purchasing proposition as a local-first Shelly device. Emporia explicitly states that Vue Gen 1/2/3 devices have no direct local data API: measurements pass through the Emporia cloud. Its support documentation says short offline periods are buffered, while longer outages result in coarser historical data. A community-maintained Home Assistant integration may provide cloud-derived sensor data, but it should not be described as an official, locally independent integration. Confirm its current repository status and authentication method before depending on it for critical automations.
Emporia’s shop lists a Vue 3 with 16 sensors, but that does not prove the device is approved or electrically compatible everywhere. This matters particularly to UK and EU readers: a North American two-leg split-phase panel is not interchangeable with a European 230/400 V three-phase installation. Do not import a kit on the assumption that frequency, voltage rating, conductor access, certifications and warranty will match your supply. If the manufacturer cannot confirm suitability for your country and panel, choose another product.
Emporia is compelling when you want a polished multi-circuit monitoring ecosystem and accept its cloud architecture. It is less suitable for a local-only Home Assistant network, internet-isolated installation or fast load-management decision that must continue without vendor services.
Modbus meters: less convenient, more explicit control over your data path
A properly specified Modbus meter is a strong option when you want a persistent wired monitoring link rather than cloud telemetry. For example, Eastron’s SDM630AliExpress price Modbus family offers three-phase electrical measurements with RS-485 on relevant versions. Other SDM models target single-phase circuits. Select the exact model for direct connection versus CT operation, current rating, import/export registers, installation standard and phase topology; a family name alone is insufficient.
Home Assistant’s Modbus integration supports direct serial/RS-485 access, Modbus TCP and gateway configurations. If a meter exposes an RS-485 RTU interface, the host needs an appropriate USB–RS-485 adapter or a correctly configured network bridge. An ESP32AliExpress price running a supported ESPHome serial-proxy or meter-specific component may be another approach, but availability and support depend on software version and hardware implementation.
The engineering detail is in the register map. You must establish unit ID, serial settings, register address base, input-versus-holding register type, scaling, signedness, word order and whether energy registers are cumulative. Eastron’s official SDM630AliExpress price protocol document, for example, describes 32-bit floating-point values spanning two 16-bit registers. Copying somebody else’s YAML without checking the exact meter firmware can silently produce nonsense readings.
Do not confuse a direct-connected DIN-rail meter with a non-invasive CT kit. Direct-connected units place the meter in the electrical circuit, whereas CT-operated meters use compatible CTs and separate voltage references. Both require appropriate qualified installation. A Modbus interface is not an accuracy certification, and an RS-485 gateway does not protect against electrical installation errors.
Single-phase, three-phase, solar and import/export: choose the right topology first
A single-phase home
For one incoming live conductor and neutral, one correctly positioned whole-home sensor may be enough to measure net grid exchange. A second correctly configured measurement point can help isolate the solar inverter output or a substantial circuit. If you want branch-level appliance attribution across ten or more circuits, a circuit-heavy system such as a suitable Vue kit offers a different kind of insight—but only if it is electrically approved for the installation.
A three-phase home
Power and energy must account for each phase, not merely multiply one phase by three. Load can be asymmetric: an EV charger or heat pump may use different phases from the cooker. Pick a true three-phase monitor with correctly mapped current sensors and voltage references, or a suitable three-phase Modbus meter. Check rated maximum current per phase against your incoming supply and CT aperture against actual conductor dimensions. A single CT around a whole multicore cable normally cannot measure each conductor’s power use separately.
Solar generation and export
Be precise about what the sensor measures. A grid-boundary meter can tell you net import and export; it cannot, by itself, tell you both house consumption and gross PV generation at every instant. If you need production and consumption separately, measure the inverter output independently or use an independently integrated inverter production sensor.
For example, if solar produces 3.0 kW and the house uses 2.0 kW, the grid sees approximately 1.0 kW export, ignoring losses and storage flows. Treating the PV output as grid export would overstate export by 2.0 kW. A battery adds further measurement boundaries: charging, discharging and grid exchange are distinct quantities.
Use the appropriate import and export cumulative energy entities rather than a signed instantaneous-power value in the wrong dashboard field. Sign conventions vary: check whether the particular meter reports positive export, negative grid power or separate import/export registers.
How the data reaches Home Assistant
| System | Normal data route | Where it can fail | Practical check |
|---|---|---|---|
| Shelly | Device → LAN/Wi-Fi → built-in Shelly integration → recorder/statistics | Local networking, discovery, firmware, power supply | Disable internet temporarily while retaining LAN; confirm power and energy continue updating |
| Emporia Vue | Vue → vendor cloud → supported app / community integration → Home Assistant | Internet, cloud account/service, integration compatibility | Confirm current custom integration support and whether historical totals survive reconnection |
| Modbus | Meter → RS-485 or TCP → bridge/host → Modbus integration → recorder/statistics | Serial settings, register map, cabling, gateway and scaling | Read known voltage/frequency values first, then validate accumulated kWh against meter display |
For the Home Assistant Energy dashboard, a power sensor measured in watts is not automatically interchangeable with an energy counter measured in kWh. The official Energy FAQ explains which device classes, units and state classes are required. An energy sensor normally needs device_class: energy, a compatible unit such as kWh, and state_class: total or total_increasing. If only power is available, an integration helper can estimate energy, but frequent interruptions and coarse sample intervals reduce confidence.
Configuration checklist before using the dashboard
- Verify the sensor’s instantaneous power against a known substantial load, using realistic tolerances.
- Confirm the cumulative grid-import counter rises during importing and does not fall unexpectedly after a reboot.
- Where solar is present, confirm the export counter rises during actual grid export, rather than using a total/net counter interchangeably.
- Check CT orientation and phase pairing through manufacturer-approved diagnostic procedures; incorrect signs or phase mapping can corrupt months of history.
- Make sure Home Assistant’s recorder has long-term statistics for the energy entities, then add the correct sources under Settings → Dashboards → Energy.
- Compare daily meter totals against the utility meter over several normal operating days; differences may arise from different boundaries and measurement tolerances.
If your sensor is missing from the dashboard, our Energy Dashboard troubleshooting guide covers common entity and statistics problems. For DIY readers comparing sensor approaches before buying a panel meter, see pulse vs CT vs PZEM vs Modbus monitoring.
Real installed cost: the advertised meter price is only the beginning
Retail prices change with region, tax, promotions and bundles, so a static price table will age quickly. Instead, calculate total installed cost from the exact locally available kit and its operating requirements. A €60-looking unit can be a poor deal if it needs additional CTs and extensive electrician time; likewise, a multi-channel kit may be economical per circuit even though its upfront price is higher. These are examples of cost drivers, not live quotations.
| Cost item | Shelly Pro / EM | Emporia Vue | Modbus meter |
|---|---|---|---|
| Meter and bundled sensors | Confirm Pro 3EM v2 three CTs; EM Gen3 listing one CT in base pack | Choose the precise branch-sensor count and mains kit | Choose direct-fed or CT-operated meter, certified variant |
| Extra CTs | For optional channels/capacity; model-compatibility essential | Extra branch sensors/second Vue if needed | Only if selected meter is CT-operated |
| Connectivity | Existing LAN/Wi-Fi; Ethernet run for Pro if desirable | Reliable supported network and internet service | USB–RS-485 adapter or certified gateway; cabling |
| Panel space and ancillary items | DIN space or approved enclosure; protection | Sensor clearance and approved power/wiring arrangement | DIN space, isolation where required and secure communications cabling |
| Commissioning and maintenance | Installer plus configuration and firmware checks | Installer plus app/account onboarding | Installer plus register mapping, testing and documentation |
| Cloud and subscriptions | Cloud optional for local HA integration | Cloud path essential; review current service terms | None required for local readings; optional hosted tools separate |
Ask the electrician to quote for survey + compatible hardware + protection/enclosure + fitting + commissioning + phase/import-export verification. Compare totals on the same scope, not a bare-device Shelly price against an installed Modbus solution. Do not assume all meters are approved for settlement or utility billing: for regulated measurement, check required MID and other national certification for the specific device and application.
Long-term reliability: think beyond today’s dashboard
Cloud dependency is an architectural risk, not proof that a product is unreliable. Emporia may be entirely satisfactory for household analysis, but its direct data access is dependent on the vendor cloud and its continuity. A community integration can change when authentication or cloud endpoints change.
Local integration reduces that dependence but is not maintenance-free. Shelly still requires power, functioning LAN/Wi-Fi and a supported software stack; firmware changes should be tested before deployment. Modbus’s open register-based approach can be durable, yet unstable RS-485 wiring, wrong termination or undocumented meter variants are common commissioning headaches.
History retention is another independent issue. On-device logs and vendor-cloud histories have their own limits. Home Assistant keeps eligible long-term statistics separately from short-lived raw recorder history, but backups and restores still matter. For automations such as dynamic EV charging, design a fail-safe if communication or measurements become unavailable; do not delegate electrical protection or charger safety interlocks to Home Assistant.
Buying decisions by household type
UK or EU single-phase house, mainly interested in bills and solar
Shortlist Shelly EM Gen3 with the precise supported CT size. It is especially attractive when Home Assistant is already running and the objective is locally accessible grid and possibly production monitoring. First confirm where the CTs would sit and whether both readings use the device’s supported single-phase arrangement. If you need many individual circuits, assess an officially compatible multi-circuit kit instead of assuming two inputs will reveal individual appliance usage.
Three-phase home, heat pump, EV charger or solar inverter
Start with Shelly Pro 3EM 120A v2 or a three-phase Modbus meter. Both fit the topology better than attempting to estimate other phases from a single clamp. Choose Shelly if you favour the straightforward native Home Assistant route and LAN connectivity; choose Modbus if you already have an RS-485 network, documented meter preferences or stricter requirements around local wired telemetry. Ask your installer to confirm CT capacity, feeder topology, panel space and whether additional independent measurements are needed for PV and EV.
North American-style panel with many circuits to investigate
Consider Emporia Vue 3 if the manufacturer confirms the particular model and kit is suitable for that supply and location, and you accept cloud-based reporting. Its multi-circuit capacity is a powerful diagnostic advantage over a three-channel whole-home meter. If your primary goal is an internet-independent automation system, its lack of a local device API remains a decisive objection.
Technical user wanting a completely wired system
Use a quality Modbus meter with a published, version-specific register map. Budget for an RS-485 adapter/gateway and commissioning time. There is no benefit in choosing the cheapest meter if register documentation is poor or if its import/export semantics are ambiguous. Our ESP32 Modbus SDM120/SDM630 guide covers implementation details; our ESP32 CT clamp article is a separate DIY measurement route rather than an installed-meter recommendation.
Common buying mistakes
- Buying a US kit for a European three-phase board: current-clamp fit alone does not establish voltage, frequency, approvals or wiring suitability.
- Confusing phase count with CT count: multiple sensors on one voltage phase do not necessarily measure multiple phases correctly.
- Assuming every API is local: a Home Assistant custom integration can still be a cloud client.
- Mixing power with energy: watts describe instantaneous rate; kilowatt-hours are integrated consumption or production.
- Counting the same load twice: do not add branch CT energy on top of a whole-home energy counter as if it were additional grid import.
- Ignoring import/export sign: a reversed clamp or mismatched voltage reference can make solar export appear as consumption.
- Shopping only by rated amps: CT aperture, compatible sensor type, low-load accuracy and actual breaker rating also matter.
- Omitting professional fitting: distribution-board work involves hazardous voltages even when the CT sensor itself is non-contact.
Frequently asked questions
Can I use Shelly with Home Assistant without Shelly Cloud?
Yes, for supported devices using the built-in local Shelly integration. You still need a working local network and Home Assistant host. Verify the specific meter model is supported and that your network permits local device communication.
Is Emporia Vue 3 a local Home Assistant energy monitor?
No. Emporia documents that Vue devices do not provide direct local API access. Community integrations may expose cloud-derived data to Home Assistant, but cloud access remains a dependency.
Is Modbus automatically more accurate than CT monitoring?
No. Modbus is a protocol. Accuracy comes from the meter’s sensor design, calibration, specifications and installation. Many Modbus meters themselves use CTs; direct-fed and CT-operated variants have different requirements.
Can one monitor show both electricity consumption and solar export?
Yes, when installed at the correct grid boundary with suitable bidirectional measurements, it can show grid import and export. Gross solar generation and total household load may require separate inverter or feeder measurements. Avoid double counting in the Home Assistant Energy dashboard.
Can I fit a CT monitor myself?
Do not work inside an energised distribution board. CT installation can involve exposed live conductors, and voltage-reference or meter supply connections are mains wiring. Use an appropriately qualified electrician and follow local electrical regulations and the exact manufacturer’s wiring diagram. Some CT types should not be disconnected from their measuring circuit while carrying primary current; follow the equipment safety instructions.
Verdict
For most serious Home Assistant installations where local ownership of the data matters, Shelly is the easiest starting recommendation: EM Gen3 for suitable single-phase monitoring and Pro 3EM for genuine three-phase supplies. Emporia Vue 3 is a strong choice for extensive branch-circuit visibility, provided your installation is supported and you accept cloud dependency. Modbus provides the clearest wired, locally polled route when you are prepared to configure, validate and maintain the meter-to-Home-Assistant connection.
Decide first what electrical boundary you need to monitor, then which readings your automations require, then whether cloud dependence is acceptable. Only after that should the number of sensors and purchase price determine the winner.
Official sources and further reading
- Home Assistant — Shelly integration (local push and supported setup)
- Shelly — Pro 3EM 120A v2 specifications and CT package
- Shelly — EM Gen3 specifications and supported CTs
- Emporia — Vue 3 product details and circuit capability
- Emporia — How Your Vue Works, cloud architecture and lack of local API
- Emporia — Vue offline behaviour
- Emporia — Monitoring more than 16 circuits
- Home Assistant — Modbus integration
- Eastron — SDM630 Modbus protocol reference (PDF)
- Home Assistant — Energy dashboard FAQ
- Home Assistant — Long-term statistics
Editorial note (October 2026): Product capability and integration distinctions are based on linked vendor documentation and Home Assistant references, not laboratory testing or a hands-on installation. Current local retail pricing, model availability and installation quotations should be checked before ordering.