Quick Summary (TL;DR)
Shelly Pro 3EM 120A v2 is the stronger choice when Home Assistant is the primary energy platform and you want a documented local integration. It reports power and energy for three measurement channels, supports single- and three-phase arrangements, includes three 120 A CTs in the referenced bundle, and has Ethernet plus Wi-Fi. Home Assistant’s built-in Shelly integration communicates directly with the unit over the local network; Shelly Cloud is not required. It also offers on-device history and documented automation/protocol interfaces.
Emporia Vue 3 is the stronger fit for detailed circuit-by-circuit visibility. The 8- and 16-sensor bundles can track many individual branches as well as the main supply, and the Emporia app is designed for approachable usage graphs, alerts and consumption analysis. Vue 3 supports suitable single-phase, split-phase and three-phase four-wire wye arrangements, with the correct main CT count and voltage references. But the stock Vue 3 is cloud-dependent: Emporia says it provides neither direct local device access nor a public API. A community Home Assistant integration uses Emporia’s cloud endpoints and may change or fail independently of the hardware.
Do not confuse Ethernet connectivity with offline integration. Vue 3 hardware lists a 10/100 Ethernet interface, yet Emporia still requires an internet connection for its standard monitoring service. Similarly, Shelly’s three inputs cannot individually profile 16 separate circuits. For a European three-phase home, compare supply topology, available panel space, CT fit, internet dependency, electrician labour and bundle contents—not the advertised price of the monitor alone.
Shelly Pro 3EM vs Emporia Vue 3 at a glance
This comparison is specifically between Shelly Pro 3EM 120A v2 and Emporia Vue 3 (standard manufacturer firmware). Vue 2 and a community-flashed Vue are different propositions, just as Pro 3EM-400 is not the same CT bundle as Pro 3EM 120A v2. Product detail and electrical suitability must be verified against the unit sold in your country.
| Feature | Shelly Pro 3EM 120A v2 | Emporia Vue 3, stock firmware |
|---|---|---|
| Main use | Three phase measurements, or three supported measurement positions | Whole-home mains plus detailed branch-circuit breakdown |
| Measurement inputs | Three supplied 120 A phase CTs; optional neutral monitoring arrangement depends on model and accessories | Up to three 200 A main CT inputs; up to 16 separate 50 A branch CT inputs |
| CTs in referenced pack | Three 120 A CTs | Two or three mains CTs by bundle; zero, eight or sixteen branch CTs by bundle |
| Suitable electrical systems | Shelly-documented single-phase and three-phase schemes; check wiring instructions | Single-phase two-wire; split-phase three-wire; earthed four-wire three-phase wye with neutral; not three-wire delta |
| Network | Ethernet (LAN), 2.4 GHz Wi-Fi, Bluetooth provisioning | 10/100 Ethernet and 2.4 GHz Wi-Fi listed in manufacturer specs |
| Works with Home Assistant locally? | Yes: built-in Shelly integration (local push/RPC) | No supported local API on standard firmware |
| Official public API or direct local access? | Documented Shelly device APIs, HTTP/WebSocket/MQTT; manufacturer documents Modbus support | Emporia explicitly says no public API and no local device-data API |
| Home Assistant path | Built-in integration; direct to meter | Unofficial/custom cloud integration, e.g. magico13/ha-emporia-vue |
| Internet service outage | Local Home Assistant monitoring can continue while LAN/device/HA stay available | Cloud-side monitoring/data access impaired; not a dependable offline automation source |
| History/data | Up to 60 days of 1-minute device-side history advertised on v2 product page | Cloud: 1-second records 3 h, 1-minute 7 d, 15-minute records 1 year; coarser aggregates longer |
| Automation emphasis | Direct local HA automations, custom scripts, external systems | Emporia app-based insights, cloud integrations and product ecosystem |
| Installation | DIN rail; phase references and CT routing by qualified electrician | Panel gateway, mains and optional many branch clamps; compatible enclosure and approved wiring |
References: Shelly Pro 3EM v2 official specifications, Emporia Vue 3 product and package information, Emporia developer access statement and Home Assistant Shelly documentation.
What are you actually trying to measure?
The practical difference is not primarily the brand: it is three measurement positions versus up to sixteen branch circuits plus mains. With a three-phase supply, a Pro 3EM at the incoming conductors shows how much power is drawn or exported on each phase. It can show that phase B regularly spikes when a heat pump starts, but it cannot tell you which of six different breakers on phase B caused the event without more measurements. Vue 3 can dedicate individual CTs to those breakers, provided the installation, CT allocation and supported topology allow it.
Neither device automatically discovers appliances merely by measuring a main feeder. Disaggregating a meter trace into individual devices by guesswork is not equivalent to fitting a CT on each relevant branch. A monitor that records a main connection and a solar feeder also needs consistent energy boundaries if you want a correct total consumption number rather than double-counting solar production.
Example: a small three-phase house with a heat pump and EV charger
Imagine a home with three incoming phases, rooftop PV, a three-phase EV charger, an air-to-water heat pump and a few significant kitchen circuits. Pro 3EM can measure all three grid phases in one meter. To isolate EV, solar and heating consumption, you would typically need the inverter/charger telemetry, further properly selected sub-meters, or another suitable hardware arrangement. Vue 3 can use three mains channels on the three-phase wye feed and selected 50 A branch channels on eligible outgoing circuits; it can make the Emporia app more useful for fault-finding and appliance comparisons, but brings vendor-cloud dependence. Some three-phase equipment occupies more than one conductor and can require a carefully designed multi-CT mapping: do not simply assume one 50 A clamp equals one three-phase load.
Example: a UK flat with a single-phase supply
If the main goal is just hourly import/export totals in Home Assistant, a dedicated multi-circuit Vue kit can add installation complexity without much benefit. A local single- or three-channel Shelly unit may be enough, though you should also consider whether a smaller two-channel Shelly EM Gen3 is actually better suited to that single-phase job. Conversely, if your goal is to learn whether the oven, immersion heater, office, tumble dryer or heat pump drives your bill, numerous individual CTs are genuinely useful.
Connectivity: local control, Wi-Fi and Ethernet are three different questions
A meter can have Ethernet hardware and still require a vendor server for its usual application. Shelly Pro 3EM: the device can be reached on the local LAN and Home Assistant’s built-in Shelly integration talks directly to it. Home Assistant classifies Shelly as Local Push; Gen2+ devices use RPC communications. Shelly supports local web access and documented interfaces, though specific functions and availability depend on firmware and security settings.
Emporia Vue 3: the current manufacturer product listing includes both Wi-Fi and 10/100 Ethernet in the connection specifications and the installation guide identifies an RJ45 port. That does not mean you can point Home Assistant at the Vue’s IP address to read its energy channels. Emporia’s March 2026 developer-access statement says direct local data access is unavailable across its Vue devices, and there is no public API. Under stock firmware the device’s energy data is delivered through the Emporia cloud. A wired link can help network transport; it does not remove the cloud service as a dependency.
| Requirement | Shelly Pro 3EM | Emporia Vue 3 |
|---|---|---|
| Home Assistant host has LAN but no internet | Native local communication can continue | Standard cloud-dependent monitoring cannot be assumed to work |
| Local dashboards used for daily energy history | Built-in integration and Home Assistant Recorder | Unofficial cloud data integration may provide entities; must verify statistics and uptime |
| Fast control, e.g. load-shedding based on power | Direct local updates suit non-safety-critical automation (subject to system design) | Cloud latency/data cadence and third-party integration make it a less robust source |
| Manufacturer removes or changes online endpoints | Local integration less directly affected; keep firmware and LAN compatible | Custom cloud integrations may require code changes or stop working |
| Ethernet switch inside the plant room | Supported with suitable enclosure networking | Ethernet hardware available, but cloud still required for standard service |
| No third-party energy data storage wanted | Can run Shelly locally without Shelly Cloud | Stock Vue uploads operational data to Emporia |
What happens to your data during an internet outage?
For Shelly, distinguish three layers: the sensor taking a reading, local communication to Home Assistant, and Home Assistant’s Recorder writing to storage. Internet loss alone does not necessarily stop the first two. A failed local router, power supplyAliExpress price or Home Assistant host can still interrupt the flow. The Pro 3EM v2 product description advertises up to 60 days of one-minute on-device records; that is useful resilience, but recovery into your chosen Home Assistant statistics should not be assumed to backfill automatically without testing.
For Vue 3, Emporia explicitly requires internet connectivity for standard monitoring and offers cloud rather than device-local history. Its April 2026 documentation describes 1-second samples retained for three hours, 1-minute values for seven days and 15-minute exported values for one year, with longer-term aggregates at coarser resolution. That is a description of the manufacturer platform, not a promise that every one-second measurement is available as an entity to a custom Home Assistant integration. No local storage is offered as a user-accessible way to operate offline.
Home Assistant integration: official versus community-supported
Shelly: install using the standard integration
- Commission the electrical installation first. Have an electrician fit the correct CTs and voltage references, verify orientation and sign, and confirm the meter is running within its rated electrical environment.
- Put the Shelly and Home Assistant on a reachable local network. A wired LAN link may be simplest; if using Wi-Fi, check the signal quality inside a metal consumer unit. Network segmentation is fine if the correct device-to-HA communication is permitted.
- Open Settings → Devices & services. Accept a discovered Shelly device or add the built-in Shelly integration and enter its IP address. Home Assistant documents the direct integration and the newer RPC protocol.
- Check live power, phase readings and cumulative energy entities. Name and enable the appropriate sensors for the actual grid connection and subcircuits.
- Test it properly. Compare meter signs against an import/export period on the supplier meter, and confirm that a temporary WAN outage leaves the local dashboard updating.
Unlike a generic ESPHome device, you do not need to flash the Pro 3EM with alternative firmware just to obtain a native Home Assistant integration. For readers considering DIY alternatives, see our ESP32 monitoring methods comparison and SDM120/SDM630 Modbus guide.
Emporia: understand the HACS route before buying
Emporia Vue 3 does not appear as a built-in local-device Home Assistant integration. The community-maintained magico13/ha-emporia-vue project uses Python code to retrieve data from Emporia’s cloud service. Its README calls out minute-averaged usage per channel and describes installation through HACS as a custom repository. The project is not affiliated with or endorsed by Emporia. Authentication, endpoint behaviour, data availability and compatibility with a particular Home Assistant release can change.
That difference is material: you might see a one-second chart in the Emporia app yet receive minute-level observations in Home Assistant through a community integration. It is incorrect to market the stock Vue 3 as a native, guaranteed local-push Home Assistant monitor. Before buying specifically for Home Assistant, check the community integration’s recent releases and issues, confirm your Vue 3 hardware is supported, and decide how much maintenance you are willing to accept.
- Confirm the monitor works correctly in the Emporia app and that the cloud account has accurate channel labels.
- Follow the community project’s current documentation to install the HACS custom integration; do not confuse the GitHub project with a built-in Home Assistant integration or a Home Assistant add-on.
- Authenticate through the supported mechanism for your Emporia account, enabling only the required permissions.
- Inspect the created power and energy entities. Compare a few selected circuits against Emporia’s own graphs and check the update cadence.
- Examine the entity attributes and long-term statistics before adding grid, solar or individual-device data to Home Assistant’s Energy dashboard. Test resilience to HA restart and loss of the Emporia cloud connection.
What about flashing Vue 3 for local ESPHome?
Community projects have demonstrated alternative firmware on various Emporia Vue generations, and some discussion includes Vue 3. Do not assume older Vue 2 tutorials, pinouts, component definitions or instructions apply to your particular Vue 3 board. Firmware conversion is unofficial, may void warranties or invalidate product certification, can disable the normal Emporia service, and risks leaving a mains-installed product in an unsafe or unusable state. This article compares supported stock products, not a modified hobbyist device. A reader who values certified hardware and predictable maintenance should not make a purchase dependent on successful third-party flashing.
Data resolution versus useful automation speed
The term real time is often used inconsistently. A metering chip may sample internally many thousands of times per second while the app displays one-second averages and the automation interface presents minute-level values. What matters for Home Assistant is the update rate of the particular integration entity at the point where your automation reads it, not the fastest number quoted in a product brochure.
| Question | Why it matters | How to check |
|---|---|---|
| Does the dashboard show live W or kW? | Useful for seeing short peaks and when equipment starts | Watch a known, stable load change and time the sensor update |
| Does a kWh entity accumulate correctly? | Essential for meaningful Energy dashboard totals and billing comparisons | Check units/state class and record several hours alongside a reference meter |
| Can local rules run without internet? | Relevant to avoiding unwanted import during solar diversion or dynamic tariffs | Test with WAN disabled, only for a non-safety-critical monitoring scenario |
| Do branch readings correlate with mains? | Wrong CT directions/multipliers can break energy balance | Compare whole-home total, selected circuits and unmonitored “balance” |
| Is history still present after HA restarts? | Different data stores have different retention and backfill behaviour | Inspect the Recorder, statistics and vendor history after a deliberate maintenance restart |
The Pro 3EM’s local integration offers a more predictable foundation for control-loop input, though automation response also depends on firmware, network, Home Assistant timing, safe output actuators and electrical design. The Emporia app’s higher display resolution can still be excellent for understanding patterns in energy use. Neither device should be used as the only protective mechanism for overcurrent, grid disconnection, emergency stop or other safety functions.
Accuracy: do not compare marketing percentages without conditions
Shelly lists up to 1% active-energy measurement accuracy and Class B active-energy information for Pro 3EM, referencing manufacturer testing. Emporia describes Vue accuracy at approximately ±2% compared with utility meter readings and has separate documentation for main and branch current transformerAliExpress price performance. These figures are drawn from different test descriptions; they do not prove that one will always be more accurate in every real installation. At low currents, unusual power factors or incorrectly configured voltage references, errors can be materially larger.
Accuracy also depends on the topology. On a three-phase system a clamp on the right conductor with a voltage reference from the wrong phase can produce plausible-looking but wrong active power. Measuring a multi-conductor cable rather than a single individual live conductor can cause opposing magnetic fields to cancel. An open or poorly seated CT can generate confusing results and, for some CT architectures, create additional hazards. Let a qualified electrician fit and verify the system, using the relevant manufacturer instructions.
Single-phase, split-phase and three-phase: regional compatibility
For UK and EU homes, confirm the actual service configuration, not just the nominal country voltage. Shelly Pro 3EM 120A v2 is marketed in Europe and documents single- or three-phase wiring arrangements. Emporia Vue 3 documentation specifically lists single-phase two-wire, split-phase three-wire and three-phase four-wire wye systems with earthed neutral; the manufacturer warns that three-phase three-wire delta without a neutral is unsupported. Emporia’s technical data lists maximum 264 V line-to-neutral sensing, and the available main-CT ports and wiring harness must match the physical feed.
A common confusion is assuming that a product sold for US split-phase 120/240 V can simply use a two-main-sensor kit on a European three-phase 230/400 V supply. It cannot provide three separately referenced phases with only two mains clamps. Buy the correct three-phase Vue 3 bundle, or get explicit manufacturer confirmation that the chosen configuration and kit are approved. Likewise, a panel with additional neutral, PV and battery conductors may need more careful placement than the “three mains” illustration suggests.
Another confusion is reading the word Ethernet and concluding all communication stays private. Device-to-switch transport is a separate property from where its application data is processed. With Vue 3 stock software, vendor-cloud data flow remains part of the architecture even when a wired Ethernet connection is used.
Solar power, EV charging and batteries
Monitoring solar production and export
When measuring a solar installation, first identify whether the CT is positioned at the grid connection or the PV inverter AC output. A grid CT measures import or export through that connection, not necessarily total solar generation. For example, a house using 2 kW while PV produces 5 kW may export roughly 3 kW. If you put only a CT on the grid incomer, you do not know both household usage and full solar production independently unless other telemetry is available.
Pro 3EM provides four-quadrant measurement and phase-specific bidirectional data useful for an appropriate net-metering boundary. Vue 3 advertises solar and net-metering features; Emporia support documentation stresses that CT direction, calibration and branch allocation must be correct. Systems with batteries and multiple inverters are particularly prone to double-counting. Home Assistant’s solar documentation recommends using valid production energy readings, including inverter integrations where available.
Using energy readings to influence EV charging
For controlled EV charging, distinguish observability from enforcement. A local Shelly feed may help a Home Assistant automation decide that there is sufficient excess solar for a supported smart charger to increase its allowed current. But safety and load limits must be maintained by the charger, its approved installation and any manufacturer-required load-balancing arrangement. Do not treat either CT monitor as a certified charger controller by default. If an EVSE has its own supported integration, it may provide more precise charger status and energy statistics than deducing them from a feeder CT.
Heat pumps and large household loads
An isolated branch CT on a heat-pump feeder can help distinguish compressor consumption from other loads. However, a three-phase heat pump, immersion heater bank or distribution subpanel may need multiple CTs depending on wiring. Vue’s sixteen branch ports are not sixteen complete three-phase meter sets, and Shelly’s three CTs are not a substitute for a high-density multi-circuit monitor. If appliance-level costs are a primary objective, the Vue approach can be easier to interpret, but only if the stock cloud architecture is acceptable.
Total cost of ownership: price the installation, not just the device
Retail price alone is misleading here. As of the October 2026 manufacturer listings checked for this guide, Shelly’s European product page and Emporia’s US store show prices in different currencies and include different CT configurations. VAT, international delivery, supplier location, warranties and labour prevent an honest one-line “cheaper” verdict from those list prices. The proper comparison is the quote for a working installation in your panel.
| Cost or constraint | Shelly Pro 3EM v2 | Emporia Vue 3 |
|---|---|---|
| Base device | Check exact European 120A v2 SKU and current VAT-inclusive quote | Choose monitor-only, 8-circuit or 16-circuit bundle; verify region |
| Mains CTs | Three 120 A CTs in referenced v2 package | Two or three 200 A main CTs depending on package and supply |
| Branch CTs | No 16-circuit expansion built into one meter | 0, 8 or 16 50 A branch CTs depending on bundle |
| Installation labour | Phasing, meter protection, DIN-rail fit, CT routing, commissioning | Many sensors can require more time identifying and correctly routing individual circuits |
| Enclosure and cabling | DIN rail space and suitable Ethernet/Wi-Fi access | Gateway position, CT lead management, appropriate enclosure and Wi-Fi/Ethernet access |
| Internet/data | Local HA integration can avoid cloud reliance | Standard service uses Emporia Cloud; check data and account requirements |
| Software maintenance | Home Assistant core integration plus normal firmware maintenance | Manufacturer app or custom cloud integration updates, account management and community upkeep |
| Additional meters | May need additional meters/inverter/EVSE integrations for appliance breakdown | May need second Vue for more than 16 branch positions or unusual electrical topology |
| Country/warranty | Confirm Shelly distribution and approved electrical configuration | Confirm Emporia supplied kit, safety marking, retailer, local professional acceptance |
A realistic cost comparison without invented retail numbers
Write down the actual quote as meter + compatible CTs + enclosure and protection + data/network accessories + electrician labour + commissioning + any recurring service cost. Suppose one supplier has quoted a single Pro 3EM installation and another has quoted a sixteen-branch Vue installation. They are not functionally equivalent: the second includes a circuit survey and substantially more clamp placement. The Vue is not automatically better value simply because it offers more inputs; the Shelly is not automatically cheaper because it appears simpler. Decide first which measurements you will genuinely use.
A practical cost trap is a buyer choosing the Vue monitor-only configuration to save money while expecting sixteen individual appliances in the graphs. That bundle has no branch CTs. Another is ordering a two-main-CT Vue kit for a true three-phase installation. On the Shelly side, a buyer can mistakenly order the Pro 3EM-400 variant or a used previous-generation unit and then attempt to use incompatible clamp ratios. Check the full bill of materials and the electrician’s understanding of the model before buying.
Five buying scenarios: which is actually the better choice?
| Situation | Better starting point | Reason |
|---|---|---|
| Three-phase house; native Home Assistant is the priority | Shelly Pro 3EM | Direct local integration, per-phase measurements, wired connectivity |
| Single-phase house; identify 10+ breaker-level loads | Emporia Vue 3 | Many branch CT inputs and app-based circuit analytics, if cloud dependence is acceptable |
| Workshop where internet outages are common | Shelly Pro 3EM | Local access and HA monitoring without a cloud data path |
| Rental property owner seeking straightforward remote app insights | Emporia Vue 3, conditionally | App-led analytics may be attractive if tenant permissions, installer access, country support and cloud reliance are acceptable |
| Three-phase house with 12–16 important branches | Neither alone is a full substitute for the other | Decide between high-density cloud circuit metering and local phase/grid monitoring, or specify a multi-meter local system |
| Home Assistant owner planning PV diversion automation | Shelly Pro 3EM | Local timely input is preferable, but the inverter/EVSE may still be the appropriate control endpoint |
Installation and commissioning checklist
- Identify your electrical network. Confirm 1-phase, split-phase or three-phase wye/delta; document nominal voltage, neutral system and service rating.
- Define electrical boundaries. List grid import/export, solar generation, battery power, heat pump, immersion, EV charger and which branches you actually need to measure.
- Select the precise SKU and clamps. Check CT rating, quantity, conductor aperture and acceptable connection topology in the current installation manual.
- Have a qualified electrician check cabinet space and wiring protection. Physical room for many Vue branch sensors can be more limiting than the small gateway itself; Pro 3EM needs appropriate DIN mounting.
- Plan the network and data path. Determine whether you can tolerate an internet outage or vendor account failure; do not assume Vue 3 Ethernet enables a local HA integration.
- Commission every phase and CT. Validate phase references, direction, mains and branch totals. Use known loads and compare with available utility data over a meaningful period.
- Check the Energy dashboard. Use the correct cumulative kWh statistics for grid import/export and separate solar production. Avoid summing a branch already included in whole-home mains consumption.
- Validate failures and maintenance. Test after normal Home Assistant restarts, router maintenance and an internet interruption. Review firmware update notes and protect credentials.
- Retain documentation. Record circuit/CT mapping, model/revision, firmware, serial identification, installer notes and export/backup procedure for future troubleshooting.
Home Assistant Energy dashboard: common mistakes
Home Assistant’s Energy dashboard distinguishes power (W or kW at a point in time) from energy (kWh accumulated over an interval). A suitable energy entity generally needs device_class: energy, an appropriate state_class such as total or total_increasing, correct units and long-term statistics. A rapidly updating 1-second power trace cannot be substituted directly for a cumulative energy counter just by renaming it “kWh”. Conversely, a one-minute integration update may be entirely acceptable for daily energy accounting if the cumulative totals are accurate and consistent.
- Grid import versus grid export: use the appropriate separate cumulative measurements, not an unexamined signed net-power entity where the dashboard expects a particular energy statistic.
- Whole home plus subcircuits: do not add the sum of branch consumption to the already inclusive mains total.
- Solar generation: a mains export CT does not represent all PV generation when the household consumes some production onsite.
- Missing entities: verify each sensor’s unit, device and state class, Recorder inclusion and the Statistics troubleshooting page before assuming the hardware is incompatible.
- Gaps: cloud disconnections, HA outages and vendor retention policies affect which samples the dashboard receives; verify whether the integration backfills historical statistics.
Useful references include Home Assistant’s grid connection guide, Energy management FAQ and our Energy dashboard troubleshooting article.
Questions buyers frequently ask
Does Emporia Vue 3 work without the cloud?
Not through its standard manufacturer-supported monitoring interface. Emporia’s March 2026 documentation says no Vue product provides direct local API access and that measurements flow through Emporia Cloud. The stock product needs a working internet connection for its intended real-time monitoring service. Installing a LAN cable does not change the application architecture.
Does Vue 3 really have an Ethernet port?
Yes. The manufacturer’s current Vue 3 product specifications list 10/100 Ethernet, and its installation guide shows an RJ45 LAN connector. Some other Emporia support copy discusses Wi-Fi as the normal path, so check the precise unit and local installation options. In either transport configuration, the documented stock data service remains cloud-based.
Does Home Assistant officially support Emporia Vue 3?
There is a community-maintained, unofficial custom integration available from GitHub, which retrieves energy data using Emporia cloud endpoints. Do not mistake it for Home Assistant’s built-in Shelly integration or for an Emporia-supported local API. Confirm its compatibility and maintainability yourself before relying on it.
Will Pro 3EM show all sixteen circuits in my house?
No. The Pro 3EM 120A v2 has three principal measurement positions. It may measure the three phases of a main supply or suitable different positions in a manufacturer-supported single-phase scheme. To monitor many separate outgoing circuits you need additional metering points or a genuinely multi-channel system.
Can I put a Vue 3 into a European three-phase panel?
Potentially, on a supported earthed four-wire wye supply within the listed electrical limits, with three correctly placed mains CTs and approved voltage references. It does not support a neutral-less three-phase delta supply. Confirm the exact SKU, safety marking, installation manual, current capacity and approval with Emporia and a qualified local installer.
Are Vue 3 real-time one-second readings available to Home Assistant?
Not necessarily. Emporia advertises near-real-time app visibility, but the well-known unofficial HA integration documents minute-average usage readings through cloud services. Device sampling, app display, historical export and Home Assistant entity update rates are not the same quantity. Test the current integration if fast automation is a requirement.
Which has lower lifetime cost?
For a small number of locally monitored electrical boundaries, Shelly generally involves fewer sensors and is more predictable for an existing Home Assistant installation. For monitoring many circuits, one Vue bundle can reduce the need to purchase several separate metering devices, although the extra CT installation and dependency on the manufacturer service are significant. Actual comparison depends on local quotations and the exact sensor layout, not a simplistic per-device list price.
Final recommendation
Choose Shelly Pro 3EM 120A v2 for a locally controlled Home Assistant energy system, especially with three-phase import/export, solar or a need for dependable LAN operation. The built-in integration, local data path and clear phase measurement scope make it the better foundation for self-hosted dashboards and ordinary energy-aware automations. Treat its three inputs as a deliberate scope limitation rather than expecting appliance-level breakdown for a whole consumer unit.
Choose Emporia Vue 3 when your primary goal is to understand many branch circuits in the Emporia app and you accept the cloud requirement. It offers substantially more individual CT channels per device, but the custom Home Assistant integration is an integration-maintenance risk, and stock firmware cannot provide direct local data simply because the unit includes Ethernet. If both comprehensive circuit detail and fully local data are non-negotiable, do not force either product into an unsuitable role: evaluate a purpose-built multi-channel local meter solution instead.
Official documentation and further reading
- Shelly — Pro 3EM 120A v2: product specifications, CT bundle, protocols and on-device history
- Home Assistant — Shelly integration: built-in local push, RPC and setup
- Emporia Energy — Vue 3: monitor-only/8/16 CT bundles and technical specifications
- Emporia Energy — Vue 3 three-phase: wye-with-neutral support and delta limitation
- Emporia Energy — official Vue 3 installation guides and technical documentation
- Emporia Help — Developer Access & Future Integrations: no local device API and no public API
- Emporia Help — Data Storage and Management: published cloud retention windows
- Emporia Help — Will a Vue Work for My Home?: electrical supply compatibility
- Emporia Help — Vue 3 CT Accuracy: measurement conditions and limits
- Community project — magico13/ha-emporia-vue: unofficial cloud integration for Home Assistant
- Home Assistant — Electricity grid Energy dashboard documentation
- Home Assistant — Solar monitoring documentation
Editorial method: Manufacturer and Home Assistant documentation checked in October 2026. This is a documented-specification and integration comparison, not a hands-on test or a live retail price survey. Product revision, manufacturer cloud policy, firmware, regional suitability and Home Assistant custom integrations can change. Only a qualified electrician should open and work within a live distribution board or consumer unit.