Whole-home measurement delivers enormous value. You see total consumption, power over time, grid import, and, with solar, export too. It's the foundation for genuine energy analysis and for an Energy Dashboard with import and export. But installing a meter in your breaker panel isn't a trial-and-error exercise for a beginner.

Plan on about 65 to 75 minutes. This lesson is more conceptual than the last one. I won't show you how to wire up live conductors, because that's not something you learn from a guide. I'll show you what this kind of meter measures, what your options are, how to recognize flow direction in the data, and how to prepare a safe plan for an electrician to carry out.

One device versus the whole home

The outlet from Lesson 4 measured one load. A whole-home meter measures the entire installation at once, usually right at the point where it enters the home, after the utility's own meter. That's a different goal and a different risk. You plug a metering outlet into a regular socket. A whole-home meter gets installed in the breaker panel, often with current transformers clamped onto the phase conductors.

What a whole-home meter measures

A good whole-home meter gives you several kinds of data at once. These are what later feed the Energy Dashboard and your own dashboards. It's worth knowing what to look for before you pick hardware.

Where to install the meter alongside solar

With solar, where you measure matters a great deal. A meter installed at the home's grid connection shows the flow between the home and the grid: import or export. The inverter shows PV production. Those aren't the same data. Only together do they let you understand how much the home uses, how much it produces, and how much it sends back.

Single-phase and three-phase in plain terms

A single-phase installation has one phase conductor. A three-phase installation has three. Larger homes often have three phases, apartments more often have one. This matters, because the meter has to match your installation. A single-phase meter won't correctly measure a three-phase home.

With three phases, it also matters that the meter sums the phases correctly, and, if you have solar, that it handles the balance across phases according to your utility's billing rules. We'll refine that topic in the solar lesson. For now, remember: the number of phases decides which hardware to choose.

Shelly 3EM and Shelly Pro 3EM

A popular choice for whole-home measurement is the Shelly 3EM or Shelly Pro 3EM. It's a device installed in the breaker panel that measures three phases through current transformers clamped onto the conductors. It has a local integration in Home Assistant and usually exposes power, energy, import, and export, both per phase and as a total.

DIN rail meters with Modbus

An alternative is a DIN rail energy meter that communicates over Modbus. This is a popular option for people who want a meter that looks like a classic panel meter, integrated via Modbus RTU or TCP. In Home Assistant, you read the data through the Modbus integration, sometimes with ESPHome as a bridge.

Current transformers: what they are and what they're for

A current transformer is a component that measures the current flowing through a conductor without cutting into it. In the clamp-on version, it wraps around the phase conductor like a clip. That lets the meter measure a whole home's large currents safely for the electronics. It's what makes measuring an entire home possible at all, not just a single outlet.

The breaker panel isn't a place for trial and error

This is the most important part of this lesson. In earlier lessons you could experiment risk-free. Here it's different. A live breaker panel can kill. There's no room for trying, checking, and undoing here. One mistaken touch can end in electric shock, fire, or damage to the installation.

When to call an electrician

The short answer: always, for anything inside the breaker panel. Your part is planning and configuring the data. The electrician's part is the physical install, connecting the transformers, checking the phases, and safely powering everything back up. A good split of roles gets you great data with no risk.

How to check import and export direction

After installation, your role returns. In Developer Tools, States, check whether the data makes sense. When the home draws power from the grid with no solar involved, import should climb and export should sit still. If you see the opposite, a transformer is probably connected backward, or import and export are swapped.

Compare the data over several days

After installation, don't judge everything after five minutes. Over several days, compare the trend against your utility's meter, your inverter's app, or your bill across successive periods. Don't expect agreement down to the last hundredth of a kWh, but large differences, a reversed direction, or odd spikes are a signal to revisit the configuration or the installation.

Ready-made import and export template sensors

Sometimes a meter gives you a single power entity that's positive during import and negative during export. For the Energy Dashboard, it's more convenient to have two separate energy entities. Below is an example of splitting power into import and export, then building energy from them with Integration from Lesson 3. Swap the names for your own.

Splitting power into import and export

template:
  - sensor:
      - name: "House Power Import"
        unique_id: house_power_import
        unit_of_measurement: "W"
        device_class: power
        state_class: measurement
        availability: >
          {{ states('sensor.house_power') not in ['unknown', 'unavailable', 'none'] }}
        state: >
          {% set power = states('sensor.house_power') | float %}
          {{ [power, 0] | max | round(1) }}

      - name: "House Power Export"
        unique_id: house_power_export
        unit_of_measurement: "W"
        device_class: power
        state_class: measurement
        availability: >
          {{ states('sensor.house_power') not in ['unknown', 'unavailable', 'none'] }}
        state: >
          {% set power = states('sensor.house_power') | float %}
          {{ ([power, 0] | min | abs) | round(1) }}

Now you turn these two power values into energy with Integration, exactly as in Lesson 3. Import and export in kWh will then feed into the Energy Dashboard's Electric grid category.

Import and export energy

sensor:
  - platform: integration
    source: sensor.house_power_import
    name: "House Energy Import"
    unique_id: house_energy_import
    unit_prefix: k
    unit_time: h
    method: left
    round: 2
    max_sub_interval:
      minutes: 5

  - platform: integration
    source: sensor.house_power_export
    name: "House Energy Export"
    unique_id: house_energy_export
    unit_prefix: k
    unit_time: h
    method: left
    round: 2
    max_sub_interval:
      minutes: 5

What to add to the Energy Dashboard

Once you have import and export in kWh, add them to the Energy Dashboard under Electric grid, just as in Lesson 2. Import is energy drawn from the grid, export is energy sent back. If you have solar, you'll add production under Solar panels, but we'll cover that in detail in the solar lesson.

Common mistakes

Assignment: a safe plan for whole-home measurement

Key takeaways

What's next

In Lesson 6 we'll move into solar: PV, import, export, home consumption, self-consumption, battery storage, and dynamic pricing. The whole-home measurement from this lesson is the foundation solar analysis depends on. Only once you know how much the home draws and sends back does panel production start telling you something useful.

If you finish this lesson with a safe whole-home measurement plan, and you know what you'll do yourself versus what you'll leave to an electrician, you're exactly where you need to be. The scale grew, but the principle stayed the same: safety and data first, then decisions.