---
author: Sean Blanchfield
date: 2022-05-10 15:00
layout: post
link: https://seanblanchfield.com/real-time-device-power-meters-in-home-assistant
slug: real-time-device-power-meters-in-home-assistant
title: Real Time Device Power Meter for Home Assistant
image: /images/2022/05/power_meter.png
tags:
- Code
- Home Automation
---

I created a nice real-time power meter with device-level info to display on my Home Assistant dashboard. This shows the current overall power usage in the house, along with a bar chart that shows how it breaks down by appliance type. Here's how I made it.

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I display this power meter on my main dashboard, which is displayed on a wall mounted tablet in the kitchen. It's amazing how feedback like this can nudge your behaviour towards being more power efficient!

![The power meter in action, while I turn devices and appliances on and off around the house](/images/2022/05/power_meter.gif){: .captioned .right-half }

## Requirements
- **Home Assistant** (of course!)
- **Power sensors**.  I previously [posted about how I used Powercalc](/2022/02/virtual-energy-meters-with-powercalc) to create power and energy sensors that estimated the power usage of all the smart devices (and some dumb devices) in my house. Since then I've bought and installed a bunch of [Shelly Plus 1PM](https://shelly.cloud/shelly-plus-1pm/)s and [Shelly 1PM](https://shelly.cloud/products/shelly-1pm-smart-home-automation-relay/)s and (and some power monitoring zigbee smart plugs) to monitor the power usage of all our big dumb appliances.  I also bought and installed a [Shelly EM](https://shop.shelly.cloud/shelly-em-50a-clamp-wifi-smart-home-automation-1#139) to monitor total electricity usage at main supply to the house from my consumer unit/breaker box (and I got an extra clamp to measure my electric oven / stove 32A circuit). My Home Assistant now has a near complete view of electricity usage in my house. You'll might need something similar for this to be of use to you.
- **[Bar Card](https://github.com/custom-cards/bar-card)** to drive the basic bar chart (install from HACS)
- **[Config Template Card](https://github.com/iantrich/config-template-card)** to use javascript templates as values in Home Assisant YAML configuration (install from HACS if you don't already use it).
- **[Custom Card Mod](https://github.com/thomasloven/lovelace-card-mod)** to define custom CSS styles for the bar chart (install from HACS if you don't already use it)

## Creating the power categories

Power sensors that are generated by [Powercalc](/2022/02/virtual-energy-meters-with-powercalc) can be grouped together in the Powercalc config, which will automatically create summary sensors for the groups. For other devices, I had to make my own summary sensors. For example, I didn't want to clutter the bar chart by showing each cooking applicance individually; instead I wanted one "cooking" sensor that contained the power usage of all those appliances.

I created some template sensors to hold the current total power usage of devices in various categories. I already had some template sensors enabled from my `configuration.yaml` as follows:
``` yaml
template:
  - sensor: !include_dir_merge_list  templates/sensors/
```

This allows me to define template sensors by placing them in a new file in the `/config/template/sensors/` directory, as follows (`/config/template/sensors/power.yaml`):
{% raw %}
``` yaml

- name: cooking_power
  unique_id: cooking_power
  unit_of_measurement: W
  device_class: power
  state_class: measurement
  state: >-
    {{ 
      states('sensor.fuse_box_energy_meter_oven_and_hob_power')|float(0)
      + states('sensor.kettle_socket_power')|float(0)
      + states('sensor.microwave_smart_plug_power')|float(0)
    }}
```
{% endraw %}

## Creating the "Other" category

I also added a template sensor to capture the delta between the total measured power usage of the house, and the sum of all device-level power sensors (whether estimated by Powercalc or measured at the socket). This is the "*other*" category in the bar chart. It represents:
- discrepancies between reality and my powercalc estimates
- time discrepancy between sensors reporting in
- dumb appliances (like a hair dryer) that are being used from non-monitored sockets.

{% raw %}
``` yaml

- name: unaccounted_power
  unique_id: unaccounted_power
  unit_of_measurement: W
  device_class: power
  state_class: measurement
  state: >-
    {{ 
      (
      states('sensor.fuse_box_energy_meter_main_power')|float(0) 
      - states('sensor.all_estimated_usage_power')|float(0)
      - states('sensor.fuse_box_energy_meter_oven_and_hob_power')|float(0)
      - states('sensor.kettle_socket_power')|float(0)
      - states('sensor.microwave_smart_plug_power')|float(0)
      - states('sensor.dishwasher_power')|float(0)
      - states('sensor.washing_machine_power')|float(0)
      - states('sensor.dryer_power')|float(0)
      - states('sensor.fridge_smart_plug_power')|float(0)
      - states('sensor.tv_smart_plug_power')|float(0)
      - states('sensor.workstation_sensor_power')|float(0)
      - states('sensor.boiler_sensor_power')|float(0)
      - states('sensor.pump_sensor_power')|float(0)
      - states('sensor.comms_shelf_power')|float(0)
      - states('sensor.dining_room_socket_power')|float(0)
      )| round(1)
    }}

```
{% endraw %}

## Creating the Power Meter Cards
I placed the power meter code in the `yaml` file corresponding to a dashboard that I manage manually. If I was managing dashboards from the UI (as you probably are), I would have placed the code below in "manual" cards.

The main graphic is a native gauge card, defined as follows:

![The main power gauge](/images/2022/05/power_gauge.png){: .right-half }

``` yaml
  - type: gauge
    min: 0
    entity: sensor.fuse_box_energy_meter_main_power
    name: Current Electricity Usage
    max: 5000
    needle: true
    severity:
        green: 0
        yellow: 500
        red: 2000
```

The animated bar chart uses **Config Template Card** to define an array of variables, where each item is the entity ID of a power sensor and display name. It uses **Bar Card** to display those sensors. The list of sensors in the Bar Card is templated (courtesy of **Config Template Card**) to filter the variables array so that only sensors with a current reading of greater than 5W are displayed. The maximum value of the Bar Card is also templated, so the card automatically re-scales according to the highest current power value. Custom styling is then performed (courtesy of **Custom Card Mod**). 

{: .callout }
> It's a shame that **Config Template Card**'s `entities` array cannot itself be templated. Config Template Card monitors this list to re-evaluate templates whenever the state of those entities change. It turns out that it needs to be a literal list, and you can't use a template expression.

``` yaml

type: 'custom:config-template-card'
variables:
  - entity: sensor.cooking_power
    name: Cooking
  - entity: sensor.laundry_power
    name: Laundry
  - entity: sensor.dishwasher_power
    name: Dishwasher
  - entity: sensor.all_lights_power
    name: Lights
  - entity: sensor.fridge_smart_plug_power
    name: Fridge
  - entity: sensor.fridge_fake
    name: FakeFridge
  - entity: sensor.tv_smart_plug_power
    name: TV
  - entity: sensor.workstation_sensor_power
    name: Workstation
  - entity: sensor.boiler_sensor_power
    name: Boiler
  - entity: sensor.pump_sensor_power
    name: Pump
  - entity: sensor.comms_shelf_power
    name: Comms
  - entity: sensor.dining_room_socket_power
    name: Dining Room Socket
  - entity: sensor.estimated_device_power
    name: Estimated Devices
  - entity: sensor.unaccounted_power
    name: Other
entities: 
  # Note: this list of entities may seem redundant, but is necessary to inform
  # config-template-card which entities to watch for updates.
  - sensor.cooking_power
  - sensor.laundry_power
  - sensor.dishwasher_power
  - sensor.all_lights_power
  - sensor.fridge_smart_plug_power
  - sensor.fridge_fake
  - sensor.tv_smart_plug_power
  - sensor.workstation_sensor_power
  - sensor.boiler_sensor_power
  - sensor.pump_sensor_power
  - sensor.comms_shelf_power
  - sensor.dining_room_socket_power
  - sensor.estimated_device_power
  - sensor.unaccounted_power
element:
  type: 'custom:bar-card'
  entities: |- 
      ${ vars.filter(v => {
        let ent = states[v.entity];
        if(ent === undefined || ent.state === undefined) {
          console.warn(`Power meter: Entity ${v.entity} not found`);
        }
        else if(ent.state === 'unknown') {
          console.warn(`Power meter: Entity ${v.entity} state is unknown`);
        }
        else if(isNaN(ent.state)) {
          console.warn(`Power meter: Entity ${v.entity} state is not a number`);
        }
        else return Number(ent.state) > 5;
      }).sort((v1,v2) => states[v2.entity].state - states[v1.entity].state)}
    direction: right
    entity_row: true
    min: 0
    max: ${ Math.max(...vars.map(v => states[v.entity]).filter(e => !!e).map(e => e.state).filter(n => !isNaN(n))) }
  height: 20px
  stack: vertical
  decimal: 0
  icon: 'mdi:flash'
  positions:
    icon: off
    indicator: outside
    name: inside
    value: inside
  severity:
  - color: '#a1a1a18a'
    from: 0
    to: 2
  - color: '#3ea8328a'
    from: 2
    to: 10
  - color: '#85a8328a'
    from: 10
    to: 50
  - color: '#a8a4328a'
    from: 50
    to: 200
  - color: '#a887328a'
    from: 200
    to: 500
  - color: '#a867328a'
    from: 500
    to: 1000
  - color: '#a846328a'
    from: 1000
    to: 3000
  - color: '#a832328a'
    from: 3000
    to: 10000
  style: |-
    #states > * {
      margin: 1px;
    }
    bar-card-name,
    bar-card-value {
      font-size: 0.9rem;
      color: #ffffffaa;
      font-weight: bold;
    }
    bar-card-value	{
      font-weight: bolder;
    }
    bar-card-indicator {
      margin-top: 4px;
      transform: scaleY(-1);
    }
```