yaml

How to: multiply two entities in Home Assistant

by
A screenshot of a YAML Template Sensor in Home Assistant that multiplies the values of two other sensors.

Suppose you have two entities in Home Assistant, and you want to multiply them together to produce a third entity that always shows the product of these two entities. Here’s how I went about it.

One of Home Assistant’s built-in integrations is Template. These Template entities derive their status from other entities in Home Assistant, and appear in the Home Assistant web interface as Helpers. You can do some fancy things with these, but all I want to do is multiply the value of one by the other.

Calculating export income

In my case, I wanted an entity that shows how much I’m earning from exporting excess energy generated by my solar panels, once our home battery is full. The amount exported is available as an entity in the SolaX Modbus integration that I use, expressed as a value in kWh. I also use the Octopus Energy integration with Home Assistant, and this has an entity showing my current export rate in £ per kWh. So, multiplying these together will show how much I should be making when I export.

This should be possible to set up as a Helper in the Home Assistant interface, but I personally found it easier to do so in YAML. Also, this is where I was able to ask ChatGPT to help write the YAML code. After tweaking its output to fit my needs, here’s what I’m using:

template:
  - sensor:
      - name: "Export income"
        unit_of_measurement: "£"
        state: >
          {{
           (
            states('sensor.solax_today_s_export_energy') | float(0) *
            states('sensor.octopus_energy_electricity_[mymeter]_export_current_rate') | float(0)
            ) | round(2)
          }}

The name is a human-readable name that I have given to the entity. The unit of measurement is optional – Home Assistant will accept just about anything you type in here, but as the amount will be currency I’ve put in the £ sign.

The ‘state’ bit is where I needed help from ChatPGT, as this isn’t really standard YAML here. We specify the first entity, and add '| float(0)'. The ‘float’ is necessary to provide a floating point number. The * character represents multiplication, and then we repeat the same notation for the second entity. Finally, we specify ‘| round(2)‘ so that the resulting entity rounds to two decimal places. Which, when dealing with an amount of money, makes sense as 0.3333 of one pence isn’t really worth knowing about.

As with any changes to Home Assistant’s YAML configuration, you’ll need to restart Home Assistant after setting this up. You’ll then have a nice new helper, in my case ‘sensor.export_income‘ to plop somewhere on your dashboard. Personally, I have it as a badge which appears once the value is higher than 0. Which, at this time of year, isn’t very often, but we did have a nice enough day a couple of weeks ago to be able to export some electricity.

How to disable go2rtc in Home Assistant

by

Home Assistant includes support for go2rtc, a streaming video application, which can be used to monitor and store footage from CCTV cameras. Since the November 2024 (2024.11) release of Home Assistant, go2rtc has been included in Home Assistant’s Default Config, which means that integration is loaded automatically on startup. If you don’t have any cameras to monitor in Home Assistant, this can mean some warnings appearing in your logs, and potentially slow Home Assistant down.

There are two ways to disable go2rtc if you don’t need it – a hard way and an easy way.

Hard way: Disable Home Assistant’s Default Config

You can tell Home Assistant not to load the Default Config. This gives you more control over which built-in integrations are loaded when you boot Home Assistant up, however, it means editing your configuration.yaml file. You’ll need to delete the ‘default_config:‘ line, and then create new entries for all the parts of the default configuration that you want to keep. This may be fine for simple installations, but for most users, this will add more complexity. I wouldn’t recommend this personally.

Easy way: Using HACS integrations

There are two HACS integrations that you need to install:

  1. Early Loader
  2. Default Config Exclude

These are not in the standard HACS repository, so you’ll need to open HACS, click on the three dots in the top right, select ‘Custom Repositories’ and then add the Github URLs in turn. You’ll need to install Early Loader first, restart Home Assistant, and then install Default Config Exclude next.

Once installed, you’ll still need to edit your configuration.yaml file, but instead you’ll only have to add a small block. Here’s mine:

default_config_exclude:
  - go2rtc
  - stream
  - cloud
  - my

What you’ll notice is that I’ve added some other integrations – stream, Home Assistant Cloud, and My Home Assistant. If you don’t have any cameras, then not only do you not need go2rtc, you probably don’t also need stream either. I don’t use Home Assistant Cloud or My Home Assistant, so I’ve disabled these too. As well as starting up a little quicker, Home Assistant also now uses slightly less RAM than before.