Divide by zero despite availabilty template

Configuration
1

Hello,

I am trying to get rid of a divide by Zero error, but it’s still there.
Basically I want to calculate the ratio of consumed solar energy. At night production is 0, so that’s a given.

My code is:

        value_template: "{{ (((states('sensor.daily_solar_production')|float(0) -states('sensor.daily_electricity_export_total')|float(0)) / states('sensor.daily_solar_production')|float(1))*100) | round(2) }}"
        availability_template:  "{{ 0 not in [states('sensor.daily_solar_production')|int]}}"

In the modelling tool, it returns “False” as availability so that should work.
Yet I still get error messages in the log

TemplateError('ZeroDivisionError: float division by zero') while processing template 'Template("{{ (((states('sensor.daily_solar_production')|float(0) -states('sensor.daily_electricity_export_total')|float(0)) / states('sensor.daily_solar_production')|float(1))*100) | round(2) }}")' for attribute '_attr_native_value' in entity 'sensor.daily_auto_conso_solar'

What can I do to solve that?
Using a If…Then could work but isn’t that clean is it?

2

Yes testing for 0 is the way to do it.

        value_template: "{{ none if states('sensor.daily_solar_production')|float(0) == 0 else (((states('sensor.daily_solar_production')|float(0) - states('sensor.daily_electricity_export_total')|float(0)) / states('sensor.daily_solar_production')|float(1))*100) | round(2) }}"
        availability_template:  "{{ states('sensor.daily_solar_production')|float(0) != 0}}"
3

Now, Frédéric has a point that the template shouldn’t even be rendered if its availability is False, functionaly-wise…

Whatever is using the template sensor should check that before rendering the sensor.

Frédéric, what is “using” the sensor? Is it only for display or is something else using it?

4

Try this without the changes to the value template:

availability_template: "{{ not is_state('sensor.daily_solar_production', '0') }}"
5

Hi, thanks for your feedback,

@koying,
Today this sensor is indeed only used for display, but I don’t exclude that I might use it for some automation (notification or whatever else) in the future.

@tom_l
I don’t think my availability_sensor is the issue, I have tried various versions and still have the same issue: even though the sensor shouldn’t be available, HA calculates it and thereby divides by 0.

6

And does it properly display as “unavailable”?

7

The availability template does not block rendering of other templates, it just means the entity’s state will be set to unavailable if the availability template returns False .

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8

So, to avoid “divide by zero” errors I have to do that?

        value_template: >-
            {% if is_state('sensor.hourly_solar_production', '0.0') %}
              {{ ('0' | float) }}
            {% else %}
              {{ (((states('sensor.hourly_solar_production')|float(0) -states('sensor.hourly_electricity_export_total')|float(0)) / states('sensor.hourly_solar_production')|float(1))*100) | round(2) }}
            {% endif %}
9

If you wish, you can reduce it by using a variable and an inline if statement:

        value_template: >-
          {% set hsp = states('sensor.hourly_solar_production')|float(0) %}
          {{ 0 if hsp == 0 else (((hsp - states('sensor.hourly_electricity_export_total')|float(0)) / hsp) * 100)|round(2) }}
1 Like
10

FYI

I thought you might be interested in this very recent PR:

If I understand it correctly, it intends to implement new behavior where if the availability_template evaluates to false, it will block rendering of other templates in the entity (i.e. its state/value_template).

2 Likes