Formatting template sensor works in development tool but not in value_template

Configuration
2 
  - platform: template
    sensors:
      irrigation_duration_for_1m2_all_day:
        friendly_name: "Sec/m² voor dag"
        unit_of_measurement: 's'
        value_template: "{{ '{0:,.2f}'.format((((states('sensor.verwachte_temp')|float + 30) ** 4)/75000) - (states('sensor.regen_verwacht')|float*16))}}"

Outer quotes should be different from inner quotes when the template is defined on the same line as the value_template option.

The alternative is a multiline format like this which doesn’t require outer quotes.

  - platform: template
    sensors:
      irrigation_duration_for_1m2_all_day:
        friendly_name: "Sec/m² voor dag"
        unit_of_measurement: 's'
        value_template: |
          {{ '{0:,.2f}'.format((((states('sensor.verwachte_temp')|float + 30) ** 4)/75000) - (states('sensor.regen_verwacht')|float*16)) }}

You should also supply float with a default value. For example, float(0) means it will use 0 if the entity’s value can’t be converted to a number.