Automation, time of day, Set a Helper value from a entity value

I get a sensor value that reads data from a text file OK.
meteossstarttime

I have a helper value (already with automation, when changed sends this value to my solar inverter)
input_datetime.economy_7_start

I can view both fine in simple entity cards

at 10pm I want it to read set input_datetime.economy_7_start with the meteossstarttime value.

I think basically asking, assume via an automation, how do I set X = Y

Post an example of the value of sensor.meteossstarttime. We need to know if it contains the date and time or just the time and also how it’s formatted.

Is input_datetime.economy_7_start configured to simply store the time or both date and time?

As for the automation, it will simply have a Time Trigger set for 22:00:00 and will set the Input Datetime to the sensor’s value.

Hi,

Sorry I have started another post, did not notice this reply & was trying to be more specific

I think it is a date/time issue and my data is text perhaps
sensor.meteokensstarttime is pulled from the text file

input_datetime.economy_7_start
I currently manually change in a card, this triggers an automation and a script that simply sends this value to my solar inverter & does work, does not seem to be an issue text or time here.

value: {{ states('input_datetime.economy_7_start') }}
value: {{ states('input_datetime.economy_7_start') | timestamp_custom('%H:%M:%S', default='00:00:00') }}

value: {{ states('sensor.meteokensstarttime') }}
value: {{ states('sensor.meteokensstarttime') | timestamp_custom('%H:%M:%S', default='00:00:00') }}

value: 05:00:00
value: 00:00:00

value: 18:45:10
value: 00:00:00

alias: example
trigger:
  - platform: time
    at: '22:00:00'
condition: []
action:
  - service: input_datetime.set_datetime
    target:
      entity_id: input_datetime.economy_7_start
    data:
      time: "{{ states('sensor.meteokensstarttime') }}"

References:
Time Trigger
set_datetime