Have a look at my YT video on how to use a Panasonic heatpump and Homeassistant to start controlling the heatpump.
The required scripts can be found here: https://github.com/simonsays-techtalk/HAPA
Update: Homeassistant 2024.2 modbus (and maybe others as well) require the precision: 1 setting in your modbus config for the temp sensor. Might look like this:
name: Temperature sensor
address: 1
precision: 1
scale: 0.1
unique_id: tempsens1
unit_of_measurement: °C