Persistent values for sensor_total_energy and total_daily_energy

[ojwc]

Values for total kWh can be written to flash, so they can be restored after a reboot.

For total_daily_energy this is straightforward, just add to the config:
restore: True

For sensor_total_energy it is a little more complicated as there isn't any restore: flag defined. Define a global variable:

 globals:
  id: total_consumption
  type: float
  restore_value: True

Limit the frequency ESPHome will write to flash, to reduce wear on flash memory:

 preferences:
  flash_write_interval: 5min # or whatever value is preferred, it should be a long perio

Change the filters: section in total: part of pulse_meter to make the global variable equal to sensor_total_energy:

      filters:
        # multiply value = 1 / imp value
        # - multiply: 0.001
        - lambda: id(total_consumption) = id(sensor_total_energy).raw_state;
            return x * (1.0 / id(select_pulse_rate).state);

Finally to restore the total after boot, add on_boot flag to esphome:

  on_boot: 
    then:
      - pulse_meter.set_total_pulses: 
          id: sensor_energy_pulse_meter
          value: !lambda "return id(total_consumption);"

Now sensor_total_energy can be set to match the meter total and it will persist between reboots, as will total_daily_energy. Take care with ESP8266 as it has limitations for flash storage. Tested and working on ESP32 (nodemcu-32s).

[klaasnicolaas]

Feel free to make a pull request for this, then I will test it more specifically and possibly merge it if people want this.

./Klaas