Documentation: Example for pure Home Assistant MQTT Zeroexport / Nulleinspeisung with Battery & AHOY-DTU Automation

[beebee]

Hello,

I tried to find a pure and simple Home Assistant only solution for a Zero Export / Nulleinspeisung automation without NodeRed and python scripts, additional RPIs, tools etc to simply work directly with HA & ahoy-du via MQTT and didn't find any matching my requirements. So I created my own with some support from ChatGPT to enhance it further and would like to share it here so others can use it as a starting point.

You need:

• A HA sensor state which holds your current total household/grid power usage where negative values mean export to grid and positive import from grid. I have an extra sensor for each (positive) - you can replace/calculate household power to your needs in the automation curGridUsage. (I have Shelly 3EM and also Tibber Pulse)
• Power switch(_switch.switchonoff_inverter_AC_battery_tohouse) with Sensor (_sensor.power_battery_tohouse) for your Homilies Inverter AC output that you are using for unloading your battery. Automation can work without and would use/can use previous battery power setting if actual power not available alternatively. Might need to disable condition if no switch available.(I have Shelly Plug flashed and power calibrated with Tasmota)
• a new input_number and input_boolean for control of the zero export in your configuration.yaml. Not using any initial value means last value is saved between HA restarts. Can adjust min/max/step on slider which is holding/showing the calculated automation value or can be manually set when _batterynulleinspeisung is off:

  
  input_number:
  battery_limit:
  name: Battery Nulleinspeisung Limit
  min: 0
  max: 120
  step: 1
  mode: slider
  # initial: 0

input_boolean: battery_nulleinspeisung: name: Battery Nulleinspeisung icon: mdi:battery-heart-variant

initial: false

- Automation. You need to adjust the MQTT Topics to match your ahoy-dtu inverter target. Can set min, max battery power, hysteresis. If _input_boolean.battery_nulleinspeisung_  is flipped off, you can use the slider for _input_number.battery_limit_ to manually set the battery limit and skip the calculation. Inverter target will be turned off/on dynamically with the first MQTT publish when lower than 7W which you can adjust there of course in the template. My HM-400 does not follow any limit values below 8W so switching off is better for my battery for "idle" power saving (Bluetti EB70 only). Also HM400 stays in "hot-standby" and is turned on and power-set  directly when MQTT limit is calculated for higher again or manually set 

alias: AHOY-DTU Battery Nulleinspeisung mit Hysterese description: >- Hält den Battery-Power-Limit für die Nulleinspeisung durch die Batterie aufrecht. trigger:

• platform: time_pattern seconds: /20 condition:
• condition: state entity_id: switch.switchonoff_inverter_AC_battery_to_house state: "on" enabled: true action:

• service: input_number.set_value target: entity_id: input_number.battery_limit data_template: value: >- {% set minBatteryPower = 0 %} {% set maxBatteryPower = 75 %} {% set hysteresis = 5 %}

  {% set oldBatteryLimit = states('input_number.battery_limit') | float %}
  {% set newBatteryLimit = oldBatteryLimit %}
  
  {% set curGridUsage = states('sensor.power_import') | int - states('sensor.power_export') | int %}
  {% set curBatteryPower = states('sensor.power_battery_to_house') | int(oldBatteryLimit)  %}
  
  {% set powerFlow = curGridUsage + curBatteryPower %}
  
  {% if is_number(powerFlow) and is_state('input_boolean.battery_nulleinspeisung','on') %}
    {% if powerFlow >= maxBatteryPower and oldBatteryLimit != maxBatteryPower %}
      {% set newBatteryLimit = maxBatteryPower %}
    {% elif powerFlow <= maxBatteryPower and powerFlow + hysteresis < oldBatteryLimit %}
      {% set newBatteryLimit = powerFlow + hysteresis %}
    {% elif powerFlow <= maxBatteryPower and powerFlow - hysteresis > oldBatteryLimit %}
      {% set newBatteryLimit = powerFlow - hysteresis %}
    {% endif %}
  {% endif %}
  
  {% if newBatteryLimit <= minBatteryPower %}
    {% set newBatteryLimit = minBatteryPower %}
  {% endif %}
  
  {{ newBatteryLimit }}

• service: mqtt.publish data: topic: inverter/ctrl/power/0 payload_template: |- {% if states('input_number.battery_limit') | int < 7 %} 0 {% else %} 1 {% endif %} retain: true
• service: mqtt.publish data: topic: inverter/ctrl/limit/0 payload_template: "{{ states('input_number.battery_limit') |round }}W" mode: single

Hints:

• ahoy-dtu does not seem to read the retained power on/off state when subscribing to the MQTT broker/topic after a reboot from my experience. I suggest you set some lower persistent limit on your battery inverter directly via ahoy GUI.
• You can switch off the input_boolean and set battery_limit to 0 (so this automation will send an inverter off) before powering off the Inverter AC smart plug after a delay is a great other automation idea if your RCD/FI doesn't like full-load cutting ;)
• I turn of/on this automation here with others based on my virtual battery SOC

[lumapu]

do you see any task for me so far?

is it a big problem?

ahoy-dtu does not seem to read the retained power on/off state when subscribing to the MQTT broker/topic after a reboot from my experience. I suggest you set some lower persistent limit on your battery inverter directly via ahoy GUI.

Should we think of publishing such tutorials / examples on https://ahoydtu.de?

[beebee]

No big problem from my side about the retain. I was putting it here for documentation/people to fiddle with and thought it might be helpful for the GitHub Wiki for the HA users. No Idea really about how big the need is - Examples on ahoy website sound nice to me.