Feature request: Prevent car from taking power from battery

[gert28]

SolarCharger is working well for me apart from one issue.

Around 2 or 3 PM the home battery is fully loaded. Around that time the Tesla is often also charging at full speed and once the solar is no longer enough the (Zendure SolarFlow) homebattery starts adding it's power to help charging the car which is something I don't want because I want to use the power in the home battery to cover the night and early morning. Not enve talking about the efficiency loss there is from the 3 conversations (solar AC (mivroconvertors) -> home battery DC + battery DC back to home AC and back into the car battery DC).

It's OK that it keeps on charging but adapt it's power according to the excess solar. Now it stays on full (max) current because it is not aware that the homebattery is adding energy.

Is it possible to have a setting to specify the home battery and/or a toggle to prevent that the Tesla starts taking power from the homebattery? Or is ther another built-in way to achive this goal?

In simple terms: I want the car to use excess solar power only and prevent it from draining the home battery.

Thanks.

[flashg1]

I suggest to investigate if it is possible to use your net power sensor to control whether or not to charge from battery.

For your net power sensor, is it possible to include or exclude the power contribution from the battery?

If net power sensor can exclude the power contribution from the battery, then you should be able to charge from solar only.

Let me think about this to see if there is a better way.

[bpennypacker]

FWIW I'm currently testing the below template as my net power sensor. I have a Tesla Powerwall & gateway, and this template ensures the Powerwall is charged first and then the EV:

{% if float(states('sensor.my_home_battery_power')) < 0.0 %}
{{ (states('sensor.my_home_load_power')|float - states('sensor.my_home_battery_power')|float - states('sensor.my_home_solar_power')|float)|int }}
{% else %}
{{ (states('sensor.my_home_load_power')|float - states('sensor.my_home_solar_power')|float)|int }}
{% endif %}

The key here is that sensor.my_home_battery_power is negative when the Powerwall is charging and positive when it's providing power to the house. So when the Powerwall is charging then that is subtracted from the power available for the EV. When the Powerwall is not charging or is feeding power back to the house then it's not included in the calculation, so the power available to the EV is based solely on available solar & home consumption. When there's no solar available in that case then the EV shouldn't charge, so it won't drain the Powerwall.

[flashg1]

Hey @bpennypacker

From the equations above, is it true to say that 'sensor.my_home_load_power' has no battery component at all times, ie. whether battery is charging or discharging ?

[bpennypacker]

Yes, that's correct. sensor.my_home_load_power shows what the home is currently using. sensor.my_home_solar_power shows what the solar panels are generating, and sensor.my_home_battery_power shows what the Powerwall batteries are doing. All these sensors are provided by the Tesla Powerwall integration.