Myenergi Zappi calculating daily charge requirements and daily driving costs

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1

I want to have Home Assistant display how much I typically charge my car each day in kWh, as this will help me set my Zappi schedules more accurately to take advantage of the best rates. I am using the myenergi integration from HACS.

Here is where I have got so far:

Energy used each day

  • Create a template sensor to capture the final measure of sensor.zappi_energy_used_today
  • Create statistics sensors to calculate the mean and median of that value over 28 days

Here is my YAML:

template:
  - trigger:
    - platform: time
      at: "23:59:55"
  sensor:
    - name: "Daily Car Charge (max)"
       unique_id: "daily_car_charge_max"
       state: >
         {{ states('sensor.zappi_energy_used_today') }}
       state_class: measurement
       unit of measurement: "kWh"
sensor:
  - platform: statistics
    name: "Daily Car Charge (mean over 28 days)"
    unique_id: daily_car_charge_mean
    entity_id: sensor.daily_car_charge_max
    state_characteristic: mean
    sampling_size: 28
    max_age:
      days: 28
  - platform: statistics
    name: "Daily Car Charge (median over 28 days)"
    unique_id: daily_car_charge_median
    entity_id: sensor.daily_car_charge_max
    state_characteristic: median
    sampling_size: 28
    max_age:
      days: 28

Daily cost with variable energy cost
I am also trying to calculate how much I am spending on charging my car each day which complicated since I am on the Octopus Agile tarrif which has a different cost per kWh every 30 minutes. This means that I need to see how much I am charging my car every 30 minutes and multiply that by the rate at that time. I’m not sure the best sensor to use for this - I have opted to go for sensor.myenergi_home_power_charging but I suspect this wouldn’t work if I was using other myenergi products. I created a template helper to do the calculation with the following State template:

{{
  (states('sensor.octopus_energy_agile_current_rate') | float )
  *
  ((states('sensor.myenergi_home_power_charging') | float)/1000)
}}

That gets the cost at different times through the day like this:

image
image836×660 31.7 KB

I am still trying to figure out how to total this up each day so I can capture the daily total and start getting some interesting statistics about how much it costs me to drive each day/week/month/year. Perhaps a Reiman Sum Integral?

I’d love to hear if anyone else is working on this, or already has it nailed.

Also posted as a discussion in the Myenergi Integration github repo.

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2

Did you come to a final solution on this? Same query here, except right now I have Octopus Intelligent Go so a set day & night price but timings of night price vary depending on required charge.

4

I found the Dynamic Energy Cost integration in HACS which does the calculations for you. It is rough round the edges but works really well. You need to set it up for each device you want to track the cost of, then it gives you last day, month and year costs.

Repeat posting as I meant to reply to Captain Ted the first time.

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