Homey Energy Dongle - Charge my Tesla with excess solar energy

Questions & Help
1

Hi everyone,

Like many of you, I recently purchased a Homey Energy Dongle. It provides valuable insights into my power usage and the energy generated by my 30 solar panels. In short, I want to create a flow to charge my Tesla Model Y with excess solar energy.

My goal is to minimize the amount of energy fed back to the grid. The flow should calculate how much energy is being returned to the grid and, based on that, adjust the amperage level in the Tesla app. I think checking every 5 minutes should be sufficient, as I’m concerned that more frequent adjustments might not be good for the onboard charger in my car. I have the following hardware:

  • Homey Pro 2023
  • Tesla Model Y
  • Ecotap charging stations (2x) unfortunately not controllable with Homey
  • 30 solar panels with a Growatt inverter

Any advice or examples on how to set up this flow would be greatly appreciated!

Best regards,
Pim

2

I have done exactly that. I think the flow does require some fine tuning, but this is a lot better than what I had: coming home in the dark, charging with 11KW using power of the grid only, next day the car is sitting idle and the solar panels are pushing everything to the grid.

Basically what I do:

  • The flow is triggered by an excess (I get that value from my Enphase inverter app)
  • If the difference between the previous value and the current one is over 500 Watt it proceeds
  • It calculates the Ampères by dividing the Watts excess by 692.8 and floors that value
  • Starts charging with the calculated current (I do that with the Tesla app)

The threshold of 500 Watts I put in to prevent too many commands being sent to Tesla through the Tesla API. I had 880 calls in one day when I started testing the first iteration.

3

I have done exactly that (just a different charger, but you should be able to use this)

You can read about it and download the flow in this thread:

It works perfect keeping the current close to zero (resolution of setting the curent is 1A, so you will always have a bit of overshoot)

4

Thanks for sharing! Looks pretty complicated, but I guess mine will be too if it is completely polished.

5

Thank you for your responses. I think that with the arrival of the Energy Dongle, the flows should be able to be simplified. Can someone help me with creating flows? The screenshots shared above look particularly complex.

6

Its not very complicated. Just several option repeating the same trick…
1st it calcultes the desired setting. Pretty straightforward: the energy dongle measures the power at the meter, substract the power that is delivered by the charger thats it)
Based on that setting there are 5 options

1 setting <6A,a charger requires a minimum of 6A. So this means no charging (or do charge when prices are low)
2 setting between 6A and 16A, single phase charging with the desired setting
3 setting is 17A, thats not possible so you need to choose 16A or 18A (based on low or high price)
4 setting is between 18A and 48A, 3phase charging with the desired setting
5 setting is >48A, 3phase charging on 48A

The flow also includes dynamic phase switching (between 1phase and 3phase). For my charger that requires a stop and start charging…
Might be different for your charger

7

thanks for your reply! Unfortunately the Ecotap chargers with Last Mile Solutions LMS (software) does not work within Homey. But luckily I can set charge speeds and limits with the Tesla Homey app. So there I can adjust the currents etc.

Could you maybe help me out with setting up the right flow?