Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.

How to adjust amperage of wall connector to match solar output?

I have just had a Powerwall and 22 solar panels (9.24kWp) installed so excuse me if my newbie question sounds naive. Being in the UK the solar output varies significantly during the day - maximum is 5kW (set by the electricity company) and my “base” demand level as I call it is around 0.9kW during the day. I also have a Tesla Model 3 with Tesla Wall Connector which can charge at a maximum of 7.4kW (32A). My ideal scenario is for my solar panels to cover my house needs and then fill my Powerwall. This I can easily achieve. But then I’d like to charge my Tesla car battery at whatever is the maximum amperage possible without importing from or exporting to the grid. I can do this manually by keep looking at the solar output and reducing or increasing the amperage on my Tesla Wall Connector, but that’s not realistic on a minute by minute basis. Is there an automatic way that my system can adjust the amperage by referencing the total energy requirement of house plus car. So to give an example, if my solar output is 5kW and my Powerwall is full, and my house demand is 0.9kW then I’d like to automatically set the Wall Connector at 16A as that equates to 3.68kW so falling within the 5kW output (0.9kW plus 3.68kW equals 4.58kW). But then if the solar output falls to 4kW I’d need the Wall Connector to drop the amperage to 12A (= 2.76kW) so that the total of house plus car falls to 3.66kW (2.76kW plus 0.9kW).

Oh and I don't want to use the Powerwall to fill my car battery!

Am I expecting too much from the above?
Last edited:
Am I expecting too much from the above?

From Tesla, currently? Maybe. Since you are in the UK, I would suggest searching the UK and Ireland subforum for this, as I believe there is a specific third party solution that people like out there. I think its called "Zappi" but I am not out there so cant speak to it personally.
  • Like
Reactions: glospete
Thanks for all the helpful comments.
Unfortunately Charge on Solar is not available in the UK else it may be a solution. I read about ChargeHQ and will investigate. AFAIK Zappi is a charger and not a software solution so as I have a Tesla Wall Connector I am loath to purchase more hardware.
So thanks again and I’ll investigate ChargeHQ.