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I am based in the UK. I have an electric vehicle charger:

enter image description here

  • Built-in protective earth neutral (PEN) fault device
  • Dynamic load balancing
  • Power output / max current: 7.4kW / 32A
  • Nominal supply: 230 V AC, 50/60 HZ
  • Protection: RCD Type A with 6 mA DC

I would like to know if it is possible to power my house battery from it, and what would be needed to do so. I have a solar system with a SOFAR 5KTLM-G2 single phase inverter:

AC attributes:

  • Max power:5000W
  • Max current: 22.8A
  • Single Phase

DC attributes:

  • Number of MPPT: 2
  • V range of MPPT: 90 - 580V
  • Max power: 6650W
  • Max current: 11A
  • Max voltage: 600V
  • Start up voltage: 120V

I also have a Solax 5.8kWh battery:

  • Nominal voltage: 115.2V
  • Operating voltage: 100 - 131V
  • Battery type: Li-ion (LFP)
  • Total capacity: 5.8kWh
  • Faradic charge efficiency: 99%
  • Battery roundtrip efficiency: 95%
  • System to inverter: CAN2.0
  • Battery to battery/BMS: RS485

From this, my basic understanding is that I could get a Type 2 EV charging socket like the one below and run it into the inverter. There would be a 5m cable run between the two.

enter image description here

Obviously the EV charger is too powerful for the inverter, but presumably there is a way around this. It's not something I'm going to do all by myself, obviously.

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    \$\begingroup\$ I'm struggling to understand why you would want to do this. \$\endgroup\$
    – Andy aka
    Commented Jan 6, 2023 at 11:20
  • \$\begingroup\$ V2H (or V2G) has been going through development over the past few years. You need the right car and the right charger and the right system. In theory you can homebrew it, but it isn't easy and with these voltages and power, it can be very dangerous. \$\endgroup\$
    – Puffafish
    Commented Jan 6, 2023 at 11:23
  • \$\begingroup\$ @Andyaka I am on a tariff from the power company where I pay around 20% of the standard rate to use the EV charger between 1am and 4am. \$\endgroup\$ Commented Jan 6, 2023 at 11:57
  • \$\begingroup\$ @Puffafish not sure if I explained well, but this has nothing to do with my vehicle. I want to go from the charger to the house inverter. Basically I want to plug the charger into the inverter, but due to power mismatch I assume I need some kind of load in between. \$\endgroup\$ Commented Jan 6, 2023 at 12:56
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    \$\begingroup\$ Why use an EV Charger? It will output mains AC (which you have available anyway), which you cannot use to directly charge your (DC) home batteries with. Can your inverter charge its batteries from mains AC? \$\endgroup\$
    – StarCat
    Commented Jan 6, 2023 at 15:31

2 Answers 2

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As Harper said, av EV "charger" is just wires, a plug to insert into the car, and a relay to power the plug if it detects car at the end of the plug. That's all.

Your solar inverter is a grid-tied model, not a hybrid. It's not compatible with a battery, it can't produce power in a blackout, and it can't be used if not connected to the grid.

So you have three things (EVSE, battery, inverter) that are not designed to work together.

If you want to charge your car with "free" excess solar electricity during the day, then you need a power router, and an EVSE that supports it. There are various ways to do this, it depends on how the components can talk to each other. For example some EVSE's will query the inverter via modbus, others will just measure the total power used by the house. Basically, if the whole house (solar inverter included) is exporting power to the grid because there's a lot of sun, an EVSE that supports this can use this "wasted" excess power to charge the car.

If you want to do something with your battery, then you need an inverter that supports this battery. This can either be a hybrid inverter to replace your Sofar, or a separate AC-coupled storage inverter. It's a high voltage battery, so you should be very careful in selecting the inverter, because they tend to be compatible with a very short list of battery models and brands. Some of these combinations (notably hybrid) tend to work in blackouts, others don't and just allow timeshifting.

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You just called that thing an EV charger, which means the project is already off the rails.

That thing is an EVSE. It is nothing but a gateway. It simply connects normal 240V AC to the automobile. It also detects certain faults in the AC power supply, and tells the EV how much current is safe to draw from the connection. The connection from utility to car is nothing but wires. Really.

The charger is onboard the car.

So, you see you don't need the EVSE at all... your missing ingredient is a battery charger appropriate to your battery pack.

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