Interestingly people often ask this question.

It would be obviously great if you could really do this because you stored your solar production at day time (while you are away at work) in your home battery and at night you like to charge your EV.

The short answer is: Yes.

The long answer Is: Yes, but it doesn't make too much sense. Here is why:

Let assume you have a Telsa Powerwall 2 as a home battery and a Tesla Model 3 as an EV.

  • The Powerwall 2 has a usable storage of 10 kWh.
  • The Model 3 has a usable storage between 50 kWh and 75 kWh (depends on the actual model).
  • You need about 12-15 kWh to drive a distance of 100 km.

So you can only charge your Model 3 less than 100 km with a fully charged Powerwall and then you need to import electricity from the gird to keep your house running until the sun shines again.

Keep in mind that other home batteries usually have a smaller capacity of 2 to 6 kWh so you can charge your EV only 12 to 50 km.

The obvious solution is to install many Powerwalls so you can fully charge your EV at night time. Sure you can do this but it will cost more than buying a new EV with the same battery capacity.

In the majority of all cases it will be simply much better to use your home battery to power your house only.

Vehicle to Grid

On the other hand it would be a great solution to power your house at night time with your large EV battery via "Vehicle to Grid". The latest model of the Nissan Leaf can technically do this but the bidirectional wall box might cost around AUD 10,000 which is insane.

However the upcoming Hyundai Ionic 5 will have "Vehicle to Load". This could power your house, but at this point in time it's not clear which kind of controller (wallbox) you would need to do this safely. Mynergi, do you read this?