Installing power walls soon. I need advice on car charging circuit.

[Babaron]

When solar panels were installed, power walls were not yet available and I indicated that I did not want a critical load sub panel as i wanted whole home back up for the power walls when they arrive.

Now that they’re going to be installed soon, I was thinking of how I might proceed considering that I’m going to be installing a car charging circuit as well. It may draw up to 100 A if available from my service. For reasons that have been discussed previously on this form, I do not want the car charging circuit to be backed up by the power walls but I want the rest of the home backed up.

Instead of installing a critical load subpanel, I was wondering if there might be a device that, much like for the solar panels, if the grid goes out, the switch would turn off power to the car charging circuit. Doing a grid outage, if I needed to get some charge, I could plug-in to a regular 120 V outlet for a little juice.

Any help would be appreciated.

Thanks,

Ron

 

[arnolddeleon]

Tesla could make this happen, but it hasn't. The raw pieces are there if you wanted to build it yourself. It's on my list of projects but too many others much higher on list right now.

arnold

 

[miimura]

Generally, Tesla won't install any breaker greater than 30A times the number of Powerwalls in the system on the Backup side of the Gateway. This means that if you have a 100A HPWC and two Powerwalls, Tesla will design the system so that the HPWC is not backed up.

The fact that you don't currently have a critical loads panel doesn't mean that they can't install the system so that it effectively has one. I have heard of installations where they made the original main panel the critical loads panel and installed a new panel to be the non-backup main panel. They did this by diverting the main feed from the meter away from the bus in the original main panel. The main reason for doing this is that you only have to run a couple heavy wires instead of moving all the small circuits in the main panel.

 

[davewill]

Here's an idea. Install a relay inside the wall connector and run the pilot wire through it. Since the pilot is low voltage it won't take a huge relay. Energize the relay from the mains so that if the mains go down, the relay opens and the pilot is disconnected from the car. If you also install a switch to in parallel with the relay, you could then easily choose to override and charge the car if you need to.