Powerwall2 near the main panel or 200 feet away subpanel?

[h2ofun]

Thank you for the conduit size and wire size recommendations.
I will share this information with my electrician.

EVkid

I would oversize the conduit, assuming that is okay for code

 

[wwhitney]

Thank you for the conduit size and wire size recommendations.

Call it more of a "first draft" than a recommendation. : - )

Cheers, Wayne

 

[miimura]

@EVkid if I were in your situation, I would just tell the electrician that I needed 100A Generation panel for the solar and a 125A load panel for various loads in the garage. Make sure he understands that they have to be wired separately back to the main panel. Let him figure out the actual wire and conduit sizes since he has to get it to pass inspection and he has to pull the wire in the conduit when the time comes. Make sure to ask for the separate conduit for the Ethernet too.

 

[BGbreeder]

The only downside to letting the electrician run with it, is that the electrician will choose the smallest gauge wire that works. @wwhitney's points about energy losses are well taken, and worthwhile in my opinion as both halves of the electrical system here will see rather large power flows (for a residential use). All of the resistance heat is lost to the environment.

All the best,

BG

 

[miimura]

The only downside to letting the electrician run with it, is that the electrician will choose the smallest gauge wire that works. @wwhitney's points about energy losses are well taken, and worthwhile in my opinion as both halves of the electrical system here will see rather large power flows (for a residential use). All of the resistance heat is lost to the environment.

All the best,

BG

On the solar side, asking for the 100A panel is already effectively doing that since he's unlikely to have more than 60A of solar inverters. You could make the case that he should ask for a 200A feed and sub panel for the loads, even if it is only fed by a 125A breaker.

 

[wwhitney]

@EVkid if I were in your situation, I would just tell the electrician that I needed 100A Generation panel for the solar and a 125A load panel for various loads in the garage.

That's fine if you also impose a voltage drop requirement, given the 200 ft distance. I.e. a 100A feeder for the Generation panel that will only drop, say, 2% voltage at 60A. And likewise a 125A feeder for the Load panel that will only drop say, 2% at 80A.

Cheers, Wayne

 

[EVkid]

On the solar side, asking for the 100A panel is already effectively doing that since he's unlikely to have more than 60A of solar inverters. You could make the case that he should ask for a 200A feed and sub panel for the loads, even if it is only fed by a 125A breaker.

Now, I think I got a clear understanding of oversizing separate underground conduits, and oversized wires to minimize the power loss for both the load and the PV feed from a separate panel. (Question: Should I have the cut-off switch in the PV feed panel?).

Also, I understand now, that the reason why the PowerWall needs to be close to the main panel is that the Tesla Gateway unit that communicates with the Inverter in the PowerWall2+ needs to be in between the electrical meter and the main panel.

Question:
With the oversized load wires to the sub-panel and a separate data line(Ethernet), can the PowerWall2+ be installed in the detached garage and the TeslaGateway by the main panel? What are the pros and cons of this configuration?

Thank you,
EVkid

 

[BGbreeder]

The Powerwalls probably need to be within 66' (wiring) of the gateway, max. That is the communication limit of CANbus, which is what it looks like Tesla is using in the wired Gateway-Powerwall communications system. (I don't know that for sure, but that is what the chips and boards look like.) As it is the de facto standard for automotive communications, you can understand that there might be substantial in house expertise, and that the components are dirt cheap.

In general, it makes sense to have the powerwalls close to the gateway, and the gateway close to your main service panel to minimize power losses. Another way to think about it is that the goal is to try to minimize the length of big wires. Since you can't park them in the detached garage, it makes sense to have everything else close.

All the best,

BG

 

[miimura]

If you're in a new construction situation, you could turn everything around and put the meter and service entrance on the detached garage, then make the house a sub panel from there. That would allow you to have all the solar, powerwalls, and gateway all on the detached garage. You could even use two Powerwall+ and the backup switch that goes behind the meter. However, there may be other good reasons NOT to do this. If you already have the service installed on the main house, then just forget what I just said.