Home Circuit Review

[Kygo]

I'm about to get a P100D X and a model S after that so my house has been rewired with a 100a circuit for my two HPWCs. While doing that, I purposely upgraded all my breakers to tandems to leave space for a dual pole 40a breaker required for a future solar roof .



Tesla does not release wiring diagrams for the powerwall which is weird but I assume the powerwall is connected to the backfeed circuit breaker (which in this case would be the 40a dual pole that currently unwired) and the solar roof is going to plug into the powerwall, is that correct?

If the powerwall will need it's own backfeed circuit, I wont have space right now to plug in both a solar panel and the powerwall.

Since I am spending that much money for the roof+powerwall, I want the entire house to be backed up in case there is a blackout. Now from what I understand, I need to fit the gate way between the utility meter and my main panel, which is impossible given my panel integrates a meter socket. What I am going to do is to get a stand alone meter socket right next to my main panel and have my power company move the utility meter to that new socket. That way the gateway can be installed right between the meter socket and my main panel.

However, given that my panel currently only has 1 dual pole space left, any ideas on being able to fit both circuit breakers for the powerwall and solar roof lines in there?

My current idea is to use that last free dual pole breaker to wire in a subpanel right next to my main, and from there wire in the new solar and powerwall breakers.I know the solar backfeed needs to be the farthest breaker away from the main, so that will be last. Do powerwalls connect to each other or do they each need an individual circuit breaker? What size breaker will they require?




Any thoughts?

 

[roblab]

I would think that your two single circuit breaker spaces are all you need. If nothing else, you can move low-amp circuits to half-size breakers so your bigger circuits can use the doubles. Depends on what you have.

I don't have mine yet (three), but they talked like they would be wired in series, and fit into one circuit backfeed.

 

[cwied]

When they installed my Powerwalls, they moved all the circuits from the main panel to a load panel for whole-house backup. There's also a separate generation panel that has the solar and batteries connected. Finally, there's the gateway that sits in between the main panel and the other two panels. The only active breaker left in the main panel is the breaker that feeds into the gateway. I wouldn't worry too much about space in the main panel unless you're concerned about the aesthetics of having so many boxes on your wall.

My install was done by Tesla (i.e., what used to be SolarCity). I've seen several other pictures of similar installations in this group.

 

[Kygo]

I would think that your two single circuit breaker spaces are all you need. If nothing else, you can move low-amp circuits to half-size breakers so your bigger circuits can use the doubles. Depends on what you have.

I don't have mine yet (three), but they talked like they would be wired in series, and fit into one circuit backfeed.

everything else is already tandems now. The only thing that isnt tandem are the 2 pole 100a breaker for the hpwc and the 2 pole 40a breaker im reserving for solar.

 

[wwhitney]

A few comments:

- Each Powerwall interconnects with a 30A 2 pole breaker.
- PV interconnects with its own 2 pole breaker, whose size depends on the size of the system.
- Moving your service conductors and meter is going to be more expensive than installing a new panel downstream of your existing meter/main.
- The NEC has some not-so-simple rules about the maximum size backfeed allowed in a panel. These rules will apply to all panels between the meter and the Powerwalls/PV.
- You need to get a final compliant design before you put more effort into preparing for this installation. For example, most likely that meter main will be emptied of all breakers other than a feeder to the Gateway, so adjusting the breakers in it was likely a waste of time.

Cheers, Wayne

 

[SoundDaTrumpet]

I recommend doing as little as possible to accommodate a Powerwall installation because of a few factors: (a) contractor A (solar) and contractor B (battery) installed in different time frames are (i) focused on getting the job done as simply as possible (lowest cost / high margin) and (ii) contractor A conflicted with trying to accommodate for future battery system from a future contractor B; (b) the battery itself on how its integrated may change (e.g. PW version 1, PW version 2, AC connected, DC connected, future products); and (c) your mood/needs may change.

My personal experience:
1. Sketched a layout on where I planned PW1 would go. Result: I decided somewhere else later. PW v1 went from AC to DC coupled into PW v2. non-stack-able to stack-able. (Who knows if PW v3 will allow solar to connect to the battery thereby not needing a solar string inverter.)
2. Left room on service panel for more solar and battery thinking the meter panel will be utilized. Result: Tesla design empties the service panel of circuit breakers and will only have one breaker. Plan shows a new huge panel behind the meter-combo-load-center thereby rendering the meter-combo as a 'dumb' (wc?) pass-thru. Good thing I didn't jump to replace the meter-combo costing thousands (again here too forward thinking with solar and 100A EV charging). Tesla is replacing my meter-combo too, but their way, which is great. The meter-combo (15 years old) replacement didn't materialize until the 3rd iteration of the electrical plan.

I think the non-techie, casual approach works best, "Where do you want your Powerwalls to be placed" is likely the only thing one should be concerned with. Building a wall, structural fence, concrete slab, or dig a conduit so one can freely place/mount the Powerwall should be prioritized. You'll be looking at it for decades. Other than a bunch of wall-hung equipment, the electrical is supposed to be invisible (hands-off) to the customer. I find that Tesla does not overcharge for the electrical work such that doing anything ahead of time poses more risks than reward.