Powerwall 2: Installation

[Frankman60]

As Mongo mentioned, the original 200 amp panel would only have a 200 amp breaker (no other breakers). All of the circuit breakers would move to the new 400 amp panel. This is the configuration for 2 PWs with all circuits backed up. With a single PW installation, the original main panel would be derated and only contain the circuits above 30 amps. The backup subpanel would contain the backup circuits that are less than 30 amps each.

Maybe you talked to the same contractor that I just talked to. He wanted to install a 400A subpanel, and I when I questioned him about it, he said the the additional current from the two powerwalls necessitated either a larger panel than my current 200A panel, or the main panel could be derated by installing a smaller service disconnect breaker. I don't have a formal proposal from him, yet, but he said derating the main panel would only save a few hundred dollars.

 

[Frankman60]

Yes, they can be floor stacked which means that the would be at the same height. But I was talking about stacking on a wall with only one PW on the floor and the other on top.

When they talk about stacked Powerwalls, don't they mean they are at the same level, like books in a bookcase with only one Powerwall attached to the wall and the others stacked in front of it?

 

[MorrisonHiker]

Yes, they can be floor stacked which means that the would be at the same height. But I was talking about stacking on a wall with only one PW on the floor and the other on top.

Ah, ok. I hadn't heard of anyone doing an install like that yet but it could certainly save some wall space if they can do it that way.

 

[wwhitney]

I was trying to reduce equipment cost.

Yeah, Tesla seems to like to throw extra panels in that can easily be avoided. Maybe they are just using a cookie-cutter design approach that can accommodate any situation on the ground.

The existing sub-panel has no main breaker, just the breaker feeding it in the main panel.

OK, that makes feeding the sub-panel from a breaker in your generation panel an option worth considering. But if the sub-panel accepts a main breaker, feeding it directly from the Backup Gateway is also a good option. It would leave you with headroom in your generation panel for future use.

Cheers, Wayne

 

[wwhitney]

As Mongo mentioned, the original 200 amp panel would only have a 200 amp breaker (no other breakers). All of the circuit breakers would move to the new 400 amp panel.

I'm under the impression that (2) 200 amp panels are cheaper than (1) 400 amp panel, considering the costs of equipment and wiring. In which case the "standard" install I described would be cheaper to implement than a "daisy chain" using a 400 amp panel. But perhaps I am mistaken about the costs.

Cheers, Wayne

 

[mongo]

I'm under the impression that (2) 200 amp panels are cheaper than (1) 400 amp panel, considering the costs of equipment and wiring. In which case the "standard" install I described would be cheaper to implement than a "daisy chain" using a 400 amp panel. But perhaps I am mistaken about the costs.

Cheers, Wayne

200 Amp panels runs ~$100 , 400A ~$400, so dual is cheaper for panels.

The 400 removes the need for a tapped feeder from the meter to the GW (with main breaker) and unbackedup panel (or dual lug base).

 

[wwhitney]

The 400 removes the need for a tapped feeder from the meter to the GW (with main breaker) and unbackedup panel (or dual lug base).

The topology you have in mind with versus without a 400A panel is not clear to me. If there is an existing 200A meter main, it is desirable not to have to change that out, since it requires involving the utility, and because Tesla charges more for changing the service panel. I'm not seeing any options that a 400A panel on a 200A service would provide that a different topology of 200A panels couldn't also provide.

Cheers, Wayne

 

[mongo]

The topology you have in mind with versus without a 400A panel is not clear to me. If there is an existing 200A meter main, it is desirable not to have to change that out, since it requires involving the utility, and because Tesla charges more for changing the service panel. I'm not seeing any options that a 400A panel on a 200A service would provide that a different topology of 200A panels couldn't also provide.

Cheers, Wayne

Ah, I was starting fresh. Yeah, if there is a 200A main panel that is staying, there aren't a lot of options.

 

[miimura]

It looks like my 400A main panel is a 320A continuous meter socket with a built in 200A breaker and bus for breakers and a second tap where you can optionally install another 200A breaker. I could not find the actual rating of the existing bus populated with breakers.

 

[mongo]

It looks like my 400A main panel is a 320A continuous meter socket with a built in 200A breaker and bus for breakers and a second tap where you can optionally install another 200A breaker. I could not find the actual rating of the existing bus populated with breakers.

Oh! So they can likely add the GW with main off the new 200A breaker and then a 200A panel (150 Amp main or less than 200A of breakers per Wayne's NEC reference) with the PV, PW, and backed up loads. Or , like you mentioned, 2 200Ampish panels, one generation and one loads, but that seems overkill.
Pics?

 

[wwhitney]

Do you have a make and model for your 400A meter main?

Cheers, Wayne

 

[miimura]

These are pictures of my 400A main panel before the PowerWall install, which was completed today.

There are 4 240V breakers that are installed but not used. The two A/C compressor units were never installed, and the range and the clothes dryer are wired, but gas appliances were installed.

Pictures post-install in the morning. It was dark when they finished.

They did not use the second possible service disconnect at the top of the panel. They used the existing 125A breaker (that was feeding the sub-panel) to feed the gateway. The feed line for the existing sub-panel was extended from the main to the load side of the gateway. One new panel was installed. The solar was moved to that panel by extending the wiring from the main, through the gateway box to the Generation panel. Three minor household loads (Bath GFI, Bath Lights, Bed #3 outlets) were relocated in a similar way to the Generation panel so they would be backed up. It was a relatively easy installation with the exception of hauling the PWs up the hill to the install location. Two guys roughly 10am-7pm.

 

[mongo]

These are pictures of my 400A main panel before the PowerWall install, which was completed today.

View attachment 277061

View attachment 277062

There are 4 240V breakers that are installed but not used. The two A/C compressor units were never installed, and the range and the clothes dryer are wired, but gas appliances were installed.

Pictures post-install in the morning. It was dark when they finished.

They did not use the second possible service disconnect at the top of the panel. They used the existing 125A breaker (that was feeding the sub-panel) to feed the gateway. The feed line for the existing sub-panel was extended from the main to the load side of the gateway. One new panel was installed. The solar was moved to that panel by extending the wiring from the main, through the gateway box to the Generation panel. Three minor household loads (Bath GFI, Bath Lights, Bed #3 outlets) were relocated in a similar way to the Generation panel so they would be backed up. It was a relatively easy installation with the exception of hauling the PWs up the hill to the install location. Two guys roughly 10am-7pm.

Thanks for the photos. Looking forward to the after shots.

 

[SoundDaTrumpet]

These are pictures of my 400A main panel before the PowerWall install, which was completed today.

View attachment 277061

View attachment 277062

Wow, a big thank you for taking a photo of the label. I have a calculated load that barely fits under the single 175A breaker with the 225A panel planned for installation. If I was to prompt Tesla Energy to allow for greater home loads, it looks like a 400A panel would be a great option. A 400A panel will have more back-feed available on the bus bars. This will allow a 200A single breaker for 25A towards future loads.

Ideally, there is no cost upcharge for the 400A. I plan to install a 30A heat pump water heater if the city allows for going over load calc by 5A, else install the new for 2018 15A heat pump water heater variant (Rheem brand). At least with the 15A heat pump, I can bump EV charging from 50A to 60A if I decided to install HPWC. Sounds like a plan, but open for comment (e.g. lower EV charging instead to 40A and go with 30A heat pump water heater).

 

[mongo]

Wow, a big thank you for taking a photo of the label. I have a calculated load that barely fits under the single 175A breaker with the 225A panel planned for installation. If I was to prompt Tesla Energy to allow for greater home loads, it looks like a 400A panel would be a great option. A 400A panel will have more back-feed available on the bus bars. This will allow a 200A single breaker for 25A towards future loads.

Ideally, there is no cost upcharge for the 400A. I plan to install a 30A heat pump water heater if the city allows for going over load calc by 5A, else install the new for 2018 15A heat pump water heater variant (Rheem brand). At least with the 15A heat pump, I can bump EV charging from 50A to 60A if I decided to install HPWC. Sounds like a plan, but open for comment (e.g. lower EV charging instead to 40A and go with 30A heat pump water heater).

I'm not sure the breaker section of that panel is rated any more than any other 200A panel (based on main breaker). I think the meter section is 400/320 and can only hit that using both service breakers. I checked the manufacturer web site, but came up empty. Basically, this set up works because the main panel has almost no active load breakers anymore.

 

[SoundDaTrumpet]

I'm not sure the breaker section of that panel is rated any more than any other 200A panel (based on main breaker). I think the meter section is 400/320 and can only hit that using both service breakers. I checked the manufacturer web site, but came up empty. Basically, this set up works because the main panel has almost no active load breakers anymore.

My initial intent was to suggest an installation of a Main Lug Only Commercial 400A Panel like the Bryant BR1224L400R (after the panel above). As for the photos above, I see the "200A max" and this would mean the breaker section and bus bar is sized at 200A. Thanks for pointing that out to be absolutely clear on this.

 

[miimura]

Here are the "after" pictures of my install. I should note that this was not a Tesla install, it was done by Swell Energy's contractor, a Northern California based solar installer. They had "fun" hauling the PWs up the hill and getting them on the wall mounts.

Only one PowerWall is currently connected. They did not have all the breakers on hand that they needed. The AFCI breaker for the relocated bedroom circuit is also missing, so it is still connected in the main panel. The Enphase micro-inverters are still happily talking over powerline to the Envoy even though the power is going back to the main panel through the Tesla Gateway to that one AFCI breaker that needs to be relocated.

 

[Frankman60]

Thanks for posting the photos Miimura. The location of the PWs is perfect, out of the way and looks like no sun exposure there.

How does the gateway connect to the Internet? I read in the specs that it has a cellular, WiFi or Ethernet connection. Does it just default to a cellular connection or do you have to connect it to your home’s WiFi? I have an Ethernet cable on the other side of the wall of the planned location so I was thinking of using that for Internet unless cellular is better.

 

[wwhitney]

The location of that hose bib is a working space violation of the NEC [Edit 2: That's 110.26(A). I was wrong about the dedicated equipment space, that only applies to indoor panels.]

Cheers, Wayne

 

[wwhitney]

I have a calculated load that barely fits under the single 175A breaker with the 225A panel planned for installation.

If you'd like my input, go ahead and post a one-line diagram of the existing configuration and of Tesla's proposed configuration.

Cheers, Wayne