Discussion: "Powerwall +"

[wwhitney]

First, it doesn't take an electrician to realize that a standard panel for a home contains more amps "in breakers" than the actual amps feeding the panel. That's because, I guess, no one figures all the breakers will be at max.

Not only that, but because each component is protected at its rating. The panel will have a main breaker (or upstream breaker for an MLO subpanel) whose rating does not exceed the bus rating. So the failure mode if you suddenly load all the branch circuits to their maximum (unlikely) is that the breaker for the panel trips.

Cheers, Wayne

 

[slcasner]

Initially I proposed that they would use a meter socket adapter to provide both a disconnect and perform the equivalent of a line-side-tap as is done with other "Renewable Meter Adapters". Existing Powerwall 2s to get 50% power capacity increase with SW update...

This is simpler - and there must be a reason why they explicitly state that this is not a line side tap. Harder to get approval?

Maybe there are some places that require a single grid disconnect? Or maybe a concern that when the PW is charged from the grid for storm watch the rating of the service line could theoretically be exceeded by the sum of the main panel breaker and the PW breaker?

The main downside of this not being a line-side tap is that on 100-125A panels which are pretty common, this will not let you backfeed more than 20% of the main panel's busbar rating, unless it also has some secret-sauce that monitors current on both the main feed and the solar/battery feed at the same time to avoid overloading the main panel.

My main breaker is 100A on a panel upgradeable to 125A, so I guess my configuration would be limited to 25A. But my existing PV system (panels + PbA batteries) installed in 2000 is through a 70A breaker! So I don't know what permitting trouble I might run into for replacing this system with Solar Roof and PW+.

 

[wwhitney]

My main breaker is 100A on a panel upgradeable to 125A, so I guess my configuration would be limited to 25A. But my existing PV system (panels + PbA batteries) installed in 2000 is through a 70A breaker! So I don't know what permitting trouble I might run into for replacing this system with Solar Roof and PW+.

If your panel bus is rated 125A, with a 100A main breaker, then you can put in an inverter breaker opposite the main for up to (1.2 * 125 - 100) = 50A of inverter breakers (*). Hard to see how it would make sense to use a 70A breaker and feeder for that. There's some chance the bus is rated for 150A, in which case you'd be allowed 80A of inverter breakers. If the panel's label is intact, the fine print should spell out the bus rating.

Cheers, Wayne

(*) The limit is actually on 125% of the inverter maximum current, not the breaker, and the breaker might be rounded up to the next size. Not likely to be an issue here since the computations come out to standard breaker sizes.

 

[miimura]

Interesting - so they are only using the meter socket adapter to act as the disconnect when the grid goes away.

Initially I proposed that they would use a meter socket adapter to provide both a disconnect and perform the equivalent of a line-side-tap as is done with other "Renewable Meter Adapters". Existing Powerwall 2s to get 50% power capacity increase with SW update...

This is simpler - and there must be a reason why they explicitly state that this is not a line side tap. Harder to get approval?

The main downside of this not being a line-side tap is that on 100-125A panels which are pretty common, this will not let you backfeed more than 20% of the main panel's busbar rating, unless it also has some secret-sauce that monitors current on both the main feed and the solar/battery feed at the same time to avoid overloading the main panel.

It's not just a disconnect. I'm pretty sure it's also:
- Site Grid power flow measurement
- Voltage sense feedback (used to detect grid status and synchronize the AC waveform before reconnecting to the grid)

 

[slcasner]

If your panel bus is rated 125A, with a 100A main breaker, then you can put in an inverter breaker opposite the main for up to (1.2 * 125 - 100) = 50A of inverter breakers (*).

Right, I was not calculating that correctly. Thanks.

Hard to see how it would make sense to use a 70A breaker and feeder for that. There's some chance the bus is rated for 150A, in which case you'd be allowed 80A of inverter breakers. If the panel's label is intact, the fine print should spell out the bus rating.

The label is kinda legible; photo attached. My interpretation is 125A for the bus rating. If I recall correctly, the 70A breaker was used because 60A or 50A compatible with this panel could not be found. The inverter is a Trace SW5548, max 5500W or 46A continuous.


Back to the Powerwall+ topic now...

 

[winfield100]

The way it was explained to me.

First, it doesn't take an electrician to realize that a standard panel for a home contains more amps "in breakers" than the actual amps feeding the panel. That's because, I guess, no one figures all the breakers will be at max.

Anyway, since I got 3 PWs I really wanted to know if the three (90 amps) would work, or whether I should get 4.

My electrician, who is a nice guy but definitely on the spectrum, said, "OK, lets test it."

He came out with some sort of guage and we turned on every electrical load in the house, AC, every light, every flat panel, every computer, left all the doors open on two refridgerators and two wine coolers, ---- you get the picture.

He said "you're going to draw about 70 amps."

I said, how do you know that? He said, "unless you have a pool pump, three koi ponds, an elevator, or a bowling alley, its always about 60-70 amps for a 2500-3000 square foot house."

He was right. I did not, by the way, have the 60 amp Tesla wall charger at full blast for the test because I view that as an optional load.

So I have one 200 amp panel. As I said, 800 amps sure sounds like a lot unless its oversized for some reason.

I would suggest you do the same test, because that is the real data you need to know to get enough powerwalls.

@Southpasfan
that is quite intriguing:
turn on everything to get max draw and check
realizing i have a Sense monitor with clamps around the mains and the solar PV inputs that monitors all stuff

just turn everything on, including pool heater, pool pump and A/C and get an actual number
i will know the number of PW’s i actually need and if i need a bigger panel

thank you

 

[Vines]

We have 800amp service going in our new construction house and I just requested our (hopefully) soon to be installed 35kw solar/4PW system be changed to PW+ so we can backup the entire house instead of just one 200amp panel. Does anyone know if PW+ will work with 800amp (or even 600amp) service for whole home backup? I don't really know how it backups up the entire house so I'm curious if anyone has any insight.

Thanks!

In addition to all the other issues, 800A meters are totally different meters and not compatible with the Powerwall+ meter disconnect.

Once you get past 400A services, the power no longer flows through the meter so this method of disconnecting the meterwill not work. 600A and larger services have CT meters which sense power flow but the power does not flow through them.

You can have whole home backup but you must use multiple gateways, and likely more than 4 Powerwalls. For instance we just backed up most of an 800A service in Atherton (except the pool) with 3 gateways and 12 Powerwalls.

 

[Southpasfan]

In addition to all the other issues, 800A meters are totally different meters and not compatible with the Powerwall+ meter disconnect.

Once you get past 400A services, the power no longer flows through the meter so this method of disconnecting the meterwill not work. 600A and larger services have CT meters which sense power flow but the power does not flow through them.

You can have whole home backup but you must use multiple gateways, and likely more than 4 Powerwalls. For instance we just backed up most of an 800A service in Atherton (except the pool) with 3 gateways and 12 Powerwalls.

12 PWs! I bet the solar array was fairly large as well

I have system size envy. Ha!

Of course, its all relative to the amount of electricity used. I have learned a lot about use in three months, thats for sure.

 

[Vines]

12 PWs! I bet the solar array was fairly large as well

I have system size envy. Ha!

Of course, its all relative to the amount of electricity used. I have learned a lot about use in three months, thats for sure.

Imagine an Atherton mansion, 40 kW of PV will cover most of their projected usage lol.

 

[oholladay]

Looks like new Powerwall specs have been posted on Tesla website. Also, the software update notes have been updated to say “selected regions and devices.” So, I’m wondering if this update has some element of increased power to it

 

[wwhitney]

Moreover, the spec sheet and owner's manual are available here:

Powerwall Owner Documents | Tesla Support

Download ownership documents on Powerwall specifications, warranty and supporting equipment.

www.tesla.com

Cheers, Wayne

 

[GenSao]

Moreover, the spec sheet and owner's manual are available here:

Powerwall Owner Documents | Tesla Support

Download ownership documents on Powerwall specifications, warranty and supporting equipment.

www.tesla.com

Cheers, Wayne

Awesome!

Tesla integrating and simplifying the install process. When permitted, the Powerwall+ and Backup switch (and solar panels) are all you need. The Backup Gateway 2 is now optional.

 

[Kilotango74]

So is the powerwall+ optional, the new standard,…….or what. I see no way to select when ordering. I have a recent order for a 12.25 system w/2 powerwalls. Will i be switched to the powerwall+?

 

[GenSao]

So is the powerwall+ optional, the new standard,…….or what. I see no way to select when ordering. I have a recent order for a 12.25 system w/2 powerwalls. Will i be switched to the powerwall+?

@Kilotango74 ,

Powerwall+ is likely the new standard. Tesla has options:

• If solar only, the new Tesla Solar Inverter (or a third party inverter) would be installed.
• If adding Powerwalls without new solar, Tesla may opt to install the regular Powerwall 2 with the Backup Gateway 2. There is no need for the solar inverter included with Powerwall+.
• If adding Powerwalls and solar, the Powerwall+ should be installed. Depending on supply, Tesla could go the classic route of Powerwall 2 + Power Gateway 2 + separate inverter.

Since your order is for solar and Powerwalls; Powerwall+ are likely in your order. A 12,24 kW system will likely get you 2 Powerwall+ as each Powerwall+ is limited to an inverter of 7.6 kW (24 solar panels). If you had 8.16 kW of solar, Tesla could pair a Powerwall+ with a Powerwall 2.

The use of the Backup Gateway 2and/or Backup Switch will vary on location (what is permissible by your local building official, site constraints, and supply).

Ultimately, check the product specification on your account and contact your advisor if you want to use Powerwall+.

 

[h2ofun]

Help me with more details. How does the powerwall + avoid permits? How is it better or different than the PW2? Is the difference is
mainly the inverter is built in? From all the hassles, I sure glad I have a SE inverter.

 

[scotsmanswan]

A few observations based on these newly released details:

1) Powerwall+ specs (Powerwall | Tesla) are for combined Inverter plus battery - see the * noting full sun is 7.6kW continuous and no sun is 5.8kW (the later just being the battery). Off grid is 7kW continuous with no sun - not sure why being off grid allows more power but perhaps changing the voltage output is used to increase power which could not be done while on grid?
2) Powerwall 2 specs seem to suggest the same 5.8kW peak as underlying Powerwall+ battery. Presumably the 5.8kW continuous is limited by the 30A fuse used in Powerwall 2 installations (i.e. 5.8kW = 80% * 30A * 240V)? Also is the underlying battery of Powerwall+ essentially a Powerwall 2? If so this might suggest Powerwall 2 is capable of 7kW continuous but the 30A fuse limits this (as Powerwall+ with no sun can do 7kW)?
3) Powerwall 2 Owners manual (https://tesla-cdn.thron.com/static/N8RQWT_Powerwall_2_AC_Owners_Manual_NA-EN_1LQFPK.pdf?xseo=&response-content-disposition=inline;filename="powerwall-2-ac-owners-manual-en-na.pdf") refers to to following part numbers as Powerwall 2 AC: 1092170-xx-y, 2012170-xx-y, or 3012170-xx-y. So will all Powerwall 2's eventually be capable of 5.8kW continuous on grid with FW update?
4) Powerwall 2 Technical Specs sheet (https://www.tesla.com/sites/default/files/pdfs/powerwall/Powerwall_2_AC_Datasheet_EN_NA.pdf) does not appear to have been updated yet (still shows 5kW peak). Yet to be seen but perhaps different Powerwall 2 part numbers may have different specs?

 

[MP3Mike]

2) Powerwall 2 specs seem to suggest the same 5.8kW peak as underlying Powerwall+ battery. Presumably the 5.8kW peak is limited by the 30A fuse used in Powerwall 2 installations (i.e. 5.8kW = 80% * 30A * 240V)? Also is the underlying battery of Powerwall+ essentially a Powerwall 2? If so this might suggest Powerwall 2 is capable of 7kW continuous in off grid situation but the 30A fuse limits this?

The specs shows Powerwall 2 has a 10kW peak: Powerwall | Tesla

The difference is a Powerwall+ has a 7kW continuous output, with no sun, while the Powerwall only has 5.8kW.

 

[scotsmanswan]

The specs shows Powerwall 2 has a 10kW peak: Powerwall | Tesla

View attachment 667884

The difference is a Powerwall+ has a 7kW continuous output, with no sun, while the Powerwall only has 5.8kW.

Thanks for the pointers - I made a couple of typos (which I have not corrected in the original).

I should have said: Presumably the 5.8kW peak continuous is limited by the 30A fuse used in Powerwall 2 installations (i.e. 5.8kW = 80% * 30A * 240V)? Also is the underlying battery of Powerwall+ essentially a Powerwall 2? If so this might suggest Powerwall 2 is capable of 7kW continuous in off grid situation but the 30A fuse limits this (as Powerwall+ with no sun can do 7kW)?

 

[h2ofun]

Thanks for the pointers - I made a couple of typos (which I have not corrected in the original).

I should have said: Presumably the 5.8kW peak continuous is limited by the 30A fuse used in Powerwall 2 installations (i.e. 5.8kW = 80% * 30A * 240V)? Also is the underlying battery of Powerwall+ essentially a Powerwall 2? If so this might suggest Powerwall 2 is capable of 7kW continuous in off grid situation but the 30A fuse limits this (as Powerwall+ with no sun can do 7kW)?

What is the wiring and fuses for the powerwall +?

Why the 80%?

 

[wwhitney]

A few observations based on these newly released details:

1) Powerwall+ specs (Powerwall | Tesla) are for combined Inverter plus battery - see the * noting full sun is 7.6kW continuous and no sun is 5.8kW (the later just being the battery). Off grid is 7kW continuous with no sun - not sure why being off grid allows more power but perhaps changing the voltage output is used to increase power which could not be done while on grid?

PW+ on grid power is throttled at 7.6 kW (edit: continuous) export to allow compliance with the 120% rule when interconnecting with a main panel with 200A busbar and 200A main breaker. When off grid, it's not necessary to throttle the power export, and the 50A breaker used for the power connection is sufficient for 9.6 kW continuous (with active PV)

2) Powerwall 2 specs seem to suggest the same 5.8kW peak as underlying Powerwall+ battery. Presumably the 5.8kW continuous is limited by the 30A fuse used in Powerwall 2 installations (i.e. 5.8kW = 80% * 30A * 240V)? Also is the underlying battery of Powerwall+ essentially a Powerwall 2? If so this might suggest Powerwall 2 is capable of 7kW continuous in on grid situation but the 30A fuse limits this?

A) Yes. Note that the original PW2 spec was 5 kW continuous but 5.8 kVA continuous--the latter allows for power factors other than unity. So PW2 has always been able to handle 24A continuous current, but the real power has been limited to 5 kW.

B) Probably

C) Maybe, but as you noted there are multiple part numbers for Powerwall 2, so it may be that only the newer model support this. Probably moot anyway as I doubt Tesla will want to deal with going back and reconfiguring those 30A breakers, along with reconsidering whether the existing upstream equipment and wiring complies with the NEC 705.12 requirements for the increased export.

Cheers, Wayne