Powerwall 2: Installation

[wwhitney]

Can someone help me understand the hardware required to install 2 PWs in a home with a single electrical panel with 200 amp service for whole home backup?

When you say a single electrical panel, is it a combination meter and electrical panel, where the meter is one side, all the circuit breakers are on the other side, and everything is in a single overall cabinet?

If so, that arrangement makes it impossible to do whole house backup without adding a second panel (or putting in a separate meter enclosure and abandoning the meter in the existing panel). The Backup Gateway has to be electrically between the meter and the backed up circuits, and there's no way to do that if the backuped circuits stay in a combination meter/electrical panel. You'd have to intercept the factory conductors from the meter side of the combo panel to the breaker side of the combo panel, and modifying those is not allowed.

Cheers, Wayne

 

[Frankman60]

Yes, what you described is exactly what I have an it is 200 amps. So the process would be to move all of the breakers from my original panel to a surface mounted sub panel? Then all that would be left in the original panel is the main 200 amp breaker at the top? That sounds like what the contractor said and I was trying to figure out why since the Tesla installation diagram doesn’t show a subpanel for whole house backup. Does that mean that it can only be done that way with a different meter/main service panel configuration? BTW, if a new subpanel is added for whole house backup and contains all of the breakers, should/will it upgrade the service from 200 amps to something higher? The contractor mentioned a 400 amp sub panel but it isn’t specified as a 400 amp panel on the estimate.

When you say a single electrical panel, is it a combination meter and electrical panel, where the meter is one side, all the circuit breakers are on the other side, and everything is in a single overall cabinet?

If so, that arrangement makes it impossible to do whole house backup without adding a second panel (or putting in a separate meter enclosure and abandoning the meter in the existing panel). The Backup Gateway has to be electrically between the meter and the backed up circuits, and there's no way to do that if the backuped circuits stay in a combination meter/electrical panel. You'd have to intercept the factory conductors from the meter side of the combo panel to the breaker side of the combo panel, and modifying those is not allowed.

Cheers, Wayne

 

[Frankman60]

When the subpanel is installed and it is surface mounted several feet from the main original panel, how are all of the wires attached to the breakers migrated to the new panel? The wires aren’t long enough to do that right?

It is most straightforward to install a new backup loads subpanel, and render your existing main service panel (MSP) empty with only one breaker to the new subpanel. The existing MSP is just for the meter and to hold a single 175 or 200 Amp breaker to the gateway and everything downstream. I did got not charged (N/C) for a main panel upgrade. My explanation for the N/C is they are adding panels and not removing/replacing the main service panel (the one that's flush mounted into your house). Adding surface mount panels are cheap and easy ($100 load center plus conduit and relocating breakers, which they were planning to do anyway) compared to replacing a main service panel (significant chore: disconnect PG&E feed, stucco work). Even so at $2500 for a true upgrade say 100A to 200A would be a reasonable. If it was to a 400A service all inclusive, that'd be a steal.

 

[wwhitney]

So the process would be to move all of the breakers from my original panel to a surface mounted sub panel? Then all that would be left in the original panel is the main 200 amp breaker at the top?

Basically. If you get n Powerwalls, then Tesla only wants to back up breakers no larger than 30*n amps. So if you have any breakers larger than that in your original panel, they would stay there.

Also, in addition to the main breaker, there will be a large (hopefully 200A) breaker to feed the Backup Gateway/new panel, unless your panel accepts subfeed lugs to do the same thing without a second breaker. [If some load breakers are staying in your existing panel, then your main breaker might need to be downsized, depending on several details.]

Is your original panel semi-flush with stucco?

That sounds like what the contractor said and I was trying to figure out why since the Tesla installation diagram doesn’t show a subpanel for whole house backup. Does that mean that it can only be done that way with a different meter/main service panel configuration?

Right, if the meter and main panel are in separate enclosures, as is common in much of the country other than California. I haven't checked the diagram you are referring to, does it show the meter in its own rectangle?

BTW, if a new subpanel is added for whole house backup and contains all of the breakers, should/will it upgrade the service from 200 amps to something higher? The contractor mentioned a 400 amp sub panel but it isn’t specified as a 400 amp panel on the estimate.

No need to upgrade the service. In fact, there's no need to use a 400 amp panel, the Backup Gateway has double lugs on the load side. So you'd three new enclosures: one for the Backup Gateway, one for a load center to feed the Powerwalls (and any solar), and one for all your backed up circuits.

Cheers, Wayne

 

[Frankman60]

Just to clarify, the quote is for 2 PWs and the original panel is semi-flush with the stucco. I was told that all loads/circuits would be backed up with 2 PWs regardless of the circuit size (amps). That would include these 50 amp breakers: NEMA 14-50 outlet, range/stove, AC.

Basically. If you get n Powerwalls, then Tesla only wants to back up breakers no larger than 30*n amps. So if you have any breakers larger than that in your original panel, they would stay there.

Also, in addition to the main breaker, there will be a large (hopefully 200A) breaker to feed the Backup Gateway/new panel, unless your panel accepts subfeed lugs to do the same thing without a second breaker. [If some load breakers are staying in your existing panel, then your main breaker might need to be downsized, depending on several details.]

Is your original panel semi-flush with stucco?


Right, if the meter and main panel are in separate enclosures, as is common in much of the country other than California. I haven't checked the diagram you are referring to, does it show the meter in its own rectangle?


No need to upgrade the service. In fact, there's no need to use a 400 amp panel, the Backup Gateway has double lugs on the load side. So you'd three new enclosures: one for the Backup Gateway, one for a load center to feed the Powerwalls (and any solar), and one for all your backed up circuits.

Cheers, Wayne

 

[jeep1979]

When you say a single electrical panel, is it a combination meter and electrical panel, where the meter is one side, all the circuit breakers are on the other side, and everything is in a single overall cabinet?

If so, that arrangement makes it impossible to do whole house backup without adding a second panel (or putting in a separate meter enclosure and abandoning the meter in the existing panel). The Backup Gateway has to be electrically between the meter and the backed up circuits, and there's no way to do that if the backuped circuits stay in a combination meter/electrical panel. You'd have to intercept the factory conductors from the meter side of the combo panel to the breaker side of the combo panel, and modifying those is not allowed.

Cheers, Wayne

 

[wwhitney]

Just to clarify, the quote is for 2 PWs and the original panel is semi-flush with the stucco. I was told that all loads/circuits would be backed up with 2 PWs regardless of the circuit size (amps). That would include these 50 amp breakers: NEMA 14-50 outlet, range/stove, AC.

OK, that works, sounds like all your branch circuit breakers are 50 amps or smaller, so Tesla is OK with backing them up with 2 Powerwalls. Your existing panel would end up with the 200A main and then either a 200A feeder breaker, or subfeed lugs. Worst case for moving the circuits over to the adjoining new 200A load panel would be that each circuit gets spliced in the current main panel to a short extension to the new load panel. There could be many conduits traveling from the existing semi-flush panel to the new surface mount panel, doesn't sound ideal.

Now, if you are willing to pay for some stucco work, Tesla may offer a semi-flush option for the new panels (probably not for the Backup Gateway but possibly for the other two). Or if you are using a contractor other than Tesla, they definitely could use semi-flush panels other than the Backup Gateway. Or depending on what's on the inside of the wall with the semi-flush panel, all the new panels could go there.

Cheers, Wayne

 

[jeep1979]

Yes, in my case a single panel as you described. However, Tesla, after the meter, ran the directly to the switch and then back to the main panel 200A breaker. This way they did not need a second panel. Not sure how to describe exactly what they did. Tomorrow, I can get a picture and annotate it. That said, Tesla brought power from the meter side into the breaker side, but bypassed all the breakers and ran the power then to their switch 200A breaker. They then ran the power back to my main panel to the 200A breaker that trickles down to the house breakers. This was the same as having basically an empty main panel running to the switch that then ran to a second 200A panel with all the breakers in it. This setup is working perfectly for me. Everything is powered correctly. Also, SCE had a planned power outage yesterday in my area that lasted over 8 1/2 hours. I was electrically isolated from the grid and ran off the batteries (and solar) without experiencing any problems. Keith

 

[Frankman60]

Thanks Wayne. I think I understand this now. The contractor wanted to install the backup loads subpanel in the garage behind the main existing panel because he said that was easier to do. But it probably also would look better because the migrated wires would not be seen. But putting the panel ther would also be difficult because there is conduit running along that wall and the NEMA 14-50 and other electrical components. Thanks again.

OK, that works, sounds like all your branch circuit breakers are 50 amps or smaller, so Tesla is OK with backing them up with 2 Powerwalls. Your existing panel would end up with the 200A main and then either a 200A feeder breaker, or subfeed lugs. Worst case for moving the circuits over to the adjoining new 200A load panel would be that each circuit gets spliced in the current main panel to a short extension to the new load panel. There could be many conduits traveling from the existing semi-flush panel to the new surface mount panel, doesn't sound ideal.

Now, if you are willing to pay for some stucco work, Tesla may offer a semi-flush option for the new panels (probably not for the Backup Gateway but possibly for the other two). Or if you are using a contractor other than Tesla, they definitely could use semi-flush panels other than the Backup Gateway. Or depending on what's on the inside of the wall with the semi-flush panel, all the new panels could go there.

Cheers, Wayne

 

[wwhitney]

Yes, in my case a single panel as you described. However, Tesla, after the meter, ran the directly to the switch and then back to the main panel 200A breaker.

Generally in a combination meter-panel the electrical connection between the meter and the panel consists of some bussing or fixed wires that are not to be field modified. Perhaps your panel is more flexible than typical, or perhaps Tesla pushed the envelope a bit. Presumably your city inspector signed off it.

Cheers, Wayne

 

[Frankman60]

The planned power outage was about the best test of your new PW system that you can get! It’s awesome that everything worked as designed.

Yes, in my case a single panel as you described. However, Tesla, after the meter, ran the directly to the switch and then back to the main panel 200A breaker. This way they did not need a second panel. Not sure how to describe exactly what they did. Tomorrow, I can get a picture and annotate it. That said, Tesla brought power from the meter side into the breaker side, but bypassed all the breakers and ran the power then to their switch 200A breaker. They then ran the power back to my main panel to the 200A breaker that trickles down to the house breakers. This was the same as having basically an empty main panel running to the switch that then ran to a second 200A panel with all the breakers in it. This setup is working perfectly for me. Everything is powered correctly. Also, SCE had a planned power outage yesterday in my area that lasted over 8 1/2 hours. I was electrically isolated from the grid and ran off the batteries (and solar) without experiencing any problems. Keith

 

[arnolddeleon]

Yes, in my case a single panel as you described. However, Tesla, after the meter, ran the directly to the switch and then back to the main panel 200A breaker. This way they did not need a second panel. Not sure how to describe exactly what they did. Tomorrow, I can get a picture and annotate it. That said, Tesla brought power from the meter side into the breaker side, but bypassed all the breakers and ran the power then to their switch 200A breaker. They then ran the power back to my main panel to the 200A breaker that trickles down to the house breakers. This was the same as having basically an empty main panel running to the switch that then ran to a second 200A panel with all the breakers in it. This setup is working perfectly for me. Everything is powered correctly. Also, SCE had a planned power outage yesterday in my area that lasted over 8 1/2 hours. I was electrically isolated from the grid and ran off the batteries (and solar) without experiencing any problems. Keith

This is close to an ideal easy situation for Tesla. Usually it requires a jurisdiction that will allow it (panel is being modified) and panel that is of the right type (e.g. a single 200A bus). I was hoping to end up in this situation but my 200A panel was a center fed model (basically 2 like 2 100A panels and the connection between the meter and load section was 2 100A legs.

arnold

 

[wwhitney]

A question for anyone getting an installation in the near future. If you have a chance please take a look at the stated capacity on the nameplate of one of the Powerwalls. It is located on the bottom of the left-hand side, behind the cover. I believe the cover comes off during installation to hook up the conduit, so that would be a convenient time to look at it.

In this photo from August, 2017, the name plate shows 13.2 kWh capacity: http://ulmo.solar/tesla/energy/powerwall/installation_in_progress/batteries/IMG_8140 Label.png This does not agree with the spec sheet, also from August, 2017, which states a usable capacity of 13.5 kWh. I'm curious if this discrepancy is still occurring.

Thanks,
Wayne

 

[MorrisonHiker]

We had a site survey over the weekend and found out that our first choice for installation of the Powerwalls wasn't allowed. We had originally chosen the shared wall between the garage and house. We found out that the Powerwalls cannot be installed on a wall which has "habitable" space behind it. Fortunately, we have a large garage and were able to choose another location. Also, there is a limit on how high they can be mounted since there is a switch located on the top of each Powerwall. IIRC, they won't mount them with the top higher than 74". We have a portable workbench along the new wall. Due to the workbench height and height of the Powerwalls, we'll have to move the bench to another location.

I just thought I would post here since I hadn't heard of these restrictions in previous posts or when talking with Tesla Energy before the site survey.

 

[Kren]

We had a site survey over the weekend and found out that our first choice for installation of the Powerwalls wasn't allowed. We had originally chosen the shared wall between the garage and house. We found out that the Powerwalls cannot be installed on a wall which has "habitable" space behind it. Fortunately, we have a large garage and were able to choose another location. Also, there is a limit on how high they can be mounted since there is a switch located on the top of each Powerwall. IIRC, they won't mount them with the top higher than 74". We have a portable workbench along the new wall. Due to the workbench height and height of the Powerwalls, we'll have to move the bench to another location.

I just thought I would post here since I hadn't heard of these restrictions in previous posts or when talking with Tesla Energy before the site survey.

. Also, for my install, the issue was they were getting to close to the gas meter. So installers did some last minute adjustments.

 

[wwhitney]

We found out that the Powerwalls cannot be installed on a wall which has "habitable" space behind it.

That's got to be a policy issue for Tesla, they don't want complaints about noise from the cooling fans being transferred to the living space. There's no technical or code issue with that location.

Also, there is a limit on how high they can be mounted since there is a switch located on the top of each Powerwall. IIRC, they won't mount them with the top higher than 74".

Good to know, I hadn't realized there was a switch at each unit, it must be behind the left side panel at the very top of that side. The NEC requirement is that the center of the switch handle be no more than 79" above the floor, so if Tesla is using 74" they are being a bit conservative.

Now the backup gateway, unless it has a main circuit breaker inside of it, is not subject to any NEC height limitations. Tesla may still have its own policies, though. I'm planning to have mine installed with the top about 8' off the ground to optimize the use of space in a small house.

Cheers, Wayne

 

[MorrisonHiker]

That's got to be a policy issue for Tesla, they don't want complaints about noise from the cooling fans being transferred to the living space. There's no technical or code issue with that location.


Good to know, I hadn't realized there was a switch at each unit, it must be behind the left side panel at the very top of that side. The NEC requirement is that the center of the switch handle be no more than 79" above the floor, so if Tesla is using 74" they are being a bit conservative.

Now the backup gateway, unless it has a main circuit breaker inside of it, is not subject to any NEC height limitations. Tesla may still have its own policies, though. I'm planning to have mine installed with the top about 8' off the ground to optimize the use of space in a small house.

Cheers, Wayne

I think he said 6'2" (74"), not 6'7" (79"). Either way, I'll ask when they come back out for the installation and post an update with the actual number they follow.

 

[SoundDaTrumpet]

That's got to be a policy issue for Tesla, they don't want complaints about noise from the cooling fans being transferred to the living space. There's no technical or code issue with that location.


Good to know, I hadn't realized there was a switch at each unit, it must be behind the left side panel at the very top of that side. The NEC requirement is that the center of the switch handle be no more than 79" above the floor, so if Tesla is using 74" they are being a bit conservative.

Now the backup gateway, unless it has a main circuit breaker inside of it, is not subject to any NEC height limitations. Tesla may still have its own policies, though. I'm planning to have mine installed with the top about 8' off the ground to optimize the use of space in a small house.

Cheers, Wayne

I am considering mounting high about a foot below the ceiling in the garage (there is living space above the garage). It is good to know the limitation with height. Does anyone know the vertical dimension for the switch on the side?

Initially I was planning for an outdoor double-stacked floor installation. The better half of me wants it inside the garage now considering how immaculate they looked at the showroom this past weekend. I personally noted the on/off switch on the side being too easy to get to. Given that my finished garage walls are empty, is an indoor location preferable?

It be great to get some input. Thanks.

 

[wwhitney]

Does anyone know the vertical dimension for the switch on the side?

I don't know, but there is this photo:

http://ulmo.solar/tesla/energy/powe...ess/batteries/IMG_8138 left cover off top.png

I don't see a switch, so I infer it must be in the erased area at the top. Or else it is not on the left side as I assumed. From various photos, it does not appear to be on top.

Cheers, Wayne

 

[MP3Mike]

I don't see a switch, so I infer it must be in the erased area at the top. Or else it is not on the left side as I assumed. From various photos, it does not appear to be on top.

It is on the right side according to page 6 of the manual: https://www.tesla.com/sites/default/files/pdfs/powerwall/powerwall_2_ac_owners_manual.pdf