Powerwall 2: Installation

[mongo]

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.

Progress!
Question: I'm only seeing two double pole breakers in the new panel, based on your description I expected to see two for PV plus one for PW (soon to be two, four total).
Powerline communication can't cross a transformer, other than that any conductive topology is good.

 

[mongo]

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

In general, or due to a >6 inch projection into the panelboard working space? (with the loose interpretation that it is equipment due to use for grounding 110.26(A)(3) is what I'm thinking of).
Reference for anyone interested.

 

[wwhitney]

(with the loose interpretation that it is equipment due to use for grounding 110.26(A)(3) is what I'm thinking of).

That's not an interpretation I'd buy. I'd say the hose bib should not extend beyond the face of the panel directly above it.

If the righthand panel had been placed 6" to the right, it would be OK, assuming neither vent hood nor the gate post extend beyond the face of the panel.

Cheers, Wayne

 

[mongo]

That's not an interpretation I'd buy. I'd say the hose bib should not extend beyond the face of the panel directly above it.

If the righthand panel had been placed 6" to the right, it would be OK, assuming neither vent hood nor the gate post extend beyond the face of the panel.

Cheers, Wayne

Yeah 3-6 would clear it, tight squeeze with vents, bib, gate, and gas meter...

Was curious on bib due to having one next to my main service disconnect, but it is behind the face.

 

[miimura]

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

I was actually more concerned that they left the required space between the gas service line and the Gateway. We discussed the issue before they started, so I assume they pulled out a measuring tape before they mounted the boxes.

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.

A different person contacted me today from the electrical contractor and said that he would be provisioning today. He asked for the e-mail used on my Tesla account and my WiFi credentials. The WiFi signal at that corner of the house is only so-so on 2.4Ghz and likely unusable on 5GHz. I did notice that the top of the Gateway has a plastic square gasketed section, likely to allow some wireless signal in and out. There is an Ethernet on the other side of the wall, so if necessary, I could provide a wired connection.

 

[miimura]

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

The picture was taken in the morning. That wall actually does get quite hot on a Summer afternoon since it is facing south-west. However, there was no other straight forward mounting location. I would have liked them to be stacked and installed inside the light well at the back of the house, but it would have required rigging to get the heavy batteries lowered down into the light well. As it is, they barely got them up the hill and mounted on the wall.

 

[Frankman60]

I was seeing the green moss on the ground so I thought it was perhaps north facing. I am trying to find a location that doesn’t get any sun but it has been a challenge. I know that the PWs are liquid cooled which is good, but how much inefficiency does that create? Does anyone have PWs in a location that gets a lot of sun in a warm climate? Do the internal fans spin up a lot and how much noise do they make? Does the app report the internal temperature of each PW, like my SMA inverters do?

The picture was taken in the morning. That wall actually does get quite hot on a Summer afternoon since it is facing south-west. However, there was no other straight forward mounting location. I would have liked them to be stacked and installed inside the light well at the back of the house, but it would have required rigging to get the heavy batteries lowered down into the light well. As it is, they barely got them up the hill and mounted on the wall.

 

[Bigtanuki]

What about this situation. I only plan to install one PW now, but may want to expand to two PWs in the future if the price decreases or other incentives are introduced. I understand if I want to stack two Powerwalls, they must be placed on the ground. In my situation I am only installing one PW now, and would prefer that it be mounted at least several inches off the ground on the side of my house (to keep rain runoff from touching the PW). This elevated wall mounting is fine for one PW but not if I want to add a second PW later. If I add a PW later, the first one that is already on the wall will need to be dropped several inches to the ground. My question is, is there a place to leave some excess wire in the PW or the gateway so this can be done without pulling new wire through the conduit? I assume that the metal conduit can be extended the few inches needed. Any thoughts on this?

I currently have 2 PWs and had them install wiring for a third. My units are stacked in the garage. I was fortunate enough to get enough referrals to get my third PW. The installing electrician indicated that the third unit should essentially be a"drop in" installation. I wanted 3 units to allow charging of my MS at 12kW rather than having to adjust the charge rate depending on whether I charged from grid or battery.

 

[markb1]

I currently have 2 PWs and had them install wiring for a third. My units are stacked in the garage. I was fortunate enough to get enough referrals to get my third PW. The installing electrician indicated that the third unit should essentially be a"drop in" installation. I wanted 3 units to allow charging of my MS at 12kW rather than having to adjust the charge rate depending on whether I charged from grid or battery.

You might be interesting in the discussion of the the 150% rule for net metering, which starts here: Powerwall 2: SGIP/Incentives

 

[SoundDaTrumpet]

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

Thanks for offering...

Tesla was able to resolve my questions.
1. Tesla doesn't support 400A backup load center yet. Even so, 400A backup load center aren't allowed on 200A service.
2. Loads on the backup load panel are pretty much limited to 175A, which is the next breaker size down from 200A. This accommodates 2 PW and 20A of solar backfeed on the new backup load panel.
3. Elaborated what a main panel upgrade ($2500) really is. It's a panel swap for me to get 25A extra. Not worth the money for me. If I ever run out of capacity I could just move my EV or AC units onto the service panel and downsize to a 150A breaker feeding the backup panel.

 

[arnolddeleon]

Today stucco repair finally happened. I'm super impressed by the quality of work (quick look at night). I was pleasantly surprised that they painted! They even painted the conduit.

So in summary, the actual crews that work on site have ranged from good to terrific. The coordination/design process has a lot of room for improvement.

arnold

 

[wang5150]

Finally!

 

[Musterion]

I started my Powerwall project with a reservation in Aug 2017 after getting several tips here. Thanks! I had previously booked a Swell installation but then canceled it after deciding the pricing was not good, among other objections I had about their inability to send me my signed paperwork, and ultimately went with Tesla. First site visit in Sep 2017. Then the project dropped completely off grid. 4 months later I got a phone message from Tesla with a cryptic message that I just got moved off the “generator hold” list. Congratulations! I called back and said I had no generator installed (unless you count solar as a generator), and got a “re-audit” at end of Jan 2018. In meantime I missed out on SGIP step 2 and now Tesla tells me:

1) If I went with normal residential install, they would use my original order date somehow but this might only get me to step 4, or worse. True? It seems impossible to estimate from the SGIP pages.

2) My original plan of 2 powerwalls in insufficient due to loads and they want to only certify a 3-PW solution. We went back and forth on manual load control etc. but do have a point about some of my high-amperage loads (which I had planned to shut down during power failure). I also pointed out a 3-PW solution goes beyond the residential SGIP requirements of 10kW. Aha, they then said...

3) For the first time, they said Tesla now will file commercial SGIP applications for residential install and they just got approval to file on my behalf for this project, allowing me to go beyond 2 powerwalls and still use SGIP. The trade-off is a lower rebate (29 cents / W I believe), but it can be applied to all the equipment used. In fact, my average load and size of solar system justify going up to 4 powerwalls. And it was pointed out that despite the delay, this was a good thing that came out of it (they did apologize for the delay, which was apparently caused by some very bad internal communication that never reached me).

Since 2 powerwalls was going to be a stretch, I’m enticed by being able to install a larger system in which I don’t have to manually juggle loads (my config would be a “whole-house backup” install) and still apply state rebates, plus still take advantage of fed ITC.

Any feedback on any of this?? I finally got a quote and it has very reasonable install costs, but I have to decide on committing and whether to push for 2 powerwalls and the normal residential SGIP, or try for the new Tesla-aided commercial install with more powerwalls and a better overall system.

 

[wwhitney]

The trade-off is a lower rebate (29 cents / W I believe), but it can be applied to all the equipment used.

The lower rebate for Large Storage SGIP is only if you are claiming the ITC on the Powerwalls. If your total Powerwall cost is cheap enough, you are better off skipping the ITC. In this post I calculated that the breakeven is presently $7,617 per Powerwall.

Cheers, Wayne

 

[arnolddeleon]

The lower rebate for Large Storage SGIP is only if you are claiming the ITC on the Powerwalls. If your total Powerwall cost is cheap enough, you are better off skipping the ITC. In this post I calculated that the breakeven is presently $7,617 per Powerwall.

Cheers, Wayne

I kinda wished I understood this when Tesla was proposing that I get 3 Powerwalls instead of the 2. I didn't know at that time that I could switch to Large Storage SGIP. I thought the 3rd one would be a full price so I stayed with 2. I initially thought that over 26kWh would feel like a lot for backup But it doesn't feel so much in the winter when the batteries are cycling (I'm using 70% reserved) for self-consumption. I know that for SGIP I don't really need to cycle in the winter, 52 discharges over that year shouldn't hard. I'm testing the system right now to get a feel for how it behaves. The slight surprise is that since the house is fully backed it is easy to not realize that the house is on backup power so a large load like the heat pump or car charger can suck down the batteries. I haven't tested how well the app alarm will notify me. What I will have to figure is how to come up with whole house alert for this.

arnold

 

[eml2]

What I will have to figure is how to come up with whole house alert for this.

I have a whole house backup. I also have a NAS that is powered by Tripp UPS, which will send me an e-mail when there is a power lost. Even though the PW switches over pretty quickly (clocks on the appliances do not reset), the UPS is sensitive enough that it will notice the power drop and thus email me the alert.

 

[Frankman60]

I have been thinking about how I could be notified when the house switches over to PW during a grid outage for the same reasons that arnolddeleon mentioned. If there is a grid outage while I’m sleeping and my Model S is charging, the PW will get drained pretty quickly and I would rather just stop charging the car when the grid goes down. But if the Model S is charging at 40 amps, would that be enough kWs to overload the 2 PWs and force the PWs off line because it exceeds the 10 kW capacity of 2 PWs? It would actually be more kWs than just the car charger because rest of the house load would also be on the PWs.

I don’t believe that the Tesla app pushes notifications when a grid outage occurs. The Tripp UPS that eml2 mentioned seems good, but is there a non-UPS product that could detect the brief (a few milliseconds) power interruption and push a notification? Ideally the Tesla app should do this because doesn’t it record the power interruption in a log?

 

[wwhitney]

Doesn't the app issues notifications now on power outage?

Because of the possibility of an outage overnight while an EV is charging, I don't think it is a good idea to backup up EVSEs by default. With some extra EVSE-specific wiring, one could disable the EVSE on power outage, with a manual override to re-enable it while on Powerwalls, if desired.

My plan is to use a manual transfer switch (actually just mechanically interlocked breakers) to allow powering my non-critical loads panel either from the grid, or from the Powerwalls. I'll default to powering it from the grid; if there is an extended outage and I want to run some of those loads, I can do that easily under manual control.

Cheers, Wayne

 

[Frankman60]

Hopefully someone with an installed PW can jump in here and let us know if the Tesla app will push a notification during a grid outage.

I wanted to exclude the EVSE from the whole home backup to but to do that the contractor said that it would require another subpanel because no circuits could be left in the original meter/panel. I don’t really have room on the wall for another panel just for the EVSE circuit and it was going to cost several hundred dollars more.

Doesn't the app issues notifications now on power outage?

Because of the possibility of an outage overnight while an EV is charging, I don't think it is a good idea to backup up EVSEs by default. With some extra EVSE-specific wiring, one could disable the EVSE on power outage, with a manual override to re-enable it while on Powerwalls, if desired.

My plan is to use a manual transfer switch (actually just mechanically interlocked breakers) to allow powering my non-critical loads panel either from the grid, or from the Powerwalls. I'll default to powering it from the grid; if there is an extended outage and I want to run some of those loads, I can do that easily under manual control.

Cheers, Wayne

 

[wwhitney]

Hopefully someone with an installed PW can jump in here and let us know if the Tesla app will push a notification during a grid outage.

People here have reported that the latest app does. At least on iOS, it generates APN (Apple Push Notifications). I'm still unclear on Android.

I wanted to exclude the EVSE from the whole home backup to but to do that the contractor said that it would require another subpanel because no circuits could be left in the original meter/panel.

I take it you currently have a 200A combo meter/main with a 200A bus, and the plan is to have only one distribution breaker that panel, a 200A breaker to feed the new equipment? Then your contractor is correct, if you wanted to leave a 50A breaker in that panel for your 40A EVSE, then you'd have to use a 150A breaker to feed your new equipment to protect the bus. Or if you don't have solar, you could change the main breaker in that panel to a 175A breaker, then you can put as many breakers as you want in your main panel (without backup power), via the 120% rule: 175 + 30 * 2 < 120% * 200.

Otherwise, you would need a separate panel for the EVSE breaker, and this panel would be supplied via a feeder tap on the feeder from your meter/main to the Backup Gateway. That panel could be as small as a 2 space panel, like this one:

Murray 60 Amp 2-Space 4-Circuit Surface Mount Main Lug Load Center-LC002GSU - The Home Depot

Actually you'd probably want a physically somewhat bigger one, to provide space for the insulated mechanical connectors used for the tap. But you only need a 2 space, main lug panel with a single 50 amp 2 pole breaker: you can backfeed the breaker (meaning it needs a hold down) with the feeder tap, and then take your EVSE circuit off of the main lugs (using them as subfeed lugs).

It would still cost you a few hundred dollars to do that. You might be able to devise an alternative method to shut off you EVSE during a power outage for a comparable cost, with the added ability to manually enable EVSE charging off the Powerwalls if required.

Cheers, Wayne