Tesla 4.8kW + 2x PW Expansion

[jsurpless]

I have an existing 6kW solar system that Tesla is expanding upon with a 4.8kW + 2x PW this coming Monday.

As I understand it, Tesla has some mode of operation that allows you to use your system w/ PW to some extent prior to PTO.

Will that work for me with an expansion system (and this no PW+)?

 

[Rocket_man]

I have an existing 6kW solar system that Tesla is expanding upon with a 4.8kW + 2x PW this coming Monday.

As I understand it, Tesla has some mode of operation that allows you to use your system w/ PW to some extent prior to PTO.

Will that work for me with an expansion system (and this no PW+)?

I'm not 100% sure, but I think the key to that working is the Gateway 2. Do you have GW2? My newly installed system (two PW+'s and GW2) allowed me to use solar as soon as it was installed. I could run directly off the panels, the panels could charge the batteries, I just could not export. I'm still before PTO but since install I have been 97% self powered. So once the batteries are at 100%, the solar will be throttled to only what the house uses. Then at night I use the PWs and grid until solar production resumes in the morning.

 

[dailo]

It did for me. Make sure they add a Neurio to monitor your existing system, otherwise the system won’t work correctly and the stats in the app will be wrong. Only thing is your existing system will continue to export, which you already have PTO for so shouldn’t be an issue.

 

[jrweiss98020]

Just close all the breakers that control the PV and PW, and open the breaker between the grid and the Gateway to simulate a grid outage. PV+PW should take over.

 

[arnolddeleon]

You presumably already have a net metering agreement. So are you asking if there is a configuration that Tesla will let you turn on the your new system and limit your export to only be the old system? Does each PV system a utility accessible generation meter? Would the utility be able to tell which system generated/exported the power?

 

[jsurpless]

I'm not 100% sure, but I think the key to that working is the Gateway 2. Do you have GW2? My newly installed system (two PW+'s and GW2) allowed me to use solar as soon as it was installed. I could run directly off the panels, the panels could charge the batteries, I just could not export. I'm still before PTO but since install I have been 97% self powered. So once the batteries are at 100%, the solar will be throttled to only what the house uses. Then at night I use the PWs and grid until solar production resumes in the morning.

System's not installed yet (tomorrow) so I imagine that I'll get a Gateway 2? Does solar get throttled (i.e, 90%., 80%, etc) or just turned on/off when PWs are full if power's out?

It did for me. Make sure they add a Neurio to monitor your existing system, otherwise the system won’t work correctly and the stats in the app will be wrong. Only thing is your existing system will continue to export, which you already have PTO for so shouldn’t be an issue.

Good suggestion, thanks! I also need to make sure that they install soft starter for my A/C units.

You presumably already have a net metering agreement. So are you asking if there is a configuration that Tesla will let you turn on the your new system and limit your export to only be the old system? Does each PV system a utility accessible generation meter? Would the utility be able to tell which system generated/exported the power?

Yes, I have net metering on my existing system. And yes, I am asking if I could somehow prioritize the new system so that it charges the PWs (and maybe limits production to current house use) so that I can use it in the time before I get PTO.

Yes, I believe that there will be separate production meter for each system, I believe. Not sure how exactly utility would tell what the source of exported power is

 

[Rocket_man]

It throttled output to match the house demand. Sometimes it will draw from the PW, but not from the grid unless the PW's go below the reserve.

So during the day, as soon at the PW's hit 100% the solar production drops.

 

[Jedi2155]

You have a similar situation with me where I added a Tesla array + 2 PW's to an existing home with an existing array. On the Power Gateway 2 (PG2), there is space for 6 breakers, or 2x3 240v breakers. What will happen is the following:

PG2 will contain the following:

1. Breaker for existing PV array
2. Breaker for AC PW2
3. Breaker for AC PW+ (which will include the 3.8 kW Tesla Solar Inverter)

Your entire home will be behind the PG2 so it will know how much load your home is consuming. The app will control the PW/Tesla Solar Inverter operation into a Self-Consumption mode, where it will curtail the Tesla Solar generation to limit it to the home loads.

1. Due to the way it'll be setup electrically, the existing PV, will continue to generate and potentially export during the solar day.
2. At night when there is no solar, the PW will discharge to keep your home load to 0.
3. During the day again, if Solar + Tesla Solar > home loads, then it will use the excess PV to charge your PW.
4. If the PW hits 100% during the day before your PTO, then the Telsa solar will curtail itself to 0 unless Home Loads exceed Tesla PV + existing PV, and then the PW will kick on to discharge to keep your home load to 0. Then will recharge the PW as needed with PV only production.

Hope that helps!

 

[jsurpless]

You have a similar situation with me where I added a Tesla array + 2 PW's to an existing home with an existing array. On the Power Gateway 2 (PG2), there is space for 6 breakers, or 2x3 240v breakers. What will happen is the following:

PG2 will contain the following:

1. Breaker for existing PV array
2. Breaker for AC PW2
3. Breaker for AC PW+ (which will include the 3.8 kW Tesla Solar Inverter)

Your entire home will be behind the PG2 so it will know how much load your home is consuming. The app will control the PW/Tesla Solar Inverter operation into a Self-Consumption mode, where it will curtail the Tesla Solar generation to limit it to the home loads.

1. Due to the way it'll be setup electrically, the existing PV, will continue to generate and potentially export during the solar day.
2. At night when there is no solar, the PW will discharge to keep your home load to 0.
3. During the day again, if Solar + Tesla Solar > home loads, then it will use the excess PV to charge your PW.
4. If the PW hits 100% during the day before your PTO, then the Telsa solar will curtail itself to 0 unless Home Loads exceed Tesla PV + existing PV, and then the PW will kick on to discharge to keep your home load to 0. Then will recharge the PW as needed with PV only production.

Hope that helps!

Hi

Thanks for the detailed reply!

Alas, I'm not sure if it'll apply to me since i don't have a PW+; I asked for one but was told that they couldn't be used when integrating with an existing solar system. It seems that this was inaccurate :-( - too bad, although probably won't matter much in the long term.

My PG2 has one breaker for existing solar, one for tesla solar and one for a combined PW feed from another junction box in the garage near the PWs.

 

[Jedi2155]

Hi

Thanks for the detailed reply!

Alas, I'm not sure if it'll apply to me since i don't have a PW+; I asked for one but was told that they couldn't be used when integrating with an existing solar system. It seems that this was inaccurate :-( - too bad, although probably won't matter much in the long term.

My PG2 has one breaker for existing solar, one for tesla solar and one for a combined PW feed from another junction box in the garage near the PWs.

What's the size of your existing home loads? I believe the difference between PW2 and PW+ is just the output power, it should work the same way whether its PW+ or PW2. I had a 200A main panel, and a PW+ would be needed to backup my 5 ton home AC unit while a standard PW would not be powerful enough.

The other determining factor why they put a PW+ instead of a PW2 is because I ordered 9.6 kW (7.6 kW Inverter) of solar rather than 4.8.

 

[jsurpless]

Yeah, I don't know...

I tried to get them to give me a PW+ for these various reason but they were quite adamant that it wasn't possible in conjunction with an existing system.

So my install is finished as of yesterday afternoon (two days, not bad). The installers did a fantastic job, running conduit in the walls and generally just keeping everything out of sight as much as possible.

Here's how it ended up - backup gateway and inverter are in the basement, powerwalls in the garage (due to fire closet requirement in MA). Did have quite the surprise on Monday when they showed up and told me about the bollards required in the garage! Apparently, some new code in MA as of December 2021.

 

[miimura]

The Powewalls are completely above the bollards. If they could just mount them that high, what's the point of the bollards? I can understand the bollards if the Powerwalls are floor mounted or at least close to "bumper height".

 

[jsurpless]

If they were floor mounted then they would have been ~3 ft out from the PWs (and seriously impacting parking).

I always wanted to mount them above ground (to allow stuff underneath) and I asked that very question about the bollards. It's what the town wanted to meet MA code.

 

[miimura]

If they were floor mounted then they would have been ~3 ft out from the PWs (and seriously impacting parking).

I always wanted to mount them above ground (to allow stuff underneath) and I asked that very question about the bollards. It's what the town wanted to meet MA code.

In that case, what you got appears to be the most minimally invasive bollard implementation possible.

 

[jsurpless]

In that case, what you got appears to be the most minimally invasive bollard implementation possible.

Yup, I'm reasonably happy with it... it'd have been better with everything in the basement but alas, that wasn't an option.

 

[Jedi2155]

I wonder if the reason you didn't get a Powerwall+ in your case is due to the fact that your inverters and powerwalls are in separate areas. The PW+ has to be next to where the solar install is. The only real benefit of the PW+ over the PW2 greater backup power output during whole house backup. In your case that is limited to 5.8 kW x 2 instead of 9.6 kW/7 kW + 5.8 kW during backup. It means nothing during on-grid operation, but only makes a difference during backup operation.

Also the bollard thing is interesting since I heard from my CA install that several California cities are also requiring it.

 

[holeydonut]

View attachment 803099

Oooooo bollards.

 

[jsurpless]

I wonder if the reason you didn't get a Powerwall+ in your case is due to the fact that your inverters and powerwalls are in separate areas. The PW+ has to be next to where the solar install is. The only real benefit of the PW+ over the PW2 greater backup power output during whole house backup. In your case that is limited to 5.8 kW x 2 instead of 9.6 kW/7 kW + 5.8 kW during backup. It means nothing during on-grid operation, but only makes a difference during backup operation.

Also the bollard thing is interesting since I heard from my CA install that several California cities are also requiring it.

Perhaps, although I believe that they said it wasn't possible before they moved them to the garage. The whole design process was an ordeal because of the disconnect btw me, advisor and designer. I think that the design team is just confused at times, they insisted the inverter needed to be outside and the installers put in the basement so who knows...

 

[Jedi2155]

Perhaps, although I believe that they said it wasn't possible before they moved them to the garage. The whole design process was an ordeal because of the disconnect btw me, advisor and designer. I think that the design team is just confused at times, they insisted the inverter needed to be outside and the installers put in the basement so who knows...

I had a similar scenario between the design team and installers. Design team no secondary panel was needed (I was thinking I could use my existing sub-panel) but the installers insisted on moving everything to a new subpanel (Main Panel -> Tesla Gateway -> New Tesla Subpanel -> Existing SubPanel). Originally I was thinking it was (Main Panel -> Tesla Gateway -> Existing Sub Panel).