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4 kW Tesla solar install (with existing solar) and Powerwall addition and what I learned

h2ofun

Active Member
Aug 11, 2020
1,653
271
auburn, ca
It wouldn't be surprising to see the behaviour that you saw. Tesla also just finished my install (an addition to existing solar and Powerwalls). The new Powerwall did not immediately start charging when it was added to the group even though I had solar. All the solar was being consumed by the house (and I suspect would have gone to the grid if I had surplus).


We did a grid off test and then after that the Powerwalls (old and new) started charging. Now the Powerwalls are consuming all the solar being produced (currently in off peak) presumably to bank for the upcoming part peak window.
so how much solar/pw did you have, and what did you change to? What was the driver for the upgrades?

(moderator note: this post was moved from another thread, and placed in this thread because it answers the question. Because of how the forum software works, since the date / timestamp of this post is earlier than the OPs post in the thread, it appears first).
 
Last edited by a moderator:

arnolddeleon

Supporting Member
Jul 21, 2012
700
775
SF Bay Area
Got call yesterday asking if I wanted to get my 4kW PV and Powerwall install tomorrow (today). I said yes and they just finished and here are some things I learned.

Background (existing systems)

19 year old system
128 BP-585 modules (85 watt STC rating)
3 Outback GVFX-3648 (3.6kW)

12 year old system
12 Kyocera KD205GX-LP (205 watt STC, 180 watt PTC)
1 Xantrex GT2.8-NA 240/208 (2.8kW)

3 year old system
2 Tesla Powerwall 2
Gateway 1
Whole house backup
Dedicated generation panel

Things I learned

Powerwall installs:

The new restrictions in Santa Clara county CA and what many of the cities (Cupertino in my case) have adopted are annoying. I forgot to take a picture of the sheet that the installers showed me. All of these I've heard about ins some form or another. Here the ones I could remember:

Can't stack (double deep), e.g. my existing system would not be allowed
Can't be within 5' of property line
Can't be with 3' of window or that leads to house
Can't install inside of garage

I had hoped that would have been a small matter of putting a 3rd one on the existing stack, also no joy. So my new powerwall is on outside wall of my garage about 6' from my front door. I now have Powerwalls on two outside walls of my garage. I also will need some forgiveness from my wife for taking out a plant to get access to the space where the Powerwall #3 went. I'm planning on planting a replacement.

Tesla Inverter:

Minimum string length apparently 5.
Rapid shutdown is achieved with an active part in the modules (@nwdiver , I think you were wondering about this) that is present in every 3rd module. The installer called it a "mick" (MIC?).
The inverter has a fan.
Commissioning is how others have described it, from an app connecting to a local WiFi network shortly after power up.
There is a hardwired Ethernet port but I wasn't prepared with a cable.
Apparently an external disconnect is still required in my area. I thought this was no longer the case but I might have fallen into the line of site rules. The new inverter is on the other side of the fence from my main panel.

PV panels:

They look real good (from the ground). Skirts installed I think all around (can't see the top), definitely side and bottom.

Scheduling and Install

As I mentioned, my install was originally for May 28th. I assumed when they called me yesterday that it was because of a cancellation. That doesn't appear to be the case. The two teams (PV and storage) are from Southern CA and were called up to assist here. It looks like they work about a week before going home.

I think they caught a break with my install. I was able to figure out some options that made the install go smoother. There were a couple of things that I would have had had them do differently had I been able to spend all my attention on them (I was doing work at the same time). I wish I had a more detailed plan before they came so I could have been better prepared to make suggestions on things like conduit routing.

They move fast. I think there 3 people on solar crew and 2 on the storage crew.

In the Tesla app I could see the 3rd Powerwall as soon as they "commissioned" it. Not surprising. I also can't see the new solar in the app yet, I'm told that will come after PTO, also not surprising.

They painted the conduit. If you have matching paint be ready, I didn't have any. Someone on the install team did an eyeball match with a paint kit they apparently travel with, it looks pretty good to me.

They generate a punch of small things for the inspection person to handle. For example, they were missing a nut to bond the inverter door.


Photo Album:


Note I know that some of the photos show the password for the solar inverter used during setup. If you are physically close enough to the inverter for that information to be useful then you are physically close enough to get it.

Sharp eyed viewers might also not an incorrectly sized breaker, that's on the punch list, they didn't have one on the truck.
 
Last edited:

h2ofun

Active Member
Aug 11, 2020
1,653
271
auburn, ca
Got call yesterday asking if I wanted to get my 4kW PV and Powerwall install tomorrow (today). I said yes and they just finished and here are some things I learned.

Background (existing systems)

19 year old system
128 BP-585 modules (85 watt STC rating)
3 Outback GVFX-3648 (3.6kW)

12 year old system
12 Kyocera KD205GX-LP (205 watt STC, 180 watt PTC)
1 Xantrex GT2.8-NA 240/208 (2.8kW)

3 year old system
2 Tesla Powerwall 2
Gateway 1
Whole house backup
Dedicated generation panel

Things I learned

Powerwall installs:

The new restrictions in Santa Clara county CA and what many of the cities (Cupertino in my case) have adopted are annoying. I forgot to take a picture of the sheet that the installers showed me. All of these I've heard about ins some form or another. Here the ones I could remember:

Can't stack (double deep), e.g. my existing system would not be allowed
Can't be within 5' of property line
Can't be with 3' of window or that leads to house
Can't install inside of garage

I had hoped that would have been a small matter of putting a 3rd one on the existing stack, also no joy. So my new powerwall is on outside wall of my garage about 6' from my front door. I now have Powerwalls on two outside walls of my garage. I also will need some forgiveness from my wife for taking out a plant to get access to the space where the Powerwall #3 went. I'm planning on planting a replacement.

Tesla Inverter:

Minimum string length apparently 5.
Rapid shutdown is achieved with an active part in the modules (@nwdiver , I think you were wondering about this) that is present in every 3rd module. The installer called it a "mick" (MIC?).
The inverter has a fan.
Commissioning is how others have described it, from an app connecting to a local WiFi network shortly after power up.
There is a hardwired Ethernet port but I wasn't prepared with a cable.
Apparently an external disconnect is still required in my area. I thought this was no longer the case but I might have fallen into the line of site rules. The new inverter is on the other side of the fence from my main panel.

PV panels:

They look real good (from the ground). Skirts installed I think all around (can't see the top), definitely side and bottom.

Scheduling and Install

As I mentioned, my install was originally for May 28th. I assumed when they called me yesterday that it was because of a cancellation. That doesn't appear to be the case. The two teams (PV and storage) are from Southern CA and were called up to assist here. It looks like they work about a week before going home.

I think they caught a break with my install. I was able to figure out some options that made the install go smoother. There were a couple of things that I would have had had them do differently had I been able to spend all my attention on them (I was doing work at the same time). I wish I had a more detailed plan before they came so I could have been better prepared to make suggestions on things like conduit routing.

They move fast. I think there 3 people on solar crew and 2 on the storage crew.

In the Tesla app I could see the 3rd Powerwall as soon as they "commissioned" it. Not surprising. I also can't see the new solar in the app yet, I'm told that will come after PTO, also not surprising.

They painted the conduit. If you have matching paint be ready, I didn't have any. Someone on the install team did an eyeball match with a paint kit they apparently travel with, it looks pretty good to me.

They generate a punch of small things for the inspection person to handle. For example, they were missing a nut to bond the inverter door.
You have to update your signature.

Got pictures?

So you cannot stack even 2 levels now? No garage which is where so many seem to put them?

Any technical reasons you went with more solar and another PW?

Since recommended minimum is 4K per PW, you look good.

What TOU plan are you on? Does the 3rd PW force you to NEM2-MT? or nem2-PS?
 

arnolddeleon

Supporting Member
Jul 21, 2012
700
775
SF Bay Area
so how much solar/pw did you have, and what did you change to? What was the driver for the upgrades?


The new total is about 17 kW of solar with 3 Powerwalls. The solar total is very misleading. The ratings I report for the old systems are the standard test conditions (STC) numbers. They are 19 and 12 years old so they have degraded and the old inverters were not as efficient. The new solar is also on the "wrong" roof (I'm out of space on the existing one) so it will never produce peak power. I suspect my production is comparable to a brand new, reasonably south, 12 kW install.

I'm working towards killing my natural gas usage and I wanted to add solar before the California Public Utilities Commission (CPUC) totally gives in to the Investor Owned Utilities (IOUs) and totally borks solar. Usually we get a small bone tossed at us with legacy systems (e.g. allowed to operate with old rules for a period of time).
 

arnolddeleon

Supporting Member
Jul 21, 2012
700
775
SF Bay Area
You have to update your signature.

Got pictures?

So you cannot stack even 2 levels now? No garage which is where so many seem to put them?

Any technical reasons you went with more solar and another PW?

Since recommended minimum is 4K per PW, you look good.

What TOU plan are you on? Does the 3rd PW force you to NEM2-MT? or nem2-PS?

The Powerwall restrictions are really bad. I think most folks have an outside garage wall that is exactly 5' away from their property/fence line. That is unusable with the current rules. I also believe Tesla doesn't recommend being installed on wall to the house because they do make some noise and if attached to the wall that could couple the noise.

I'm currently squeezing out the last dregs of E-6 with PG&E

I was already on NEM2-MT. I'm assuming it will stay that way but who knows.

Working on photos.
 

h2ofun

Active Member
Aug 11, 2020
1,653
271
auburn, ca
The new total is about 17 kW of solar with 3 Powerwalls. The solar total is very misleading. The ratings I report for the old systems are the standard test conditions (STC) numbers. They are 19 and 12 years old so they have degraded and the old inverters were not as efficient. The new solar is also on the "wrong" roof (I'm out of space on the existing one) so it will never produce peak power. I suspect my production is comparable to a brand new, reasonably south, 12 kW install.

I'm working towards killing my natural gas usage and I wanted to add solar before the California Public Utilities Commission (CPUC) totally gives in to the Investor Owned Utilities (IOUs) and totally borks solar. Usually we get a small bone tossed at us with legacy systems (e.g. allowed to operate with old rules for a period of time).
This is why I am looking at could I put on more solar and max my usable roof also before NEM3. I wanted 7 batteries but the SGIP rules would not allow. Oh well, 5 is better than none
 

BGbreeder

Member
Jun 19, 2020
145
81
Bay Area
@arnolddeleon Great photos! Thanks for sharing the and the install saga. My installer gave up on mounting the Powerwalls on the house due to the 36" separation rule. We would have had something like 65' of conduit to make it happen.

All the best,

BG
 

h2ofun

Active Member
Aug 11, 2020
1,653
271
auburn, ca
Got call yesterday asking if I wanted to get my 4kW PV and Powerwall install tomorrow (today). I said yes and they just finished and here are some things I learned.

Background (existing systems)

19 year old system
128 BP-585 modules (85 watt STC rating)
3 Outback GVFX-3648 (3.6kW)

12 year old system
12 Kyocera KD205GX-LP (205 watt STC, 180 watt PTC)
1 Xantrex GT2.8-NA 240/208 (2.8kW)

3 year old system
2 Tesla Powerwall 2
Gateway 1
Whole house backup
Dedicated generation panel

Things I learned

Powerwall installs:

The new restrictions in Santa Clara county CA and what many of the cities (Cupertino in my case) have adopted are annoying. I forgot to take a picture of the sheet that the installers showed me. All of these I've heard about ins some form or another. Here the ones I could remember:

Can't stack (double deep), e.g. my existing system would not be allowed
Can't be within 5' of property line
Can't be with 3' of window or that leads to house
Can't install inside of garage

I had hoped that would have been a small matter of putting a 3rd one on the existing stack, also no joy. So my new powerwall is on outside wall of my garage about 6' from my front door. I now have Powerwalls on two outside walls of my garage. I also will need some forgiveness from my wife for taking out a plant to get access to the space where the Powerwall #3 went. I'm planning on planting a replacement.

Tesla Inverter:

Minimum string length apparently 5.
Rapid shutdown is achieved with an active part in the modules (@nwdiver , I think you were wondering about this) that is present in every 3rd module. The installer called it a "mick" (MIC?).
The inverter has a fan.
Commissioning is how others have described it, from an app connecting to a local WiFi network shortly after power up.
There is a hardwired Ethernet port but I wasn't prepared with a cable.
Apparently an external disconnect is still required in my area. I thought this was no longer the case but I might have fallen into the line of site rules. The new inverter is on the other side of the fence from my main panel.

PV panels:

They look real good (from the ground). Skirts installed I think all around (can't see the top), definitely side and bottom.

Scheduling and Install

As I mentioned, my install was originally for May 28th. I assumed when they called me yesterday that it was because of a cancellation. That doesn't appear to be the case. The two teams (PV and storage) are from Southern CA and were called up to assist here. It looks like they work about a week before going home.

I think they caught a break with my install. I was able to figure out some options that made the install go smoother. There were a couple of things that I would have had had them do differently had I been able to spend all my attention on them (I was doing work at the same time). I wish I had a more detailed plan before they came so I could have been better prepared to make suggestions on things like conduit routing.

They move fast. I think there 3 people on solar crew and 2 on the storage crew.

In the Tesla app I could see the 3rd Powerwall as soon as they "commissioned" it. Not surprising. I also can't see the new solar in the app yet, I'm told that will come after PTO, also not surprising.

They painted the conduit. If you have matching paint be ready, I didn't have any. Someone on the install team did an eyeball match with a paint kit they apparently travel with, it looks pretty good to me.

They generate a punch of small things for the inspection person to handle. For example, they were missing a nut to bond the inverter door.


Photo Album:


Note I know that some of the photos show the password for the solar inverter used during setup. If you are physically close enough to the inverter for that information to be useful then you are physically close enough to get it.

Sharp eyed viewers might also not an incorrectly sized breaker, that's on the punch list, they didn't have one on the truck.
Not sure my wife would be happy with the PW at our front door. :(
 
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Flyguy

Member
Aug 17, 2017
293
165
94062
Thanks for the write-up! Assuming the new 4kw system came with gateway2, do the other systems go through that as well now, or run independently in parallel to each other?
 

arnolddeleon

Supporting Member
Jul 21, 2012
700
775
SF Bay Area
Thanks for the write-up! Assuming the new 4kw system came with gateway2, do the other systems go through that as well now, or run independently in parallel to each other?

Ah yes, I forgot to address in the original write up. I was able to get Tesla to reduce the price by the cost of a gateway because I didn't need another gateway. This had to go to design review and was obviously approved. The crew did come with a gateway (presumably a 2) but we didn't install it. They also had a load panel with them, also not needed. They also had a Sure Start but again I also didn't need that.

One of the reasons that install was pretty easy is that I already had a dedicated generation panel so the new solar and Powerwall just needed to be landed there. I saw them open the existing Powerwalls so I think there might be some wiring done for the controls for that.
 

jboy210

Supporting Member
Dec 2, 2016
4,849
2,982
Northern California
The new total is about 17 kW of solar with 3 Powerwalls. The solar total is very misleading. The ratings I report for the old systems are the standard test conditions (STC) numbers. They are 19 and 12 years old so they have degraded and the old inverters were not as efficient. The new solar is also on the "wrong" roof (I'm out of space on the existing one) so it will never produce peak power. I suspect my production is comparable to a brand new, reasonably south, 12 kW install.

I'm working towards killing my natural gas usage and I wanted to add solar before the California Public Utilities Commission (CPUC) totally gives in to the Investor Owned Utilities (IOUs) and totally borks solar. Usually we get a small bone tossed at us with legacy systems (e.g. allowed to operate with old rules for a period of time).
Just curious, but had you considered swapping out the old panels with new higher yield panels? My neighbors just replaced their 15-year-old panels.
 
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Flyguy

Member
Aug 17, 2017
293
165
94062
Ah yes, I forgot to address in the original write up. I was able to get Tesla to reduce the price by the cost of a gateway because I didn't need another gateway. This had to go to design review and was obviously approved. The crew did come with a gateway (presumably a 2) but we didn't install it. They also had a load panel with them, also not needed. They also had a Sure Start but again I also didn't need that.

One of the reasons that install was pretty easy is that I already had a dedicated generation panel so the new solar and Powerwall just needed to be landed there. I saw them open the existing Powerwalls so I think there might be some wiring done for the controls for that.
Thanks. We currently have 6.9kW system w/Powerwall and gateway 2 installed. Prices are so good was thinking of adding a 4kw Tesla system. Sounds like they could literally just plug the panels right into the existing system. Did you ask for any price reduction considering there was no other hardware needed?
 

arnolddeleon

Supporting Member
Jul 21, 2012
700
775
SF Bay Area
Thanks. We currently have 6.9kW system w/Powerwall and gateway 2 installed. Prices are so good was thinking of adding a 4kw Tesla system. Sounds like they could literally just plug the panels right into the existing system. Did you ask for any price reduction considering there was no other hardware needed?

I got a price reduction on the Powerwall, which was pretty much the cost of the gateway 2. That was easy to justify because there was equipment that clearly was not going to be used. As I noted in my original write up, the installers/Tesla got off lucky with my install. I'm sure they spent less time that they budgeted. I'm good with that because I knew overall I was still getting bargain because the cost was lower than if I had a full concierge sales team that would have quoted a more "exact" installation price adjusted for the complexity of the job. I like the Tesla pricing model.

On the solar side it was a completely independent system from my two other existing solar systems. The only really easy part was I already had a generation panel so they could install without causing any outages (never lost power yesterday). They probably needed to do slightly more work because I had so much existing equipment to route around. So, all in, a wash.

If you have a Tesla Inverter for your existing solar then they could potentially just add panels to your existing inverter although if you look at how they price things, it is mostly on the install, so any cost reduction on not having to add an inverter is not going to be huge. Don't forget that you can get a self referral credit and discount.
 
Last edited:

arnolddeleon

Supporting Member
Jul 21, 2012
700
775
SF Bay Area
Just curious, but had you considered swapping out the old panels with new higher yield panels? My neighbors just replaced their 15-year-old panels.
Yes, I did. The problem is my existing racking that is in place is not very compatible with modern panels. I also wouldn't be able to install new panels in the same way, if you saw the picture I posted of the street view of the house you can see that I have panels running all the way to the ridge line and to the edges.

I actually went through a replacement situation in another house about six years ago. The panels started failing prematurely and the manufacturer had exited the solar business so I couldn't get exact replacements. The manufacturer ended up offering me a buyout (fraction of what a paid for the system). I took the money and ordered a replacement from Solar City. I managed to convince the project manager to reuse my existing mounts and racking. However after the contracts were signed the Solar City lawyers said no. What they offered to do (at their cost because I had a contract) was to hire a roofer to remove my old mounting system, to "restore the roof" then they installed their standard system over that. The city of Sunnyvale refused to pass the inspection because it didn't meet the just emerging setback standards. Solar City came out, rearranged things and had to remove a few panels to make it pass. Because the system got smaller I got partial refund.

I would love a solar roof, however I installed a 50 year roof 20 years ago so it's kinda hard to justify a complete reroof.
 
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