System expansion after installation

[lensovet]

We had a 4.8 kW system installed with PW+ (including gateway and integrated inverter) a year ago.

Since then our usage pattern has changed such that it would make a lot more sense to expand the system to have another 2.4 kW installed.

It seems crazy to me that Tesla won’t do this and insists on a completely separate system. I get that they might not want to touch something installed a decade ago by another installer, but this is a project which they designed and installed themselves less than a year ago. Isn’t it kind of wasteful to install a whole separate system instead of integrating into the existing inverter that has capacity anyway?

Ofc the other problem with a whole new system is that they can’t install anything smaller than 4.8.

 

[jjrandorin]

I dont think its worth any installers time (including teslas ) to just "install panels onto an existing install". All the paperwork that needs to be done is still there, so even if its technically possible, I havent seen anyone post that any installer does this at all.

 

[h2ofun]

I dont think its worth any installers time (including teslas ) to just "install panels onto an existing install". All the paperwork that needs to be done is still there, so even if its technically possible, I havent seen anyone post that any installer does this at all.

This is why I and many others tells folks to put on as much solar the first time, since for most the cost to add will never happen

 

[jrweiss98020]

A&R Solar in Seattle did my original install and an expansion. Thinking about adding another Powerwall...

 

[lensovet]

This is why I and many others tells folks to put on as much solar the first time, since for most the cost to add will never happen

At the moment we don’t plan on staying in this house for more than 5 years, so over installing didn’t really make sense from a payback period standpoint. What I failed to account for was a change in jobs which added at least 2.5 MWh of consumption annually due to additional car charging. Another life change is now going to add around 2 MWh of car charging usage. Without those two significant users, the originally installed system would have provided excess power annually as it was.

 

[jjrandorin]

A&R Solar in Seattle did my original install and an expansion. Thinking about adding another Powerwall...

In this thread "Expansion" = "Just adding some more panels to an existing inverter". Is that what you are talking about?

Its always possible for a company install a new system (new inverter + new panels) that doesnt touch the original install in any way, and ties into the main panel. Quite a few of our members have 2 systems on their home, and I know of at least a couple that might even have 3 systems on their home. They expanded their systems (by having another inverter, new panels, etc) put on their home.

Thats not what this OP is talking about, though, because they specifically said:

It seems crazy to me that Tesla won’t do this and insists on a completely separate system.

Isn’t it kind of wasteful to install a whole separate system instead of integrating into the existing inverter that has capacity anyway?

Which means they are lamenting the fact that Tesla wont just add some more panels onto their existing install (and perhaps upgrade the inverter).

 

[CrazyRabbit]

You could have a local company install a small enphase system and tie into the existing system/gateway. Or just add 4.8kw tesla system, as long as you have roof space.

 

[lensovet]

Btw the other reason I didn't install more was back when we ordered the system, your options were 4.8 or 9.6 with nothing in between. Now Tesla is letting you do increments of 405 watts (basically individual panels). If that was an option back then, I would have gone with something like 6.5 instead.

I also don't expect to have this commute continue for the next five years, at which point I'd be looking at excessive generation and significantly longer payback periods.

 

[jrweiss98020]

My system uses Enphase microinverters, so adding panels and inverters to the current system was easy. The add-on panels work right along with the original panels.

 

[lensovet]

What are the odds that someone local would be able to tie into the existing system by adding just 6 Tesla panels?

 

[hmcgregoraz]

Hi,

Not via Tesla, but via a local installer, we basically planned to expand the system.

We moved in May of 2019, and when we did the evaluation for solar and power usage, it was summer of 2020, which meant a lot of our driving had gone away during the early parts of Covid...

We sized the system as an 18.5KW DC, 20KW AC (two 10K solar edge inverters), because that was still showing 124% of our yearly usage, and about the most we could get our utility to approve. We justified the 20KW inverter capacity, as 7.6 + 10 would still be less than our panels officially rated output.

In November 2022, we added another ~5KW of DC panels, making the system about 23.5KW DC, 20KW AC, slightly over paneling our inverters. The LG panels we had used were 380W, and LG had moved to 440W, and we swapped a few panels around to make it look cleaner, but overall, the add was relatively painless.

Then in Febuary of 2023, we added 3x PowerWall 2 + Gateway to the system.

Tesla does not like to do anything that requires extra design work. Heck they even refused to bid the solar on our house since it has a "built up" roof, which is at least 25% of the houses in Tucson, and a friend had the same, and they did the install on his house, but now it's not a supported roof type...

-Harry

 

[holeydonut]

Imo the amount of permitting work and headache with warranties and other garbage make a small panel add-on borderline impossible in my experience. The big players have too many installs to take on already, and these small expansions harm their average margins.

Your best bet is to drive around your neighborhood hoping to bump into a crew that is doing a solar install racking/panels. Figure out if you can get a contact information for these folks that seem to be able to lag in mounts/L-feet, know their way with flashing/mastic, cut racking to length, slap in panels, and wire up a new home-run (with ground).

Source a bill of material as if you were going to DIY a solar expansion. But also get a stack of Benjamins in a yellow envelope and label it "not a solar expansion." Include a few 24 packs of beer too.

Something Something Something

Then somehow one day when it's windy a bunch of panels are going to end up on your roof and somehow the wind will also blow your home run to land on some feeder lugs on your inverter or combiner box. Your inverter is still hard-clipped at 3.8 kWp-AC but your production will go up.

Shrug.



PS. I am the dumbest MF-er on this forum, so you may not want to take my advice.

 

[dhrivnak]

We had a 4.8 kW system installed with PW+ (including gateway and integrated inverter) a year ago.

Since then our usage pattern has changed such that it would make a lot more sense to expand the system to have another 2.4 kW installed.

It seems crazy to me that Tesla won’t do this and insists on a completely separate system. I get that they might not want to touch something installed a decade ago by another installer, but this is a project which they designed and installed themselves less than a year ago. Isn’t it kind of wasteful to install a whole separate system instead of integrating into the existing inverter that has capacity anyway?

Ofc the other problem with a whole new system is that they can’t install anything smaller than 4.8.

What inverter do you have? If say you have a 3.8kW or a 3kW inverter then you really cant add more panels and need a new inverter with new panels. But if you have a 5kW inverter then panels can be added. I design solar systems and sometimes it is easy if the capacity is there, but more times than not the spare capacity is not there, unless we know on the front end an expansion is likely.

 

[tfan2018]

Btw the other reason I didn't install more was back when we ordered the system, your options were 4.8 or 9.6 with nothing in between. Now Tesla is letting you do increments of 405 watts (basically individual panels). If that was an option back then, I would have gone with something like 6.5 instead.

I also don't expect to have this commute continue for the next five years, at which point I'd be looking at excessive generation and significantly longer payback periods.

You said you ordered last year. It’s not true you had to choose between 4.8 or 9.6. After the initial design you can email the advisor to change the size and location

 

[lensovet]

You said you ordered last year. It’s not true you had to choose between 4.8 or 9.6. After the initial design you can email the advisor to change the size and location

Lol and how is one supposed to know that exactly? Everything I read on here said Tesla doesn’t do custom stuff. Now the site lets you order arbitrary capacity up front.

 

[Matt-FL]

I can understand that. I found out I could customize my install after several calls into Tesla regarding my order. It wasn't openly apparent, but glad I was able to figure that out. I wanted my PWs in the garage, and upped the kWh on the order. I wish now I had requested a third inverter, but you can't know everything the first time going through it .

 

[tfan2018]

Lol and how is one supposed to know that exactly? Everything I read on here said Tesla doesn’t do custom stuff. Now the site lets you order arbitrary capacity up front.

Hmm everything I learned about tesla solar I pretty much got from this forum. This is where I learned you can customize the size..

 

[holeydonut]

Hmm everything I learned about tesla solar I pretty much got from this forum. This is where I learned you can customize the size..

Lol I feel like if someone uses this forum to learn about Tesla Solar, the last company they would pick to install their solar would be Tesla Solar. At least, if they were browsing the site in 2019/2020 when like every third thread was about how Tesla Solar was screwing the pooch.

 

[lensovet]

What inverter do you have? If say you have a 3.8kW or a 3kW inverter then you really cant add more panels and need a new inverter with new panels. But if you have a 5kW inverter then panels can be added. I design solar systems and sometimes it is easy if the capacity is there, but more times than not the spare capacity is not there, unless we know on the front end an expansion is likely.

I said in my first post this is a PW+ system which comes with an integrated inverter. I’m actually having a hard time finding anything about its max output on either the inverter itself or any of the paperwork Tesla submitted.

The current setup has one red and one black wire going into the high power terminals with corresponding jumpers on the low power side. I would expect to be able to connect at least another independent string if not two.

 

[lensovet]

Then somehow one day when it's windy a bunch of panels are going to end up on your roof and somehow the wind will also blow your home run to land on some feeder lugs on your inverter or combiner box. Your inverter is still hard-clipped at 3.8 kWp-AC but your production will go up

Given my earlier comments about how we don’t plan to stay in this house beyond 5 years this is definitely not going to work