2 vs 3 Powerwalls

[Southpasfan]

Ended up adding the third Powerwall. Thanks for the input, y’all!

You will not only not regret it, you won’t even believe you considered not getting it. Last night my wife and I were chatting with someone and she mentioned giving someone the eGolf, when it gets too old. The first thing that went through my mind was “give it away? It’s got the equivalent of two powerwalls in that frame, I’ll cover it in plants and figure out how to connect it to the system before I give it away!”

 

[holeydonut]

Yeah it's weird how 3 Powerwalls is like 1/3 a Model S in terms of battery capacity. These things are teeny but soooo damn expensive lol.

But for some reason the amount of headache to put the Powerwalls on the wall is like 10,000,000x worse than the effort it takes to park the car in the garage and charge it.

PS, I originally wanted 2 powerwalls, but ended up with 3 due to the large-scale SGIP. And now I wish I had 4. These things are the bomb (literally... since Santa Clara County thinks they're going to thermal runway into oblivion and burn the house down).

 

[Novero]

My 16.3 kw Solar + 2 Powerwall installation is pending and almost done with permitting. With Tesla’s more favorable financing now, I’m considering adding a 3rd Powerwall. I know my home’s AC compressor is compatible with 2 Powerwalls. Is there any clear reason for me to add a 3rd Powerwall to the install? Our daily electricity usage varies between 60-90 kwh this summer depending on our AC use and how much my car needs to charge. We have a gas furnace so electricity usage will be lower in the winter, though we also have an electric dryer.

Also, our utility will be starting some fairly high time-of-use rates, especially between 4-8 pm, some time later this year.

Happy to get any input people can give. Thanks!

Keep in mind that all new powerwalls are the powerwall plus and will be increased by 50% with a firmware update soon

 

[jjrandorin]

Keep in mind that all new powerwalls are the powerwall plus and will be increased by 50% with a firmware update soon

I am not quite sure what you are talking about, but storage is not increased 50%, and "all new powerwalls are powerwall+" is a false statement. Tesla absolutely still sells powerwall 2s.

 

[h2ofun]

I am not quite sure what you are talking about, but storage is not increased 50%, and "all new powerwalls are powerwall+" is a false statement. Tesla absolutely still sells powerwall 2s.

Technically, we have no proof that any PW2 will get new FW to increase anything.

 

[Will792]

I am not quite sure what you are talking about, but storage is not increased 50%, and "all new powerwalls are powerwall+" is a false statement. Tesla absolutely still sells powerwall 2s.

Technically he didn’t write that storage increased 50%. We do know that max current increased 50% in PW2+ and potentially the same change might be applied to the existing PW 2s.

 

[holeydonut]

Technically 3 > 2 so 3 must be better.

 

[h2ofun]

Technically he didn’t write that storage increased 50%. We do know that max current increased 50% in PW2+ and potentially the same change might be applied to the existing PW 2s.

Instant or continuous? If continuous, not sure that would be possible with the existing 10 gauge, 30 amp wiring?

So are PW2+ being wired with 8 gauge, 40 amp breakers to the generation panel?

 

[Vines]

I have seen the post firmware update and it 100% does not increase capacity or continuous output. The firmware upgrade when deployed allows it to start large loads like AC compressors or pumps MUCH better.

Our installs since late last year have all been the newer units, all they are waiting for is that firmware.

I estimate it'll be "2 weeks."

 

[Will792]

Instant or continuous? If continuous, not sure that would be possible with the existing 10 gauge, 30 amp wiring?

So are PW2+ being wired with 8 gauge, 40 amp breakers to the generation panel?

I am almost sure that all Tesla installations use 90C 10AWG wire rated for 40A. If breaker is replaced with 40A everything should be compliant for wiring between generating combiner and PWs. 30A x 1.25 (continuous load factor) = 37.5A, next available breaker size 40A. It does not exceed wire rating in 310.15(B)(16) table.

It is a good point about breakers and possible violations of miscellaneous constraints and limits. I had to get a review of my system with utility company since aggregate wattage of PWs and PV exceeded 20KW. Electric company assumed max feed current of battery systems to be whatever was in the spec then.

The more I think about it the less likely I see a possibility of having this limit raised in the existing units through a firmware update.

 

[Vines]

Sorry but you cannot use the 90C column when determining ampacity at the end of a circuit.

If you are trying to derate a wire for fill factor or temperature, you may start at the rating given by 90C as long as the final number is not larger than the rating at 75C.

The rating at 75C is 35A. The breakers are rated at 75C, so that's as much as you can get out of a #10 copper wire in a normal 240v split phase residential service.

 

[johnterickson]

Yeah it's weird how 3 Powerwalls is like 1/3 a Model S in terms of battery capacity. These things are teeny but soooo damn expensive lol.

But for some reason the amount of headache to put the Powerwalls on the wall is like 10,000,000x worse than the effort it takes to park the car in the garage and charge it.

PS, I originally wanted 2 powerwalls, but ended up with 3 due to the large-scale SGIP. And now I wish I had 4. These things are the bomb (literally... since Santa Clara County thinks they're going to thermal runway into oblivion and burn the house down).

@holeydonut How did you get the large-scale SGIP for the powerwalls? A 3rd-party contractor or maybe you did it yourself?

Looks like Tesla just doesn't want to do the paperwork for large-scale even though there is budget...

Energy Incentives | Powerwall Support

Powerwall is designed to qualify for the Federal Investment Tax Credit (ITC) when it is installed on an existing or new solar system and is charged 100% with solar energy. Discover more about state, utility and local energy incentives here.

www.tesla.com

Tesla will only be submitting customers in the residential budget, therefore only systems of up to 2 Powerwalls will be submitted through Tesla. Other developers may choose to submit applications for systems with 3 or more Powerwalls, but these systems will be subject to additional sizing requirements.

 

[holeydonut]

@holeydonut How did you get the large-scale SGIP for the powerwalls? A 3rd-party contractor or maybe you did it yourself?

Looks like Tesla just doesn't want to do the paperwork for large-scale even though there is budget...

Energy Incentives | Powerwall Support

Powerwall is designed to qualify for the Federal Investment Tax Credit (ITC) when it is installed on an existing or new solar system and is charged 100% with solar energy. Discover more about state, utility and local energy incentives here.

www.tesla.com

The large-scale budget is almost gone... there are still funds listed but it's not 100% there will be any left by the time your application gets out of the planning stage and gets reserved.

But regarding the how; originally I was going to try and get it myself but Sunrun (my installer) actually stepped in and took over the rebate even though they initially did not want to do it.

Of course PG&E tried their best to stymie Sunrun. Sunrun may be the #1 volume leader for total installs and had a ton of installs under the "small scale SGIP". But PG&E forced Sunrun to do a bunch of extra hoops to prove they were legit operation. And PG&E asked 3 different ways for proof that they actually installed a working ESS system in my home. Sunrun's rebate team told me they had never seen PG&E ask that many questions of any of their SGIP customers up until my project.

Anyway, I wouldn't budget a solar+ESS project assuming the large-scale rebate now... it's too risky to plan that way. But your installer can still try to get the funds and maybe it's a nice little bonus/prize if they are successful.

 

[jjrandorin]

@holeydonut How did you get the large-scale SGIP for the powerwalls? A 3rd-party contractor or maybe you did it yourself?

Looks like Tesla just doesn't want to do the paperwork for large-scale even though there is budget...

Energy Incentives | Powerwall Support

Powerwall is designed to qualify for the Federal Investment Tax Credit (ITC) when it is installed on an existing or new solar system and is charged 100% with solar energy. Discover more about state, utility and local energy incentives here.

www.tesla.com

Tesla doesnt do large scale SGIP submissions (unless you are talking about equity and resiliency). You will need to contact a third party installer and see what they say.

 

[ptdusn]

The large-scale budget is almost gone... there are still funds listed but it's not 100% there will be any left by the time your application gets out of the planning stage and gets reserved.

But regarding the how; originally I was going to try and get it myself but Sunrun (my installer) actually stepped in and took over the rebate even though they initially did not want to do it.

Of course PG&E tried their best to stymie Sunrun. Sunrun may be the #1 volume leader for total installs and had a ton of installs under the "small scale SGIP". But PG&E forced Sunrun to do a bunch of extra hoops to prove they were legit operation. And PG&E asked 3 different ways for proof that they actually installed a working ESS system in my home. Sunrun's rebate team told me they had never seen PG&E ask that many questions of any of their SGIP customers up until my project.

Anyway, I wouldn't budget a solar+ESS project assuming the large-scale rebate now... it's too risky to plan that way. But your installer can still try to get the funds and maybe it's a nice little bonus/prize if they are successful.

Hi @holeydonut, I had SunRun do my system here in AZ and I am very happy with their install and support. I got the Hanwa 350w panels with the individual Enphase inverters and 2 PWs. We were activated on Nov 18th and so far I like the performance. We have had 4 days of 100% self-consumption with 5Kw put back to SRP,

 

[holeydonut]

Hi @holeydonut, I had SunRun do my system here in AZ and I am very happy with their install and support. I got the Hanwa 350w panels with the individual Enphase inverters and 2 PWs. We were activated on Nov 18th and so far I like the performance. We have had 4 days of 100% self-consumption with 5Kw put back to SRP,

Yeah my experience with Sunrun wasn’t bad due to their actions, it was all FUBAR because of PG&E and sunrun didn’t know how to handle that stuff. I am however baffled that Sunrun lacks the personnel to deal with PG&E’s BS though.

Sunrun didn’t try to strong arm me into some stupid lease. And their pricing and sales communications were reasonable and informative. The only time they pulled a Tesla and ghosted me was when they had no clue how to address PG&E’s (incorrect) assessment of my underground service.

I’d recommend them for anyone doing a cash buy and not on PG&E’s poop-list.