Tesla Powerwall with 2.45 kW

[lucacome]

Hi, I’m in the process of buying a new apartment in CA and it comes with the option for solar, everything in the apartment is fully electric (there’s not even gas in the building). They only offer 2.45 kW and according to their estimate it should cover ~50% of the needs for the 1300+ sq ft apartment.
Do you think it still makes sense to add a Powerwall or the system is too small?

 

[ptdusn]

Definitely would add the Powerwall. Then you would be able to run the Apt. off the Powerwall at night. Additionally, if the grid goes down, you will have power. I would see if they could bump the PVs to a 5- or 6-Kw system.

 

[jjrandorin]

Do you even have an private space to install one, if you wanted to?

I dont think I would buy a powerwall under the circumstances of "solar only provides 50% of expected usage". You wont really have any power to fill it with, and my experience with "expected usage" is that "its an average" so you wont know what YOUR usage is until you live there, with your stuff.

 

[SVDNN]

Would agree with above...assume you know backup limits with solar only (cannot use solar power if grid out and sunny outside without Powerwalls). And then power use shift off of peak rates with use of Powerwalls.
ROI is variable based on your value of a backup...hard to get ROI only with rate shift considerations but depends on your use.
Only other issue for you specifically...you will have to see what the HOA for condo/apt complex will allow for battery storage system.

 

[miimura]

I have two Powerwalls with 4.32kW of solar. One Powerwall with 2.45kW of solar doesn't seem that bad to me. The question is whether your rates and use case would really benefit from the Powerwall.

I got Powerwalls because I'm in a suburban area that has lots of trees and overhead power lines. We used to average an outage a month and usually accumulated about 8-10 hours of outage a year. However, PG&E has been more serious about tree trimming and the number of outages in 2021 was dramatically lower than 2019 and prior. I also have PG&E EV2 rates that have punitive Summer Peak rates. The Powerwalls allow me to completely avoid paying that rate. It saves me about $700/year.

 

[jrweiss98020]

I dont think I would buy a powerwall under the circumstances of "solar only provides 50% of expected usage". You wont really have any power to fill it with, and my experience with "expected usage" is that "its an average" so you wont know what YOUR usage is until you live there, with your stuff.

I disagree. Set the Powerwall for "Backup Only". It will charge during periods of low demand during the day, then remain charged until a grid outage. I can get my house load down to less than 400 Watts without trying too hard...

I agree that 2.45 kW is too small for dependable, practical use. If possible, size it for as close to 100% of demand as feasible.

 

[jjrandorin]

I disagree. Set the Powerwall for "Backup Only". It will charge during periods of low demand during the day, then remain charged until a grid outage. I can get my house load down to less than 400 Watts without trying too hard...

I agree that 2.45 kW is too small for dependable, practical use. If possible, size it for as close to 100% of demand as feasible.

Sure, you could do that (use it in backup only mode). I just wouldnt, for a condo (what I would call a purchasable apartment), as there are cheaper ways to get temporary power, and its a shared building anyway so the challenges of getting it installed are greater.

I was answering the question of "does it make sense", with my opinion of "no it doesnt", at least to me. Those ecoflow units in the thread recently discussing them make a lot more sense to me, in this application:

Ecoflow Discussion

First...it doesn't seem like there's an Ecoflow type thread here, but LMK if there is and I'm just an idiot and can't figure out basic search parameters. Anyway, I took delivery of two EcoFlow ∆ Pro units last month. I was smart enough to buy them right when they went live so I missed the...

teslamotorsclub.com

 

[RichardCullip]

How are you going to charge that Powerwall? I doubt you could economically justify the cost of a Powerwall with that small of system, especially if you "expect" only covering 50% of your electrical use. That being said, there might be other reasons to have a Powerwall as a backup for anticipated power outages. What is that worth to you?

 

[jboy210]

Is there any option to post-sales add more solar?

 

[lucacome]

Do you even have an private space to install one, if you wanted to?

I dont think I would buy a powerwall under the circumstances of "solar only provides 50% of expected usage". You wont really have any power to fill it with, and my experience with "expected usage" is that "its an average" so you wont know what YOUR usage is until you live there, with your stuff.

...
Only other issue for you specifically...you will have to see what the HOA for condo/apt complex will allow for battery storage system.

Yeah I have a private garage and I was planning on installing it there. Not sure about how to estimate my consumption since I don't live there yet, but I would assume it's really energy efficient since everything is brand new being built right now. I'm also going to be working from home for the foreseeable future and I'm not sure that was factored in their estimate.

I disagree. Set the Powerwall for "Backup Only". It will charge during periods of low demand during the day, then remain charged until a grid outage. I can get my house load down to less than 400 Watts without trying too hard...

I agree that 2.45 kW is too small for dependable, practical use. If possible, size it for as close to 100% of demand as feasible.

Is there any option to post-sales add more solar?

I asked for a bigger system but unfortunately there's limited space on the roof and each condo has a limited number. My hope is that somebody didn't want solar and I can take their space, but I have no idea if that's even a possibility.

Sure, you could do that (use it in backup only mode). I just wouldnt, for a condo (what I would call a purchasable apartment), as there are cheaper ways to get temporary power, and its a shared building anyway so the challenges of getting it installed are greater.

I was answering the question of "does it make sense", with my opinion of "no it doesnt", at least to me. Those ecoflow units in the thread recently discussing them make a lot more sense to me, in this application:

Ecoflow Discussion

First...it doesn't seem like there's an Ecoflow type thread here, but LMK if there is and I'm just an idiot and can't figure out basic search parameters. Anyway, I took delivery of two EcoFlow ∆ Pro units last month. I was smart enough to buy them right when they went live so I missed the...

teslamotorsclub.com

Never heard about ecoflow before, looking into it...

How are you going to charge that Powerwall? I doubt you could economically justify the cost of a Powerwall with that small of system, especially if you "expect" only covering 50% of your electrical use. That being said, there might be other reasons to have a Powerwall as a backup for anticipated power outages. What is that worth to you?

I've only experienced one 15 min blackout since I moved to the Bay Area 6 years ago so I'm not too concerned about outages I think...


So it seems like the system wouldn't be enough to charge the powerwall during off-peak and use that power during peak hours

 

[jjrandorin]

Yeah I have a private garage and I was planning on installing it there. Not sure about how to estimate my consumption since I don't live there yet, but I would assume it's really energy efficient since everything is brand new being built right now. I'm also going to be working from home for the foreseeable future and I'm not sure that was factored in their estimate.






I asked for a bigger system but unfortunately there's limited space on the roof and each condo has a limited number. My hope is that somebody didn't want solar and I can take their space, but I have no idea if that's even a possibility.


Never heard about ecoflow before, looking into it...



I've only experienced one 15 min blackout since I moved to the Bay Area 6 years ago so I'm not too concerned about outages I think...


So it seems like the system wouldn't be enough to charge the powerwall during off-peak and use that power during peak hours

if it is only projected at 50% of your usage, as I mentioned, thats an average estimate and likely not counting "working from home for the foreseeable future". Given that amount of PV (solar) that will cover, at best, 50% of your usage, is it going to cover your home usage during daylight, and have enough to fill a powerwall, daily? I dont know, but I dont think so.

 

[ThomasD]

How strict is your HOA and do you need their approval to do anything to your space

 

[lucacome]

How strict is your HOA and do you need their approval to do anything to your space

I haven’t read all the HOA documents yet but I think I can add the powerwall inside my garage, if that's why you're asking

if it is only projected at 50% of your usage, as I mentioned, thats an average estimate and likely not counting "working from home for the foreseeable future". Given that amount of PV (solar) that will cover, at best, 50% of your usage, is it going to cover your home usage during daylight, and have enough to fill a powerwall, daily? I dont know, but I dont think so.

I guess I would have to see once I move in how much energy I use. It sucks that I can't charge it off-peak and use it on peak hours...

 

[jjrandorin]

I haven’t read all the HOA documents yet but I think I can add the powerwall inside my garage, if that's why you're asking




I guess I would have to see once I move in how much energy I use. It sucks that I can't charge it off-peak and use it on peak hours...

If thats a requirement, you could have it setup that way if you dont get solar at all. A powerwall can charge from the grid in off peak and discharge during peak in the US if there is no solar present at all (ignoring the fact that one can change settings using the installer interface to charge from the grid which is not something we discuss here).

 

[yblaser]

It sounds like the builder is installing the solar as part of the build. Do they have the option of adding a Powerwall or would that be a completely separate install by someone else? If so that certainly will add complications and expense to adding a Powerwall after the fact.

 

[lucacome]

Yeah the builder is installing as part of the build and they picked the company (and I don't have a say in it) SunPower. They also have a battery system and just confirmed that they wouldn't be able to add it because they require at least 4 kW.

On their website they mention that it's compatible with the powerwall, but when I asked the representative they said it's not possible to do add it right now and that I would have to do it later on and confirm with Tesla.