Should I add a 3rd Powerwall in California?

[RKCRLR]

I'm in a unique situation where I have the opportunity to have a 3rd Powerwall installed on my whole house backup for ~$4400 which would be ~$3300 after ITC.
I'm already a net producer so I only get reimbursed ~$0.03/kWh at True-Up. The ROI for any additional surplus doesn't justify the cost.
I do live in an area of frequent PSPSs and power outages. The extra Powerwall would allow me to run the AC a little further into the evening during a summer outage. The additional Powerwall would have some benefit during a winter outage depending on the weather and the ability of my ~10 KW solar system's ability to recharge it.

My main concern is what is going to happen the future. I'm currently on NEM 2 which is currently set to expire in 2029. However, if NEM 3 goes through the way it was previously proposed it would expire in 2024. Depending on what the CPUC does with NEM 3 and the rates, an additional Powerwall could be a significant advantage.

Looking for opinions and reasons on whether or not I should proceed with getting a 3rd Powerwall installed.

 

[getakey]

for that price, I would

 

[arnolddeleon]

I think you correctly assessed it as not a good simple economic decision with the information we have today. However . . .

If I was in your shoes (frequent PSPS) and I had the ability to swing it (have the money) I would go for it. The reason I would do it is because $3300 is a damn good net price. It will be a long time before technology makes it that the price, in the mean time you get the benefit.

For me going from 2 Powerwalls to 3 was a big change. With 3 I could basically run self powered during most of the year. The freedom to not battery manage so much is amazing. In my case it is not about PSPS or outages (they're too rare, I slightly kid about wishing for more) but instead the closer to worry free about the energy storage side.

 

[SaveOurPlanet]

Where did you find such a good deal? My first impression is BUY IT!. But what is your goal? I would get it if it extends my self reliance on the grid especially you are kind of out there, don't you get outage on fire and snow condition? The ability to charge the PWs from the grid now removes the potential of not being able to fully charge the additional PW. BTW, you have a few wineries up there? Always stop by Placerville for early coffee or late dinner on our way up to Heavenly, but got lost trying to find a winery/dinner place up your way one time and ended up going back down to Placerville and did not get to South Shore till past midnight in a snow storm. Nice country.

 

[BGbreeder]

None of us can predict what the CPUC is going to so, or not do. I see very little in what PG&E is doing that suggests the grid will become substantially more reliable in the future. I think it is a no brainer to put in the extra Powerwall, even if all it does is extend your AC time off grid. The next time you are being smoked out and have a PSPS in your area because of fire, or fire danger, I think you will be a very happy owner.

All the best,

BG

 

[RKCRLR]

Where did you find such a good deal? My first impression is BUY IT!. But what is your goal? I would get it if it extends my self reliance on the grid especially you are kind of out there, don't you get outage on fire and snow condition? The ability to charge the PWs from the grid now removes the potential of not being able to fully charge the additional PW. BTW, you have a few wineries up there? Always stop by Placerville for early coffee or late dinner on our way up to Heavenly, but got lost trying to find a winery/dinner place up your way one time and ended up going back down to Placerville and did not get to South Shore till past midnight in a snow storm. Nice country.

It's a long story but the short of it is my system was supposed to be a whole home backup but the SureStart start device Tesla installed wasn't compatible with my heat pump compressor and, as such, didn't operate properly. Tesla offered me a 3rd Powerwall at the discounted price to supply enough current for the start surge. In the mean time my compressor failed (quite possibly due to the SureStart being installed) so I'm replacing my condensing unit with an inverter type that doesn't require a high starting current.

Having the 3rd Powerwall would be a little help a little during outages but not substantially. I rarely need to rum my AC deep into the night in the summer and the solar output is the limiting factor in the winter. Storm Watch has been pretty good at charging the Powerwalls before predicted storms, I don't know if I could do much better in the winter. And if the power is out for days in the winter I need to run my generator anyway.

Yes, there is a lot of small family owned wineries around me, sort of like Napa was decades ago. My cousin has a winery in Somerset (Cantiga) and makes wines the Old World style with no added nitrates.

 

[SaveOurPlanet]

There is no tangible ROI for PW and personally I would rather have it and not need it than need it and not have it, also I feel good about providing 100% of my own energy though sadly only 7 months out of the year. If the cost does not impact you much financially then just get it (it's like breaking 2 bottles of Screaming Eagle, just kidding) the additional PW also may enhance your overall storage over time due to degradation of the other 2 PWs.

 

[getakey]

there's no tangible ROI for a generator either. At least the PW provides some benefit every day

 

[jjrandorin]

At that price I would, especially if thats "installed and setup with my current system" at that price. No ROI on it, but given that I think the others for you were equity and resiliency SGIP subsidized, it sounds like an effort for tesla to "make it right" and I think I would go for it even if the ROI isnt really there.

More independence than ROI, but for me that would mean something.

 

[SaveOurPlanet]

there's no tangible ROI for a generator either. At least the PW provides some benefit every day

You are absolutely right and our planet will be thankful for not firing up that generator.

 

[arnolddeleon]

It's a long story but the short of it is my system was supposed to be a whole home backup but the SureStart start device Tesla installed wasn't compatible with my heat pump compressor and, as such, didn't operate properly. Tesla offered me a 3rd Powerwall at the discounted price to supply enough current for the start surge. In the mean time my compressor failed (quite possibly due to the SureStart being installed) so I'm replacing my condensing unit with an inverter type that doesn't require a high starting current.

Variable speed inverter based compressors are awesome! You will enjoy it.

 

[sunwarriors]

Too cheap to not want to buy it as well IMO.

Our power is very stable here and it's impossible for me to make any ROI case for batteries honestly, but like some of you folks when you first got PWs, I'm still waiting for a rolling blackout to smile that I have power (and to test it of course).

(I hear TX is hitting 100+ in some areas now). I hear this summer is going to be super hot and bad.

 

[aesculus]

Variable speed inverter based compressors are awesome! You will enjoy it.

I agree. They are also much quieter, which means a lot to me since the compressors are right outside my bedroom window.

Not sure why they call them inverter though. That makes no sense to me. Variable speed I get.

 

[Vines]

I agree. They are also much quieter, which means a lot to me since the compressors are right outside my bedroom window.

Not sure why they call them inverter though. That makes no sense to me. Variable speed I get.

They invert AC to DC which can be controlled efficiently to drive the compressor with less losses.

 

[aesculus]

They invert AC to DC which can be controlled efficiently to drive the compressor with less losses.

Don't tell Tesla that who firmly believes in AC motors.

And now how to I get my HP's to do regen heating?

 

[Vines]

Don't tell Tesla that who firmly believes in AC motors.

And now how to I get my HP's to do regen heating?

I believe the difference is that when you start with 60 hz AC power, it makes more sense to invert to DC. I don't fully understand however, and was also confused when I saw my 3 had a 3 phase AC synchronous motor

 

[RKCRLR]

They invert AC to DC which can be controlled efficiently to drive the compressor with less losses.

I think it mainly has to do with wanting to operate the compressor at variable speeds. AC motors like to operate at a single speed. DC motors can efficiently operate at variable speeds. I have a zoned system so when only heating or cooling one zone the compressor will operate at a lower speed. Interestingly, the outside unit I'm getting isn't continuously variable but has 5 set inverter outputs for 5 set stages, the lowest stage is 20% of high stage.

 

[wwhitney]

They invert AC to DC which can be controlled efficiently to drive the compressor with less losses.

I think you mean invert DC to AC. Making DC from AC is calling rectifying.

I don't think those generators do AC -> DC -> AC do they? I assume they generate DC.

Cheers, Wayne

 

[RKCRLR]

I think you mean invert DC to AC. Making DC from AC is calling rectifying.

I don't think those generators do AC -> DC -> AC do they? I assume they generate DC.

Cheers, Wayne

I was thinking inverter compressors ran off DC motors but I guess they operate by shifting the voltage and frequency on an AC motor, so I guess the term "inverter" is correct for those systems.

 

[RKCRLR]

Variable speed inverter based compressors are awesome! You will enjoy it.

My biggest fear is if the control board goes out since they are expensive. When I asked my dealer how much they cost he said he didn't know. If it failed within warranty they send him a replacement board. If it fails out of warranty he just replaces the whole unit.