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Time of Use Power Shifting for Powerwall 2

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I've been hearing conflicting pieces of information. I have Quantity 2 Powerwall getting installed on Wednesday next week. I live in a townhouse complex, so no Solar right now (maybe in the future). I wanted the Powerwall 2 because I currently am on EV-A because of my Model S.

What I want to do is to charge the two Powerwall 2 between 11pm and 6am @ $0.125 and use it throughout the day. My average daily usage is around 14kw, so that's why I went with two Powerwall.

I'm hearing that even with the latest firmware for the Powerwall, that Tesla does not yet support Time of Use Power Shifting, and right now all your an do is do whole home backup.

Is this true? All of the online documentation and the events they held at the factory in Fremont, indicated that we could do Time of Use Power Shifting.

I've tried searching in this group, but I'm seeing old posting that say the same thing, that it is supported by the hardware, but I can't find anyone WITHOUT solar who is doing this.

Can any exiting Powerwall user confirm this?

Note: When I run through my calculations based on PG&E web site for daily usage, I'm saving over 50% of my bill because during daytime hours we're paying upwards of $0.40/kwh, and with the Time of Use Power Shifting, I'll be consume stored energy at $0.125/kwh.

Note: We have AC, but we barely used it. The few days we do use it, we use around 20kwh per day, so two Powerwall will handle that.

Note: All the numbers above exclude the Model S because my Powerwall will be off grid, and NOT connected to the power walls (or that's my plan)


I have the same issues, so before buying, I asked this question and got this answer from an Energy Advisor at Tesla HQ:

Q: We are on TOU with SCE, so the challenge for which I would like to consider PowerWall is to bridge the costly evening hours from sundown to 10:00 PM, at which time my cost per kWh drops from $0.46 yo $0.11. Does the PowerWall software allow this to happen automatically?

A: Absolutely. You’ll be able to pre-program the powerwall at your own discretion. You can also go into your Powerwall app manually at any time to adjust and/or edit.
 
Isn't that going to cause a problem with the warranty? I thought when not being used for backup, the unlimited cycles part of the warranty doesn't apply, and you are limited to 37.8 MWh of charge/discharge?

What document did you see that piece of information in? Tesla does specify that the Powerwall can be used for both Whole Home Backup and Time of Use Load Shifting as per the FAQ (URL below) and there's no mention in any of the documentation I received with my Powerwall 2 last week that limits the number of charge/discharge (unless I missed something while reviewing each of them)

I'm guessing in my case, 2 Powerwall will deliver 27kwh. I use on average 15kwh, and when the Time of Use Load Shifting firmware comes out by end of year (not currently with v1.5.1), I'll set it to automatically charge every night starting at 11pm and Self Power the house starting at 6am until 11pm again. In this case, it will be charging every single day (a few days of the year when we go on vacation, our daily usage goes down considerably, but let's exclude that for discussion purposes).

365 discharge/charge, and let's assume that I'll be charging 14kwh each time, so that's 5.1mwh per year, and we have a 10 year warranty, so that means 51mwh over it's warranty lifetime.

Is my math correct with the assumption of charging 14kwh every day of the year?

URL = Powerwall FAQs

"...
What can I use Powerwall for?
Powerwall can be used for a variety of applications, including:


  • Self-Powering your Home
    With Powerwall you can use more of your solar by storing the excess energy and using it at night, which roughly doubles the amount of solar energy that directly powers your home.
  • Backup Power
    Powerwall provides seamless backup power in the event of a utility power outage. For a longer outage, Powerwall can recharge from your solar power system. If necessary, you can even run your home off solar and Powerwall indefinitely.
  • Home Energy Monitoring
    You can monitor your solar, Powerwall and home energy use in real time with the Tesla mobile app.
  • Time-of-Use Load Shifting
    If your utility offers a time-of-use rate plan, Powerwall can charge when rates are low and use that energy during expensive times to reduce your electricity bill. This feature will be available at a later date by an over-the-air update.
..."
 
I also noticed this in the same FAQ that I referenced above.

Note: I think Time of Use Load Shifting is considered part of Self Powered mode, which is the same... storing energy and using it later.

"...
What is Powerwall’s warranty and maintenance requirements?
Powerwall does not require maintenance and comes with a 10-year unlimited cycle warranty when used in Self-Powered or Backup mode.
..."
 
...

A: Absolutely. You’ll be able to pre-program the powerwall at your own discretion. You can also go into your Powerwall app manually at any time to adjust and/or edit.

I don't see any way to adjust and/or edit anything in the Powerwall app. All I can do is view "power flow", and "backup History" (17 in the past 24 hours!?!) Tesla Motors app? Or is there a separate Powerwall app? Web page?
 
I don't see any way to adjust and/or edit anything in the Powerwall app. All I can do is view "power flow", and "backup History" (17 in the past 24 hours!?!) Tesla Motors app? Or is there a separate Powerwall app? Web page?
If your running in Whole Home Backup what you see is it.

Later on in the year when they release the Time of Use Load Shifting then you will have some configurable options.

In Whole Home a Backup they set the charge rate to 100% and that’s its. There is nothing else to configure.
 
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What document did you see that piece of information in? Tesla does specify that the Powerwall can be used for both Whole Home Backup and Time of Use Load Shifting as per the FAQ (URL below) and there's no mention in any of the documentation I received with my Powerwall 2 last week that limits the number of charge/discharge (unless I missed something while reviewing each of them)

I'm guessing in my case, 2 Powerwall will deliver 27kwh. I use on average 15kwh, and when the Time of Use Load Shifting firmware comes out by end of year (not currently with v1.5.1), I'll set it to automatically charge every night starting at 11pm and Self Power the house starting at 6am until 11pm again. In this case, it will be charging every single day (a few days of the year when we go on vacation, our daily usage goes down considerably, but let's exclude that for discussion purposes).

365 discharge/charge, and let's assume that I'll be charging 14kwh each time, so that's 5.1mwh per year, and we have a 10 year warranty, so that means 51mwh over it's warranty lifetime.

Is my math correct with the assumption of charging 14kwh every day of the year?

URL = Powerwall FAQs

"...
What can I use Powerwall for?
Powerwall can be used for a variety of applications, including:

  • Self-Powering your Home
    With Powerwall you can use more of your solar by storing the excess energy and using it at night, which roughly doubles the amount of solar energy that directly powers your home.
  • Backup Power
    Powerwall provides seamless backup power in the event of a utility power outage. For a longer outage, Powerwall can recharge from your solar power system. If necessary, you can even run your home off solar and Powerwall indefinitely.
  • Home Energy Monitoring
    You can monitor your solar, Powerwall and home energy use in real time with the Tesla mobile app.
  • Time-of-Use Load Shifting
    If your utility offers a time-of-use rate plan, Powerwall can charge when rates are low and use that energy during expensive times to reduce your electricity bill. This feature will be available at a later date by an over-the-air update.
..."


Well, when I googled for the Tesla Powerall 2 warranty, I got this: https://www.tesla.com/sites/default/files/pdfs/powerwall/powerwall_2_ac_warranty_us_1-4.pdf

It's listed as being effective as of April this year, and I didn't see another one. It clearly states the 37.8 MWh limitation for any application other than "Solar self-consumption/backup only".

Is there a more up to date version that I am missing? Of course you can use it for TOU shifting etc..., its just the warranty has the 37.7 MWh limit. I did a similar calc and it would use more than this limit, so I am not sure where that number came from.

thx
mike
 
Well, when I googled for the Tesla Powerall 2 warranty, I got this: https://www.tesla.com/sites/default/files/pdfs/powerwall/powerwall_2_ac_warranty_us_1-4.pdf

It's listed as being effective as of April this year, and I didn't see another one. It clearly states the 37.8 MWh limitation for any application other than "Solar self-consumption/backup only".

Is there a more up to date version that I am missing? Of course you can use it for TOU shifting etc..., its just the warranty has the 37.7 MWh limit. I did a similar calc and it would use more than this limit, so I am not sure where that number came from.

thx
mike

That may be correct for now until Time of Use Load Shifting Arrives.

365 discharge/charge, and let's assume that I'll be charging 14kwh each time, so that's 5.1mwh per year, and we have a 10 year warranty, so that means 51mwh over it's warranty lifetime.
 
365 discharge/charge, and let's assume that I'll be charging 14kwh each time, so that's 5.1mwh per year, and we have a 10 year warranty, so that means 51mwh over it's warranty lifetime.
It's unlikely that you'd want to fully cycle the PW2 every day, as it's typically a good idea to maintain a backup reserve. Also, the usable capacity is more like 13.1 kWh based on California SGIP guidelines. Therefore, I think it's highly unlikely that normal users would come close to exceeding the 37.8 MWh warranty ceiling within ten years.
 
It's unlikely that you'd want to fully cycle the PW2 every day, as it's typically a good idea to maintain a backup reserve. Also, the usable capacity is more like 13.1 kWh based on California SGIP guidelines. Therefore, I think it's highly unlikely that normal users would come close to exceeding the 37.8 MWh warranty ceiling within ten years.
Very true.

Right now I'm doing manual "Time of Use Load Shifting" and I try to keep it at 30% minimum.
 
I did a calculation as follows: Download smart meter data as a spreadsheet for 12 months, filtered 7AM-2PM, filtered for only negative energy use (generation), highlighted the hourly generation, and see 4.2 MWh / year of "partial peak" generation. This 37.8 MWh divided by 4.2 MWh, yr equals 9 years before the stated warranty ceiling. The assumption is I only charge with solar and only self-consume solar excess.

Is it me or do I see a mismatch? Supposedly "self consumption" is unlimited warranty.

Initially this struck a bad chord until I realized I am planning to have two Powerwalls installed. I find this to be a new discovery and a good reason to install two packs. Even if the 9 years now is 18 years, it doesn't explain how the warranty can be unlimited.
 
I flip my main breaker at 11pm to ON which means the Powerwall starts to charge. At 6am I flip it OFF so my entire house runs off the battery.

I’m in the EVA plan so when I do this all my electricity is at the discounted $0.125/kW cost. At peak it is $0.41/kW.
I assume that you don’t have solar then. Othereise you would not be able to feed your excess solar to the grid