Tesla App Utility plan configuration: Multiple Peaks, Buy/Sell Behavior, etc

[JakiChan]

There is no thread on powerwall longevity, and there is no way to manage "not charging to 100%" like the you can in the vehicles. You can set your reserve to reduce depth of discharge, but your choice is to either not discharge at all, or go from X % to 100 unless your solar wont fill up the batteries.

Wasn't planning on "not charging to 100%". It was more "maybe I don't need to always be on self powered". I would like to do TBC - I guess if I entered a fake rate plan it would let me.

There are other applications where Tesla warranties the Powerwalls for 37.8 MWh aggregate throughput (2800 cycles) so that gives you an idea of the design life.

As others have said, that's when it has 70% total storage left, correct? So 9.45kWh per Powerwall?

My personal goal is to have the Powerwalls last 20 years. If the 37.8 MWh is the actual design life then that means I should limit the annual throughput to 1.89 MWh/140 cycles per Powerwall, or an average discharge of 38%.

Not sure how that math works out since it doesn't really include the degradation curve.

Tesla says its the 70% design life, not the product design life.... but we have had this discussion before.

What is the difference (according to Tesla)? Feel free to link to prior threads or suggest search terms.

 

[RKCRLR]

As others have said, that's when it has 70% total storage left, correct? So 9.45kWh per Powerwall?

Not sure how that math works out since it doesn't really include the degradation curve.

My interpretation is that the 37.8 MWh aggregate throughput relates to the point that the Powerwall would fall below 70% of its original 13.5 kWh storage capacity. So, yes, a 9.45 kWh Powerwall.

The math is just a crude estimate of expected Powerwall life. Powerwalls could start dying soon after warranty regardless of throughput or they could last for decades if lightly used, we don't know at this point. If there is better data out there it would be interesting to see.

 

[JakiChan]

My interpretation is that the 37.8 MWh aggregate throughput relates to the point that the Powerwall would fall below 70% of its original 13.5 kWh storage capacity. So, yes, a 9.45 kWh Powerwall.

The math is just a crude estimate of expected Powerwall life. Powerwalls could start dying soon after warranty regardless of throughput or they could last for decades if lightly used, we don't know at this point. If there is better data out there it would be interesting to see.

I'm just trying to find a balance between "use em hard" and "don't use them at all".

I also hope we can find smart home integration options in the future. Maybe someone will write it. If I have a smart thermostat (which I do) I'd love logic like "precool home while there's excess solar and once solar falls off and powerwalls kick in raise the temperature a few degrees". I can estimate that with a schedule, but that kind of integration would be fun.

 

[cwied]

I pay ~$0.03/kWh in Non-Bypasable Charges for the energy I draw from the grid. How do I explain this to the Tesla app? Do I add $0.03/kWh to the sell prices, subtract $0.03/kWh from the buy prices, or make all the buy prices $0 and all the sell prices $0.03/kWh since I'm a net producer? And how should I expect the app behavior to change over leaving the buy/sell prices as they are?

Subtracting $.03 from the sell price should work. When you do this, the Powerwall algorithm should prefer using solar to feed house load to exporting. This means that it will switch to using only excess solar to charge if it thinks it will reach 100% before the off-peak period ends, for example (as opposed to filling up on all solar and then exporting for the rest of the period).

 

[RKCRLR]

Subtracting $.03 from the sell price should work. When you do this, the Powerwall algorithm should prefer using solar to feed house load to exporting. This means that it will switch to using only excess solar to charge if it thinks it will reach 100% before the off-peak period ends, for example (as opposed to filling up on all solar and then exporting for the rest of the period).

Thanks, this is working out pretty good. There some nuances but I'm going to keep it at these settings for awhile to see how it does. I definitely like that it now diverts morning solar to both recharging the Powerwalls and running the home.

 

[Mark Purcell]

I also hope we can find smart home integration options in the future. Maybe someone will write it. If I have a smart thermostat (which I do) I'd love logic like "precool home while there's excess solar and once solar falls off and powerwalls kick in raise the temperature a few degrees". I can estimate that with a schedule, but that kind of integration would be fun.

Come on over to Home Assistant. That is exactly what we are doing today.

Intro / Quick start — emhass 0.8.5 documentation

 

[JakiChan]

Come on over to Home Assistant. That is exactly what we are doing today.

Intro / Quick start — emhass 0.8.5 documentation

Does HomeAssistant support HomeKit? I went with HomeBridge to give me Siri control over things.

 

[PowerMonster]

Trying to get my Powerwalls to discharge only during my Peak hours on TOU plan. When I select Time-Based control on app I still pull from grid only during the peak time. Batteries remain in standby mode. Switch to self powered and they start discharging immediately and supple the power for the house. Am I doing something wrong? My Rate plan is selected in the App and it shows my correct TOU hours so not sure why it's not working.

 

[miimura]

Trying to get my Powerwalls to discharge only during my Peak hours on TOU plan. When I select Time-Based control on app I still pull from grid only during the peak time. Batteries remain in standby mode. Switch to self powered and they start discharging immediately and supple the power for the house. Am I doing something wrong? My Rate plan is selected in the App and it shows my correct TOU hours so not sure why it's not working.

Try turning TBC on a couple hours before the start of the Peak period. There used to be a granularity to when it would take changes. I am not sure if that still applies.

 

[Redhill_qik]

Trying to get my Powerwalls to discharge only during my Peak hours on TOU plan. When I select Time-Based control on app I still pull from grid only during the peak time. Batteries remain in standby mode. Switch to self powered and they start discharging immediately and supple the power for the house. Am I doing something wrong? My Rate plan is selected in the App and it shows my correct TOU hours so not sure why it's not working.

What the rates for your Peak and Off-Peak rates. If the difference is less than 10% then there is no benefit of discharging during peak as the benefit will be lost due to the 90% efficiency for recharging, so the control algorithm doesn't disharge.

 

[PowerMonster]

Sorry, just saw your reply. My off peak is $0.47 and peak is $0.55 so only 8 cents difference. If this is the issue, what would you recommend for settings? I have been manually switching between the 4-9pm peak but kind of a pain LOL.

 

[Redhill_qik]

Sorry, just saw your reply. My off peak is $0.47 and peak is $0.55 so only 8 cents difference. If this is the issue, what would you recommend for settings? I have been manually switching between the 4-9pm peak but kind of a pain LOL.

That is more than a 10% difference so it should be exporting as it is ever so slightly more cost advantaged. I would trying editing the rate plan and dropping the off-peak down to $0.40.

 

[PowerMonster]

Thank you I will try adjusting the rate down and see how that works.

 

[PowerMonster]

And just like that, magically came on at Peak time LOL. Thank you for your help.

 

[Mark Purcell]

Does HomeAssistant support HomeKit? I went with HomeBridge to give me Siri control over things.

Yes, I have a few HomeKit devices in Home Assistant, the integration is quite tight.

HomeKit Device

Instructions for how to integrate your HomeKit devices within Home Assistant.

www.home-assistant.io

 

[nfarina]

We just had 2 Powerwalls installed for whole-home backup (yay!), adding to our existing (7+ years) 3rd party solar system.

We're with Pacific Power in Oregon, and we've had a NEM plan that "banks" credits for us. So if we send 1kW to the grid, we get 1kW credit when we need it later. We always use all our credits since our system is small (5kW).

How do I reflect these credits in our custom Utility Rate Plan? We're on a TOU plan so energy costs more on-peak, but we don't "sell" energy for more during on-peak.

What I want is to never pay on-peak prices of course. So I'd expect Powerwall to only discharge during peak times. Originally, I set the "sell" price to zero across the board, but over the weekend I noticed the Powerwall discharged continually at all times, on-peak and off-peak. Not what I want!

Should I configure the "sell" price to be the lower of the two instead? (image attached) What's the "right" way to reflect NEM with credits?

 

[BGbreeder]

You probably want to try a price difference during peak that is more than 10%, so the Tesla algorithm will do self powered rather than export.

 

[nfarina]

You probably want to try a price difference during peak that is more than 10%, so the Tesla algorithm will do self powered rather than export.

Thanks! I will try that next, going to see if the current plan of setting identical "sell rates" of $0.09 will do what I want.

I was mostly curious to know if anyone knew the "official" way to represent "sell prices" for energy when it's just kW credits.

 

[Redhill_qik]

Thanks! I will try that next, going to see if the current plan of setting identical "sell rates" of $0.09 will do what I want.

I was mostly curious to know if anyone knew the "official" way to represent "sell prices" for energy when it's just kW credits.

Are you sure that you understand the solar plan for credits? It seems strange that you have both TOU rates with Peak/Off-Peak price differences, but you can also send kWh to the grid and get back an equal number of kWh? Is it TOU-to-TOU (Peak-to-Peak and OffPeak-to-OffPeak) or if you send in Off-Peak you can import during Peak?

 

[cwied]

Are you sure that you understand the solar plan for credits? It seems strange that you have both TOU rates with Peak/Off-Peak price differences, but you can also send kWh to the grid and get back an equal number of kWh? Is it TOU-to-TOU (Peak-to-Peak and OffPeak-to-OffPeak) or if you send in Off-Peak you can import during Peak?

Here's a solar tariff document that I found for Pacific Power: https://www.pacificpower.net/conten...Service_Optional_for_Qualifying_Customers.pdf
In particular, under "Special Conditions" here is a paragraph on TOU:

3. For customers who are billed on time-of-use rates, kilowatt-hour usage during a monthly billing period shall be offset in the following sequence: (i) first by kilowatt-hours generated during the same time-of-use period; (ii) second by kilowatt-hour credits from previous monthly billing periods, but from the same time-of-use period; (iii) third by kilowatt-hours generated during different time-of-use periods, but from the same monthly billing period; (iv) last by kilowatt-hour credits from previous monthly billing periods and from different time-of-use periods.

This does make it sound like off-peak generation can potentially be used to offset peak usage, but only if all the off-peak usage has already been offset.