# Question about configuring the Powerwall Advanced settings



## 2Intense (May 3, 2021)

I have a solar system as well as 4 Tesla Powerwalls and I am trying to come to terms with how I should be using Tesla's advanced mode option given my circumstances. 
First let me explain. I am on a TOU (Time of Use) rate plan with the power company. I pay a peak rate of $.45 per KWh from 4PM-9PM and a standard rate of $.17 per KWh the rest of the time. The NESCR (Net Energy Surplus Compensation Rate), or rate that I get reimbursed for the excess energy I produce and send back to the grid about $.03 per KWh. (varies between $.02-$.03 depending upon month). 

If I run in advanced mode and have it set for the house to shift to battery power between 4PM-9PM I am consuming power I produced from solar and avoiding the $.45 per KWH period. At 9PM the batteries cease providing power and the house switches back to the grid and when the sun comes up, excess power that my solar produces will flow to top off the batteries before going to the grid. Then once the batteries are full, the overage goes back to the grid. My solar produces @ 85KWh of energy per day and consume @65 KWh per day. It's notable that about 50% of my consumption occurs during the peak period of 4PM-9PM.

So, basically I avoid paying the $.45 per KWH for 5 hours a day and of course lose the $.03 per KWH for the energy going into recharging my Powerwalls. (I know there's another 10% loss due to the AC/DC conversion process but again that would be computed at the $.03 rate). This seems like the best way to go, right? 

Or,

Should I have it set to run all night? Come on at 4PM to avoid Peak rates and continue to run until 4, 5, 6, or 7AM and use all of my daily excess KWh and a large portion of my Solar to recharge the batteries during the day at the $.17 rate?

Setting aside the cycles on the batteries, how should I be doing this to optimize cost savings?


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## Ed Woodrick (May 26, 2018)

What is your intent? Are you solely trying to reduce the cost of electricity? Are you trying to provide power back in case of power failure? Or something else?

You need to watch and see how much power you use during the 4-9PM period. Is it more than the batteries can provide?

You really need to look at the amount of power that you use per hour on average and possible per season. Your power company may have the information for you.

I believe that the general thoughts are to kick on the batteries at 4 and run until you get down to a reserve percentage. The reserve is in the case of a power failure.
Determine the amount of solar that you can produce and then determine how long it will take to recharge the batteries. Make sure that the batteries can be fully charged, even on cloudy days, by 4PM.


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## 2Intense (May 3, 2021)

Ed Woodrick said:


> What is your intent? Are you solely trying to reduce the cost of electricity? Are you trying to provide power back in case of power failure? Or something else?
> 
> You need to watch and see how much power you use during the 4-9PM period. Is it more than the batteries can provide?
> 
> ...


Yes, intent is solely reduce cost and I set aside 20% of the storage for back-up. I have been running the battery in advance mode with it set to take over from 4PM-9PM for the last few days and at 9PM when I return to grid power I am sitting with @65% of my battery left. which is why I raised the question, should I keep going. By 9PM, on weekdays anyway, we are about to pack it in and the TVs and lights, etc go off and I suspect the batteries could probably handle things until 4-5AM if I let them run. I have all of my consumption data readily available via a download from my power company and my system produces significantly more than I consume. I have 43ea 435w panels and I produce 1800-2700 KWh per month and my consumption is from 1200-1600KWh per month (low figure winter/cloudy, high figure spring/summer sunny).


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## Ed Woodrick (May 26, 2018)

If you are producing more than you are earning, why are you worrying about switching back to external power?


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## 2Intense (May 3, 2021)

Ed Woodrick said:


> If you are producing more than you are earning, why are you worrying about switching back to external power?


To offset a portion of the consumption during PEAK rate period with stored power to reduce cost further.


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## Bigriver (Jan 26, 2018)

@2Intense, I'm also missing something in the basic question.

My understanding is that on an average basis your production is higher than your consumption by a pretty nice margin. You have Powerwalls with about 50 kWh of capacity, but arguably don't ever want to use all of that, as you want to maintain a reserve for power outages. You said that if you run on Powerwalls overnight that they will last until about 4 to 5 am. Thus you would have a few hours of having to pay $0.17/kWh until solar production comes back online and can meet your consumption. Wouldn't this always be preferable, to have a few hours at $0.17/kWh than about 10 hours at that rate? With your eco system being that you pay $0.17/kWh or $0.45/kWh vs getting paid $0.03/kWh, don't you always want to be using your own energy, only resorting to the grid when necessary, with priority of avoiding the peak rate?

Of course that is all in the average, and I know for me the devil is in the detail that not many days are average. I have day to day variations and season to season variations that would not give one answer. But my utility also credits me one for one with kWh sent to the grid with later pulling the kWh from the grid with no time of use factor. Thus, more and more I use the grid as if it were my very big Powerwall, saving my actual Powerwalls for backup. But for your situation, how often do you have a day where the Powerwalls would not get replenished enough to get you through the 4-9 pm peak period?


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## Ed Woodrick (May 26, 2018)

2Intense said:


> To offset a portion of the consumption during PEAK rate period with stored power to reduce cost further.


If you are producing 1800 kWh and using 1200 kWh. That suggest that you are using 24 kWh/day, only half of the battery pack. So I'm not sure why you would want to switch to the grid (except for quick recovery from low generation periods).

It sounds as if you can stay on battery 100% of the time. If you were using 1800 kWh and producing 1200 kWh, that would be another thing. But since you are producing more than you use. I'm really confused why you ever would switch to the grid. The grid is only there for selling excess power to.


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## welcht50 (8 mo ago)

2Intense said:


> I have a solar system as well as 4 Tesla Powerwalls and I am trying to come to terms with how I should be using Tesla's advanced mode option given my circumstances.
> First let me explain. I am on a TOU (Time of Use) rate plan with the power company. I pay a peak rate of $.45 per KWh from 4PM-9PM and a standard rate of $.17 per KWh the rest of the time. The NESCR (Net Energy Surplus Compensation Rate), or rate that I get reimbursed for the excess energy I produce and send back to the grid about $.03 per KWh. (varies between $.02-$.03 depending upon month).
> 
> If I run in advanced mode and have it set for the house to shift to battery power between 4PM-9PM I am consuming power I produced from solar and avoiding the $.45 per KWH period. At 9PM the batteries cease providing power and the house switches back to the grid and when the sun comes up, excess power that my solar produces will flow to top off the batteries before going to the grid. Then once the batteries are full, the overage goes back to the grid. My solar produces @ 85KWh of energy per day and consume @65 KWh per day. It's notable that about 50% of my consumption occurs during the peak period of 4PM-9PM.
> ...


So this is what you should do to maximize your solar.
I have a solar tile roof in orange county ca. Here's my issue: If I go off the grid I can be 100% solar powered. What this means however is that in the morning my battery level has dropped to about 40% so as the morning proceeds it charges back up to 98% and reaches 98% around 1 pm. If I stay off the grid, I stop generating any electricity from the roof. So I have to manually go into the app to go back on the grid and that triggers my roof to start producing energy again. That electricity goes back into the grid ( since my battery is full).

Now we are at 4 pm and since I elected TOU 4-9, the battery will begin depleting and feeding electricity back into the grid. Now after 9 pm it gets interesting because the system says "hey your battery is down to about 72% so let's go into the grid and get it charged back up" . So I literally have to go back into the app and go "off the grid" again so that my house runs only off the battery ( which it can do for a good 12-14 hrs) at which point in the morning I begin to charge the battery all over again as the sun comes out.

Here's the problem: 1) I have to remember to go into the app and turn "off the grid" around 1 pm to maximize the potential of the system. It blows me away that I can't program this to go on and off the grid at certain trigger points. 2) And this is important because if I don't switch "off the grid" at 9 pm I start paying for the energy at a rate of about $.33/kwh to charge the battery (which I don't need since I have enough storage to get me to the next morning ), while when I'm selling it back to the grid ( in that 1 pm to 9 pm period), I'm only reimbursed about $.04/kwh.
So there you have it. its a pain to do it and its not automated but that's how you maximize your system. Anyone have another, easier way?


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## welcht50 (8 mo ago)

Ed Woodrick said:


> If you are producing 1800 kWh and using 1200 kWh. That suggest that you are using 24 kWh/day, only half of the battery pack. So I'm not sure why you would want to switch to the grid (except for quick recovery from low generation periods).
> 
> It sounds as if you can stay on battery 100% of the time. If you were using 1800 kWh and producing 1200 kWh, that would be another thing. But since you are producing more than you use. I'm really confused why you ever would switch to the grid. The grid is only there for selling excess power to.


wouldn't you want to switch back to the grid to sell your excess energy back to the grid ( at a paltry rate compared to what you pay but nonetheless its something, right?)


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## Bigriver (Jan 26, 2018)

@welcht50, welcome to the forum.

I have a few thoughts/questions on your situation. First, as a preface, I have had solar for 4 years, Powerwalls for 3 years, and a TOU option is very new here (in western PA) so I have had that for less than a year. I do wish the app would give me the simplicity of setting priority of solar/grid/Powerwall throughout the day. But we don't have that explicit control. For awhile I also went in and changed my settings throughout the day to force it to do what I want.

I'm not sure the advantage of ever using the off grid option. With you having enough solar and Powerwall capacity to never need the grid, what if you used the "self powered" option and set the PW reserve to a low number. That would make solar supply your house while the sun is shining, would use the Powerwall as the secondary, and would send all excess to the grid (after PW is refilled each morning), never missing out on maximum solar production. What am I not seeing that would make this inadequate? Do you have the option/did you want to be sending back to the grid from the Powerwall ? Do you get paid different amounts for sending it back at different times of the day? (The answer to that is no here, we only get charged differently for using the grid.) Is what you pay/get paid the net total at the end of the billing cycle, or would drawing 10 kWh from the grid one day during peak result in charges for that, despite sending back 100 kWh during peak for the whole billing cycle?

You also noted that you don't want the grid to be filling your PW; we do have specific control over that….you can toggle "grid charging" to No.

The single control that I have currently been changing sometimes now is the PW reserve. That typically lets me alter the energy flow, which I sometimes do while charging a car. I don't see any point in depleting batteries to fill other batteries.


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## welcht50 (8 mo ago)

Bigriver said:


> @welcht50, welcome to the forum.
> 
> I have a few thoughts/questions on your situation. First, as a preface, I have had solar for 4 years, Powerwalls for 3 years, and a TOU option is very new here (in western PA) so I have had that for less than a year. I do wish the app would give me the simplicity of setting priority of solar/grid/Powerwall throughout the day. But we don't have that explicit control. For awhile I also went in and changed my settings throughout the day to force it to do what I want.
> 
> ...


Hey Big River
Thanks for your input. So I can go off the grid and self power, for sure but I'm not maximizing the value of the system meaning I could be selling excess power back to the grid. You see what happens is if I'm off the grid, by noon or so I have filled the PW and the system stops producing because the power has no place to go. At that point if I manually switch to get back on the grid, then I am feeding the grid to the tune of about 10 kwh a day. So about 1 pm I manually go back on the grid . Now here's the problem, if my PW drops to say 85 or 90 %, the grid starts feeding the PW until 4 pm-9pm which is my TOU and the system knows from 4-9 to not use the grid. But after 9, again if my PW is less than full, the gird starts filling it again. So at that point I manually take it off the grid because I have enough power in the PW to get me through to the next day. If I didn't do that the grid would keep my PW full all through the night which I don't need to do. You could think "well let the grid fill the PW and then in the morning when I'm producing power again, all that will be fed back into the grid but that doesn't make sense when you consider I'm charged $.33 kwh and I sell back at $.04 kwh. I hope all this makes sense. It seems to me that with the technical prowess of Telsa this would be much more automated or use AI to maximize the system. 
One more thing, they say don't charge your car to 100% so wouldn't that also apply to the PW. I notice that system tops me out at 98% on the PW and then stops producing if I stay off the gird.


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## Bigriver (Jan 26, 2018)

welcht50 said:


> So I can go off the grid and self power, for sure but I'm not maximizing the value of the system meaning I could be selling excess power back to the grid.


"Off grid" and "self powered" are 2 separate options in the app, so I'm not sure whether we are using the same terminology. At the main screen, there is:








And then in the settings, here is what I see:








If you use the settings I show above, it will let you use solar to power your house, excess recharges the Powerwalls, and then when Powerwalls are fully charged the excess will go to the grid. After the sun goes down it will use the Powerwalls overnight to power your house. It will never charge the Powerwalls from the grid. It does this without you having to change any settings at all during the day. Isn't this the basic functionality you are tying to achieve?


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## welcht50 (8 mo ago)

Bigriver said:


> "Off grid" and "self powered" are 2 separate options in the app, so I'm not sure whether we are using the same terminology. At the main screen, there is:
> View attachment 42593
> 
> And then in the settings, here is what I see:
> ...


I was on time based control not self powered. I just switched on the self powered so we'll see what happens. If that works, you are the man! Thanks, I'll keep you posted


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## welcht50 (8 mo ago)

welcht50 said:


> I was on time based control not self powered. I just switched on the self powered so we'll see what happens. If that works, you are the man! Thanks, I'll keep you posted


So I switched and it seems to be working pretty well but see attached screenshot. Why would it send power back to the grid when the power wall is only at 21%. Theoretically it should be trying to fill the pw as soon as possible to get it to capacity. It just does this sporadically so I don't know if that's a glitch in the system?


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## Bigriver (Jan 26, 2018)

welcht50 said:


> Why would it send power back to the grid when the power wall is only at 21%. Theoretically it should be trying to fill the pw as soon as possible to get it to capacity. It just does this sporadically so I don't know if that's a glitch in the system?


I have also seen brief strange energy flow in this graphic. I have never tried to trace down whether it is representing what the system is actually doing, or whether it is just a glitch in the representation of what the system is doing. I do know for sure that there is some sluggishness in what the app reports - for example I've had up to a 5 min delay before a grid outage was shown in the app.


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