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Optimizing PW TOU settings

Sep 24, 2015
835
698
San Diego (Oceanside)
Outside June - September, my rates are pretty much the same so I haven't really messed with TOU settings, but now that it's June I was playing around with them and not seeing results I expected.

peak 11a-6p M-F
semi peak 6a-11a, 6p-10p M-F
off peak 10p-6a

Peak and semi peak are basically the same rate (fraction of a penny difference) so let's just say 6a-10p is expensive and 10a-6a is half the cost.

I set 6a-10p as peak and set TOU as cost. I figured it would charge the PW on the weekends, then use PW at 6a until solar generated enough, then send excess solar to the grid, then go to grid power at 10p. In this scenario, the PW would maybe be used an hour in the AM and bout 7-10p. I figured the PW's had enough weekend power to cover that, but couldn't get that behavior. I saw TOU discharging PW during peak and sending all solar to grid. No, don't want that.

I switched to balanced. I figured this would do what I wanted. Nope, still discharged PW during the day and send solar to grid.

I used this guide (Powerwall Modes of Operation with Solar | Tesla Support Australia) and tried various settings (only setting off peak, leaving the rest as shoulder, etc.) but I couldn't get the behavior desired. The doc is for Australia, so maybe that's another issue.

Any TOU experts here have any suggestions for settings?

I'm hoping to charge the PW's fully on Sunday. I can run grid sundown to 6a Monday (off-peak), then use PW/solar until 10p weekdays. I do have automation via HomeAssistant that can switch modes on time based, so switching the PW to backup at 10p to force grid use and TOU at 6a is an available option. I just can't figure out how to get solar to power the house, then send excess to grid M-F. The PW's always start discharging during the day and all solar goes to grid.

Only thing I can think of it I have to let it do it's thing in TOU mode to learn for say a week.

thanks!
 

MJ_CA_2019

Member
Aug 19, 2020
159
43
Central CA
I saw TOU discharging PW during peak and sending all solar to grid. No, don't want that.
Can you explain why you don't want this?

The best way to price arbitrage is to send 100% of your PV generation to the grid during peak.

If you are net consumer during the summer (like I am) then the best TOU outcome is to 100% run the house off the PW during peak, and gain generation credits for every kWh generated by your PV. What wasn't intuitive to me is that when your peak ends... it's better to run off the grid until the sun comes back up... again if you are a NET CONSUMER during a given season.

If you are a net producer (like I am in the winter) then you should expect your self powered score to go way up and for very little grid draw to occur (like I did for essentially 3 months in the winter).

Hope this helps

Edited to add: on the weekends (I'm on PG&E TOU-B [off peak weekends]) I find that the system prioritized topping off the battery and then using any PV generation to minimize draw from the grid. In a Net consumer season this again is the best outcome. During Net Producer season I was effectively off grid.
 

RKCRLR

Member
Apr 13, 2020
465
190
Garden Valley, CA
Here's what I found:

Cost Saving:
Off Peak will prioritize all solar generation to recharging the Powerwalls. Once the the Powerwalls are charged, the house will run off the solar with excess sent to the grid. If there isn't enough solar to run the house then power will be drawn from the grid. The house will never run from the Powerwalls.
Shoulder will prioritize the house and send excess to the grid (depending on conditions). However, it will also draw from the grid is solar can't keep up (depending on conditions).
Peak will divert all solar generation to the grid and draw from the Powerwalls when solar can't keep up.

Balanced:
Off Peak will prioritize solar generation to the house and send excess to the grid depending on conditions. However, it will also draw from the Powerwalls down to the reserve depending on conditions.
Shoulder will prioritize solar to the house or to the grid, and draw from the Powerwalls or from the grid, depending on conditions.
Peak will send all solar generation to the grid and draw from the Powerwalls when solar can't keep up.

The gory details can be found in this thread:

Can you provide more details on how HomeAssistant works? I have dedicated CoreELEC (Kodi) home theater server than can run Entware packages. What would I use to interface with HomeAssistant? I'm not very good at command line stuff but I manage to stumble through it. Also, I have Python 3 installed on my CoreELEC box.
 
Last edited:
Mar 15, 2021
277
114
California
This table is one of the best I have seen summarizing the different modes
Capture.PNG
 
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ZTrekus

Member
Feb 8, 2015
874
113
Sydney, NSW
Can't we just please schedule a full charge every night on off peak? It seems so obvious to me. It's so darn frustrating that we either have to manually do this basic function each night or hack the darn thing.
 

astrorob

stealth performance M3
Aug 27, 2014
483
111
oakland, ca
@ZTrekus seems to be in Australia - charging the powerwall from the grid at off peak prices might be legal there? it's basically not legal in CA but might be in other places in the USA and abroad.

over here in the USA the default mode seems to be "charge only from solar if there is solar" due to the IRS's solar tax credit rules.

edit: see this thread:

 

h2ofun

Active Member
Aug 11, 2020
2,919
555
auburn, ca
@ZTrekus seems to be in Australia - charging the powerwall from the grid at off peak prices might be legal there? it's basically not legal in CA but might be in other places in the USA and abroad.

over here in the USA the default mode seems to be "charge only from solar if there is solar" due to the IRS's solar tax credit rules.

edit: see this thread:

No because Tesla is too lazy and will not engage grid charging for folks who worked with SGIP and are not taking ITC
 

holeydonut

Supporting Member
Supporting Member
Jun 27, 2020
2,104
1,486
East Bay NorCal
No because Tesla is too lazy and will not engage grid charging for folks who worked with SGIP and are not taking ITC


We need Biden to amend solar tax rules by executive order; tax people other than me more; hook up more federal money to fight forest fires; and find away around the Republican filibuster by like next week. Plz and thx.
 
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Sep 24, 2015
835
698
San Diego (Oceanside)
Can you explain why you don't want this?
To be honest, I'm not sure. I got used to operating in Self Consumption. In the "winter", the rates are basically the same off peak and semi peak (no peak in winter) and between solar and PW, I used 0 grid and sent plenty of excess to PoCo.

I have had it running in TOU / Cost for a week. It's been running grid from 10p to 6a, then charging the PW during shoulder ($.42919) until peak at 11a ($.42931) when it discharges until 6p shoulder ($.42919 again) until 10, except on Friday where it discharges PW all day until it hits reserve or 10p as it knows it can charge up on Saturday for off peak.

Since shoulder and peak are pretty much the same price, it's charging in the AM at $.42 so it can run on battery during peak for $.42. I'm not sure what I am accomplishing here except saving $0.00012 /kwh for 7 hours a day.

Following the math isn't my strong point in this scenario, but it seemed like topping off PW on the weekend and using solar to power the house, then PW to power the house post solar until 10p every day would be a better use of weekend ($.0.25403) stored energy. I'd be not sending about 0.8 kw per hour self consuming solar during the day and powering the house sundown to 10 with weekend energy ($.0.25403).
 

Redhill_qik

Member
Aug 16, 2020
313
222
South SF Bay, California
To be honest, I'm not sure. I got used to operating in Self Consumption. In the "winter", the rates are basically the same off peak and semi peak (no peak in winter) and between solar and PW, I used 0 grid and sent plenty of excess to PoCo.

I have had it running in TOU / Cost for a week. It's been running grid from 10p to 6a, then charging the PW during shoulder ($.42919) until peak at 11a ($.42931) when it discharges until 6p shoulder ($.42919 again) until 10, except on Friday where it discharges PW all day until it hits reserve or 10p as it knows it can charge up on Saturday for off peak.

Since shoulder and peak are pretty much the same price, it's charging in the AM at $.42 so it can run on battery during peak for $.42. I'm not sure what I am accomplishing here except saving $0.00012 /kwh for 7 hours a day.

Following the math isn't my strong point in this scenario, but it seemed like topping off PW on the weekend and using solar to power the house, then PW to power the house post solar until 10p every day would be a better use of weekend ($.0.25403) stored energy. I'd be not sending about 0.8 kw per hour self consuming solar during the day and powering the house sundown to 10 with weekend energy ($.0.25403).
The Powerwall charging efficiency is around 90% so you are losing money with that tiny $0.00012 differential.
 

MJ_CA_2019

Member
Aug 19, 2020
159
43
Central CA
To be honest, I'm not sure. I got used to operating in Self Consumption. In the "winter", the rates are basically the same off peak and semi peak (no peak in winter) and between solar and PW, I used 0 grid and sent plenty of excess to PoCo.

I have had it running in TOU / Cost for a week. It's been running grid from 10p to 6a, then charging the PW during shoulder ($.42919) until peak at 11a ($.42931) when it discharges until 6p shoulder ($.42919 again) until 10, except on Friday where it discharges PW all day until it hits reserve or 10p as it knows it can charge up on Saturday for off peak.

Since shoulder and peak are pretty much the same price, it's charging in the AM at $.42 so it can run on battery during peak for $.42. I'm not sure what I am accomplishing here except saving $0.00012 /kwh for 7 hours a day.

Following the math isn't my strong point in this scenario, but it seemed like topping off PW on the weekend and using solar to power the house, then PW to power the house post solar until 10p every day would be a better use of weekend ($.0.25403) stored energy. I'd be not sending about 0.8 kw per hour self consuming solar during the day and powering the house sundown to 10 with weekend energy ($.0.25403).
Can you provide your full rate schedule? I'm not fully following you because I don't see an Off-Peak period.
Thx!
 

MJ_CA_2019

Member
Aug 19, 2020
159
43
Central CA
attached.
Thanks! this is helpful for the context and what you have observed.

Unfortunately it doesn't appear that you don't have any time that is "off peak" that would have any PV generation.
If your price difference between semi-peak and peak is not much then the TOU really isn't providing you any price arbitrage benefit.

Here's what I would expect out of Advanced / Balanced with all three (off peak, shoulder, peak) configured.

One Day Example:
Summer (when you are a net consumer)
0000 - 0600 "Off peak" - home 100% run by grid
0600 - 1100 "Shoulder" - home run by grid while 100% of PV goes to PW until fully charged; afterwards, PV used to lower grid draw / excess exported
1100 - 1800 "Peak" - home 100% run by PW, 100% of PV goes to the grid
1800 - 2200 "Shoulder - home 100% run by grid, 100% of PV goes to PW until it reaches 100% (and if it reaches it PV used to lower grid draw)
2200 - 2400 "Off Peak" - home 100% run by grid

If you want to continue to play around with Advanced modes, here's what I would try:

Week (M-F)
Off-peak (blue)
10 pm - 6 am
Shoulder (gray)
6 am - 10 pm
Peak (yellow)
None

You may need to set a peak period and then uncheck the peak period in order to create the shoulder (gray) period in this time frame.

This SHOULD tell the system to power the home with PV and send excess to the PW. Depending on your total home usage and PV generation the system might draw from the grid OR PW when home use exceeds PV. Once PV reaches 100% then excess would be exported.

Good Luck!
 
Sep 24, 2015
835
698
San Diego (Oceanside)
Thanks for your detailed reply. I'll switch to balanced and observe what happens and adjust the peak/shoulder if necessary.

Weekends are off peak all day. I was hoping it would use PV to power the house first, then to realize that there's no good weekday time to charge but use 15-20% a day from PW during shoulder when there's no PV, then top it off on Saturday again.

This is the least year I'll have this TOU. I'll be forced to the standard 4a-9p peak next year, so this scenario won't really matter but it's fun to learn how the system behaves.

thanks again!
 

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