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Are these operating modes possible?

RKCRLR

Member
Apr 13, 2020
437
171
Garden Valley, CA
This will be highly dependent on house load during peak and the PV size. For my own personal situation, during the winter I encounter only 2 days where my PWs did not fully charge before Peak.

This should be the AI learned function that is Balanced. Understanding your house load during peak plus the expected weather and PV generation. My sprinkler system knows the weather and adjusts the watering timer, big data Tesla should be able to do the same.
I'd probably like balanced if it had an option to never discharge the Powerwall during off-peak hours.
 

Redhill_qik

Member
Aug 16, 2020
307
217
South SF Bay, California
You are "banking" low cost kWhs into the PW. During peak, you want to power house from PW and send solar to grid at the Peak rates. That is where the cost savings occurs.
Your cost analysis is faulty.

The PWs will charge and excess solar will be exported at the same Off-Peak rate and should be at 100% from sunrise until 3pm (EV2), 4pm (E-TOU-C) or 5pm (E-TOU-D) before either Partial Peak (EV2A) or Peak (E-TOU-C/D) rates start. My PWs are fully charged by noon and never get close to the either the partial or peak times.

As an example, today my PWs imported 12.20 kWh and were 100% full at 12:00pm using Balanced with overcast skies and during this period the house load was 3.65 kWh. If I was using the Cost Savings mode with 100% solar to PWs then the PWs would have been charged by 11:20am and the house would have consumed 3.12 kWh from the grid and incurred NBCs under NEM 2.0 which might be full rate under NEM 3.0.

Costs savings are most with having PWs take over the house load during Peak and Partial Peak times (EV2), but additional savings can be had with managing the recharge from solar during Off-Peak.
 

getakey

Active Member
Jan 28, 2020
1,322
429
95762
Your cost analysis is faulty.

The PWs will charge and excess solar will be exported at the same Off-Peak rate and should be at 100% from sunrise until 3pm (EV2), 4pm (E-TOU-C) or 5pm (E-TOU-D) before either Partial Peak (EV2A) or Peak (E-TOU-C/D) rates start. My PWs are fully charged by noon and never get close to the either the partial or peak times.

As an example, today my PWs imported 12.20 kWh and were 100% full at 12:00pm using Balanced with overcast skies and during this period the house load was 3.65 kWh. If I was using the Cost Savings mode with 100% solar to PWs then the PWs would have been charged by 11:20am and the house would have consumed 3.12 kWh from the grid and incurred NBCs under NEM 2.0 which might be full rate under NEM 3.0.

Costs savings are most with having PWs take over the house load during Peak and Partial Peak times (EV2), but additional savings can be had with managing the recharge from solar during Off-Peak.
how is it faulty?
I specifically said you want to power the house from PWs during peak which allows solar to export at Peak rates until sunset and avoid using grid during the remainder of the Peak. Depending on your rate plan, you will be charging the PWs at Off or Partial peak. Therefore your savings is that differential (Peak - Off or Peak - partial) for the amount of kWhs pulled from the PWs minus the 10% round trip loss.
 

arnolddeleon

Supporting Member
Jul 21, 2012
842
910
SF Bay Area
I tried balanced but it will discharge the Powerwalls during off-peak which is not what I want.
Oh, sorry, I misread/understood your original post.

I think what you want is to use "cost savings" with a fake shoulder (part peak) during your solar hours. I think this will come closest to what you want.

BTW if you are trying to minimize your costs and you have NBCs, balanced might ende up working slightly better (if you have enough batteries). With my recent PV and battery upgrade I'm now able to run self powered over 95% during the summer (I only have 2 months of experience so far with it). I'm banking credits that I will need for winter (I heat with a heat pump) so I'm trying to minimize my NBCs by having the Powerwalls discharge. Basically I'm willing to burn "over production" in the summer to avoid NBCs.
 

RKCRLR

Member
Apr 13, 2020
437
171
Garden Valley, CA
Oh, sorry, I misread/understood your original post.

I think what you want is to use "cost savings" with a fake shoulder (part peak) during your solar hours. I think this will come closest to what you want.

BTW if you are trying to minimize your costs and you have NBCs, balanced might ende up working slightly better (if you have enough batteries). With my recent PV and battery upgrade I'm now able to run self powered over 95% during the summer (I only have 2 months of experience so far with it). I'm banking credits that I will need for winter (I heat with a heat pump) so I'm trying to minimize my NBCs by having the Powerwalls discharge. Basically I'm willing to burn "over production" in the summer to avoid NBCs.
I'm trying to understand how the fake shoulder would help.

I'm on cost savings, have 9.6kW solar, 2 Powerwall 2s, and set my reserve at 50% for power outages. I'm on EV2A and it has become apparent I'm going to overshoot my goal of $0 true-up. I decided to remove my shoulder rate to and leave my peak to match the EV2A peak hours from 4pm to 9pm. On hot summer afternoons I can usually make it all the way through peak hours before I hit my reserve and am usually recharged before 11am.

Are you saying to add a fake shoulder or change my peak to shoulder?

My goal at this point is to reduce NBCs and minimize Powerwall cycles. I'll have to monitor to see where I'm at in relation to my goal of $0 true-up in September.
 

Redhill_qik

Member
Aug 16, 2020
307
217
South SF Bay, California
how is it faulty?
I specifically said you want to power the house from PWs during peak which allows solar to export at Peak rates until sunset and avoid using grid during the remainder of the Peak. Depending on your rate plan, you will be charging the PWs at Off or Partial peak. Therefore your savings is that differential (Peak - Off or Peak - partial) for the amount of kWhs pulled from the PWs minus the 10% round trip loss.
Please go back and read the original post and my replies as you are focused on Peak discharge and the discussion is on Off-Peak recharge.

  1. Both Cost Saving and Balanced modes will power the house loads during the peak periods will 100% of the solar going to the grid which is what everyone agrees on should be done for maximum cost savings
  2. The Balanced mode will power the house loads at sunrise and recharge the PWs with the excess first and after the PWs are at 100% will send the rest to the grid which is what @RKCRLR and I want for maximum cost savings
  3. The Balanced mode will continue to discharge the PWs in Off Peak which neither @RKCRLR nor I want to have happen which requires more solar to be used for recharging due to 90% efficiency leaving less to be exported reducing cost savings through less exports
  4. The Cost Saving mode will recharge the PWs with 100% solar at sunrise and with the house loads imported from the grid which reduces cost cost savings through NBCs
I want to have 1 and 2 without 3 or 4. I can get there by going into the app twice a day to switch the mode and it can likely be automated through the API, but that requires a lot more effort than just providing more control in the app that anyone can select.
 
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RKCRLR

Member
Apr 13, 2020
437
171
Garden Valley, CA
  1. Both Cost Saving and Balanced modes will power the house loads during the peak periods will 100% of the solar going to the grid which is what everyone agrees on should be done for maximum cost savings
Cost Saving mode will send 100% of the solar to the grid and run the home off the Powerwalls during peak. I was also also looking for a setting that would prioritize the home during peak and send the excess to the grid (and run the home off the Powerwalls when there is insufficient solar). Does Balanced act that way during peak?
 

getakey

Active Member
Jan 28, 2020
1,322
429
95762
Please go back and read the original post and my replies as you are focused on Peak discharge and the discussion is on Off-Peak recharge.

  1. Both Cost Saving and Balanced modes will power the house loads during the peak periods will 100% of the solar going to the grid which is what everyone agrees on should be done for maximum cost savings
  2. The Balanced mode will power the house loads at sunrise and recharge the PWs with the excess first and after the PWs are at 100% will send the rest to the grid which is what @RKCRLR and I want for maximum cost savings
  3. The Balanced mode will continue to discharge the PWs in Off Peak which neither @RKCRLR nor I want to have happen which requires more solar to be used for recharging due to 90% efficiency leaving less to be exported reducing cost savings through less exports
  4. The Cost Saving mode will recharge the PWs with 100% solar at sunrise and with the house loads imported from the grid which reduces cost cost savings through NBCs
I want to have 1 and 2 without 3 or 4. I can get there by going into the app twice a day to switch the mode and it can likely be automated through the API, but that requires a lot more effort than just providing more control in the app that anyone can select.
here's the second part of your original post:

"During peak I'd like the house to run off solar with the excess going to the grid with the house running off the Powerwalls (until the reserve is hit) when there isn't sufficient solar; and the Powerwalls are NEVER recharged during this period."

running the house off solar during Peak does not maximize savings
 

RKCRLR

Member
Apr 13, 2020
437
171
Garden Valley, CA
here's the second part of your original post:

"During peak I'd like the house to run off solar with the excess going to the grid with the house running off the Powerwalls (until the reserve is hit) when there isn't sufficient solar; and the Powerwalls are NEVER recharged during this period."

running the house off solar during Peak does not maximize savings
That is my post and let me clarify why I'm asking.

I agree that running the house off solar during peak does not maximize savings as long as NBCs, Powerwall cycle life, and the ~$0.03/kWh wholesale rate you are compensated for excess generation aren't taken into account.

Once you have reached the point where you are going to have excess generation at true-up, my opinion is you are better off reducing NBCs and Powerwall cycles instead of being paid $0.03/kWh.
 

Redhill_qik

Member
Aug 16, 2020
307
217
South SF Bay, California
here's the second part of your original post:

"During peak I'd like the house to run off solar with the excess going to the grid with the house running off the Powerwalls (until the reserve is hit) when there isn't sufficient solar; and the Powerwalls are NEVER recharged during this period."

running the house off solar during Peak does not maximize savings
Ok, egg on my face. 😊

I only want the first part of the original post about the Off Peak recharge behavior. Peak should be 100% PW.

In my prior post 1 and 2, not 3 or 4.
 

getakey

Active Member
Jan 28, 2020
1,322
429
95762
That is my post and let me clarify why I'm asking.

I agree that running the house off solar during peak does not maximize savings as long as NBCs, Powerwall cycle life, and the ~$0.03/kWh wholesale rate you are compensated for excess generation aren't taken into account.

Once you have reached the point where you are going to have excess generation at true-up, my opinion is you are better off reducing NBCs and Powerwall cycles instead of being paid $0.03/kWh.

ok, excess generation changes things a lot. I have zero NEM charges, but still a net user (not an excess generator)
 

RKCRLR

Member
Apr 13, 2020
437
171
Garden Valley, CA
Cost Saving mode will send 100% of the solar to the grid and run the home off the Powerwalls during peak. I was also also looking for a setting that would prioritize the home during peak and send the excess to the grid (and run the home off the Powerwalls when there is insufficient solar). Does Balanced act that way during peak?
If I were to remain in Cost Savings mode but change my current peak hours of 4pm to 9pm to partial peak, how should I expect the system to react?
Would solar be prioritized to my home and then the grid? Would my system draw from the grid during this period (don't want that)?
 

tomuo

Member
Mar 15, 2021
35
10
Los Angeles, CA
What does your analysis look like if you go real simple, setting to Self-Powered for the whole year?
Maybe you just need to be in Self-Powered for the summer months, and balanced for the rest?

It's possible to automate changing the reserve level to force export/import on a schedule with a Raspberry Pi, but it may be possible to automate changing the entire mode too.
 

RKCRLR

Member
Apr 13, 2020
437
171
Garden Valley, CA
What does your analysis look like if you go real simple, setting to Self-Powered for the whole year?
Maybe you just need to be in Self-Powered for the summer months, and balanced for the rest?

It's possible to automate changing the reserve level to force export/import on a schedule with a Raspberry Pi, but it may be possible to automate changing the entire mode too.
From what I understand, self-powered will use the Powerwalls at night which I don't want to do. And there is no option for peak periods, and I definitely don't want to draw from the grid during peak periods unless I've hit my reserve.
 

arnolddeleon

Supporting Member
Jul 21, 2012
842
910
SF Bay Area
I'm trying to understand how the fake shoulder would help.

I'm on cost savings, have 9.6kW solar, 2 Powerwall 2s, and set my reserve at 50% for power outages. I'm on EV2A and it has become apparent I'm going to overshoot my goal of $0 true-up. I decided to remove my shoulder rate to and leave my peak to match the EV2A peak hours from 4pm to 9pm. On hot summer afternoons I can usually make it all the way through peak hours before I hit my reserve and am usually recharged before 11am.

Are you saying to add a fake shoulder or change my peak to shoulder?

My goal at this point is to reduce NBCs and minimize Powerwall cycles. I'll have to monitor to see where I'm at in relation to my goal of $0 true-up in September.
I would set it up as follows:

Off peak: midnight to 7:00 am (something approximating beginning of solar production)
Part peak: 7:00 am to 4:00 pm
Peak 4:00 pm to 9:00 pm
Part peak 9:00 pm to Midnight

What I would expect to happen is that system will charge in the morning from excess solar so you should be close to zero grid usage until the Powerwalls are full. After that, all the excess will get exported. When peak time starts the Powerwalls should start discharging.

There is chance that the system will refuse to discharge during the evening part peak (because it "thinks" the energy came from part peak as well). Possible fix for that is to stretch the peak hours to cover. The other possible fix is try it balanced mode. Because balanced is trying to for self consumption it is more willing to discharge energy that came from the same rate period. It still won't discharge during off peak because all of your stored energy is "part peak".
 
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RKCRLR

Member
Apr 13, 2020
437
171
Garden Valley, CA
I would set it up as follows:

Off peak: midnight to 7:00 am (something approximating beginning of solar production)
Part peak: 7:00 am to 4:00 pm
Peak 4:00 pm to 9:00 pm
Part peak 9:00 pm to Midnight

What I would expect to happen is that system will charge in the morning from excess solar so you should be close to zero grid usage until the Powerwalls are full. After that, all the excess will get exported. When peak time starts the Powerwalls should start discharging.

There is chance that the system will refuse to discharge during the evening part peak (because it "thinks" the energy came from part peak as well). Possible fix for that is to stretch the peak hours to cover. The other possible fix is try it balanced mode. Because balanced is trying to for self consumption it is more willing to discharge energy that came from the same rate period. It still won't discharge during off peak because all of your stored energy is "part peak".
I don't think that will do what I want.
It is still set to peak from 4pm to 9pm so it will still divert all solar to the grid during that period. I want the house to be the priority during that period with the excess going to the grid during that period.
I want all power to come from the grid after 9pm.

Basically, I'd like the system to act like it was solar with no batteries with the following exceptions:

1) During the peak hours of 4pm to 9pm the Powerwalls supplement any house demands that the solar can't provide.

2) The following morning, any excess solar energy that the house doesn't consume is used to recharge the batteries. However, if the system recognizes that the Powerwalls won't get fully recharged before the next 4pm peak start, it prioritizes recharging the Powerwalls over house consumption.
 

getakey

Active Member
Jan 28, 2020
1,322
429
95762
I don't think that will do what I want.
It is still set to peak from 4pm to 9pm so it will still divert all solar to the grid during that period. I want the house to be the priority during that period with the excess going to the grid during that period.
I want all power to come from the grid after 9pm.

Basically, I'd like the system to act like it was solar with no batteries with the following exceptions:

1) During the peak hours of 4pm to 9pm the Powerwalls supplement any house demands that the solar can't provide.

2) The following morning, any excess solar energy that the house doesn't consume is used to recharge the batteries. However, if the system recognizes that the Powerwalls won't get fully recharged before the next 4pm peak start, it prioritizes recharging the Powerwalls over house consumption.
Have you gone through a true up yet or is your PW install fairly new?
Or, Do you have any bills that show cumulative NEM to date?
 

h2ofun

Active Member
Aug 11, 2020
2,684
492
auburn, ca
I would set it up as follows:

Off peak: midnight to 7:00 am (something approximating beginning of solar production)
Part peak: 7:00 am to 4:00 pm
Peak 4:00 pm to 9:00 pm
Part peak 9:00 pm to Midnight

What I would expect to happen is that system will charge in the morning from excess solar so you should be close to zero grid usage until the Powerwalls are full. After that, all the excess will get exported. When peak time starts the Powerwalls should start discharging.

There is chance that the system will refuse to discharge during the evening part peak (because it "thinks" the energy came from part peak as well). Possible fix for that is to stretch the peak hours to cover. The other possible fix is try it balanced mode. Because balanced is trying to for self consumption it is more willing to discharge energy that came from the same rate period. It still won't discharge during off peak because all of your stored energy is "part peak".
I use no part peak. Just peak and off peak. Works perfectly
 

RKCRLR

Member
Apr 13, 2020
437
171
Garden Valley, CA
Have you gone through a true up yet or is your PW install fairly new?
Or, Do you have any bills that show cumulative NEM to date?
I had my solar installed September 2019. I got Powerwalls a year ago in June. I had a $200 credit for excess generation at my true-up last September. I will likely cross over to net surplus this month (I owed $66 cumulative in my last statement).
 

getakey

Active Member
Jan 28, 2020
1,322
429
95762
I had my solar installed September 2019. I got Powerwalls a year ago in June. I had a $200 credit for excess generation at my true-up last September. I will likely cross over to net surplus this month (I owed $66 cumulative in my last statement).
OK, so your new true up with PWs will be this month?
 

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