Balanced not discharging to reserve

[MJ_CA_2019]

We recently reached the switch over to AC season and using more than we produce. I’m about half way through year two with PW and last summer I did a lot of switching modes and reserve %.

my expectation is that balanced should discharge my PW down to the reserve before going to standby. Also it seems like my system is using the grid too much. What say you?



PS: TOU-B, 12.6 kW (dc) system and 3 PW on 10% reserve.

 

[MJ_CA_2019]

This is yesterday. Why draw so much from the grid when overall there was a minor difference between PV production and usage?

 

[Redhill_qik]

Looks like you are in Cost Saving mode instead of Balance as the Powerwalls are discharging for the entire peak period and when they start to recharge in the morning 100% of the solar is going to the recharging the Powerwalls. This may just be the Balanced "smarts" that is looking at your consumption of 85.6 kWhs and the PV generation of 65.6 kWH and deciding that it needs to push everything to the PWs in order to get back to 100% before the peak period which it does around 1:30pm.

Why are you importing so much from the grid? It's because your house loads are consuming for 24 hours while the PWs are covering for 5 hours and the Solar is only generating for 13.5 hours with the first 7 hours spent recharging the PWs, the next 2.5 hours are partially powering the house with some exports and the last 4 hours is all exports as the PWs are powering the house. If your goal is less imports than you want to switch to Self-Powered mode.

 

[miimura]

You only have Peak and Off-Peak defined. If you want it to use the grid less on either side of the Peak period, reduce the Off-Peak hours so that there is some shoulder period in the Powerwall schedule.

I am on EV2-A and if there is sufficient energy, TBC-Balanced Mode will continue to power the house through the Part-Peak hours from 9pm-midnight.

 

[MJ_CA_2019]

Looks like you are in Cost Saving mode instead of Balance as the Powerwalls are discharging for the entire peak period and when they start to recharge in the morning 100% of the solar is going to the recharging the Powerwalls. This may just be the Balanced "smarts" that is looking at your consumption of 85.6 kWhs and the PV generation of 65.6 kWH and deciding that it needs to push everything to the PWs in order to get back to 100% before the peak period which it does around 1:30pm.

Why are you importing so much from the grid? It's because your house loads are consuming for 24 hours while the PWs are covering for 5 hours and the Solar is only generating for 13.5 hours with the first 7 hours spent recharging the PWs, the next 2.5 hours are partially powering the house with some exports and the last 4 hours is all exports as the PWs are powering the house. If your goal is less imports than you want to switch to Self-Powered mode.

I'm not on Cost Savings, it's on Balanced.

Self-Powered Mode won't help with TOU price arbitraging.

You only have Peak and Off-Peak defined. If you want it to use the grid less on either side of the Peak period, reduce the Off-Peak hours so that there is some shoulder period in the Powerwall schedule.

I am on EV2-A and if there is sufficient energy, TBC-Balanced Mode will continue to power the house through the Part-Peak hours from 9pm-midnight.

I can try to define shoulder (part-peak) but I thought the point of Balanced was to increase my self powered score.
I get that energy forecast might want to store more PV energy early in the day to make sure that the battery has enough to get through peak, this this seems like the worst of both behaviors. Extra grid draw to top of the battery then not taking advantage of the capacity I told it to use.

 

[skepticcyclist]

We recently reached the switch over to AC season and using more than we produce. I’m about half way through year two with PW and last summer I did a lot of switching modes and reserve %.

my expectation is that balanced should discharge my PW down to the reserve before going to standby. Also it seems like my system is using the grid too much. What say you?



PS: TOU-B, 12.6 kW (dc) system and 3 PW on 10% reserve.

Holy crap, that is a lot of electricity. How can a house possible use that much? The highest we get is about 4kw at any one time, that's with the AC running with the microwave. With our pool pump running and the AC we may also get to 4kw. With the AC or pool pump our house is usually running about 2.5kw. As I am typing this on a computer using about 800 watts and the pool pump on and we are using 2.9 kw. Outside of that that our house usually maintains about 200-500 watts at any one time

 

[skepticcyclist]

I'm not on Cost Savings, it's on Balanced.

Self-Powered Mode won't help with TOU price arbitraging.


I can try to define shoulder (part-peak) but I thought the point of Balanced was to increase my self powered score.
I get that energy forecast might want to store more PV energy early in the day to make sure that the battery has enough to get through peak, this this seems like the worst of both behaviors. Extra grid draw to top of the battery then not taking advantage of the capacity I told it to use.

Both cost saving AND balanced will use the battery during the peak. If you want to use solar AND only have the battery supplement additional power over what solar is producing, then set part of your peak period to partial peak and use balanced. The only difference in behavior between balanced and cost savings is during the partial peak period. The both behave the same during peak period

I currently set mine so the first half of my peak is partial peak

As you can see I only use solar until the house demand exceeds it. Then the battery makes up the difference.

 

[MJ_CA_2019]

Holy crap, that is a lot of electricity. How can a house possible use that much? The highest we get is about 4kw at any one time, that's with the AC running with the microwave. With our pool pump running and the AC we may also get to 4kw. With the AC or pool pump our house is usually running about 2.5kw. As I am typing this on a computer using about 800 watts and the pool pump on and we are using 2.9 kw. Outside of that that our house usually maintains about 200-500 watts at any one time

Two story 3000 sq ft house built in 2005 with average insulation. Second story about 50% of the square footage has vaulted ceilings.
Two original inefficient ACs, Single Speed Pool pump, etc.

BTW, to qualify for SGIP large scale I had to show that i could pull 15 kW from the grid. I turned everything on (including jet tub, hair dryers etc. and pulled about 18 kW)

 

[MJ_CA_2019]

Both cost saving AND balanced will use the battery during the peak. If you want to use solar AND only have the battery supplement additional power over what solar is producing, then set part of your peak period to partial peak and use balanced. The only difference in behavior between balanced and cost savings is during the partial peak period. The both behave the same during peak period

I currently set mine so the first half of my peak is partial peak

As you can see I only use solar until the house demand exceeds it. Then the battery makes up the difference.

I want my entire peak period (4-9 pm M-F) to be peak.
What I'm not understanding is why the system is:

1. Continuing to pull 100% of my home load from the grid until the battery is 100%. Yesterday the system started exporting to the grid at 2:00 pm which is 2 hours before the peak period started. Clearly the grid draw could have been less over the course of the day yesterday.
2. Why the system stopped using the battery at the end of peak with 36% reserve left and I've defined only 10% reserve.

I guess the result today SHOULD be that the battery should reach 100% much earlier in the day and I'll start to export sooner.
I've tried hard mentally to get past NBCs but this behavior seems to be sub-optimal.


Here's another way to think about it...
My Self Powered score from yesterday was 45% but my PV generation was 70% of my energy usage.
That seems like a very poorly written algorithm.

By comparison:

Monday 5/31 - Self Powered 67% - Energy Offset 75%
Tuesday 6/1 - Self Powered 66% - Energy Offset 93%
Wednesday 6/2 - Self Powered 45% - Energy Offset 70%

 

[h2ofun]

Two story 3000 sq ft house built in 2005 with average insulation. Second story about 50% of the square footage has vaulted ceilings.
Two original inefficient ACs, Single Speed Pool pump, etc.

BTW, to qualify for SGIP large scale I had to show that i could pull 15 kW from the grid. I turned everything on (including jet tub, hair dryers etc. and pulled about 18 kW)

Kids play, when I loaded up for SGIP, I pulled 35.3 But since I had only put in for 5, I could not get the 7

 

[skepticcyclist]

I want my entire peak period (4-9 pm M-F) to be peak.
What I'm not understanding is why the system is:

1. Continuing to pull 100% of my home load from the grid until the battery is 100%. Yesterday the system started exporting to the grid at 2:00 pm which is 2 hours before the peak period started. Clearly the grid draw could have been less over the course of the day yesterday.
2. Why the system stopped using the battery at the end of peak with 36% reserve left and I've defined only 10% reserve.

I guess the result today SHOULD be that the battery should reach 100% much earlier in the day and I'll start to export sooner.
I've tried hard mentally to get past NBCs but this behavior seems to be sub-optimal.

1. If you have it set to balanced, that shouldn't happen. This is more how cost savings operates, not balanced. It could be because it takes so long before you get to 100% charge that the algorithm is prioritizing charging your battery first (acting more like cost savings)?
2. This is normal. At the end of peak you will use grid power. That 26% additional charge above your 10% will be used at times outside of peak based on how your system runs on the average. The gateway will learn your usage pattern and use that additional 26% based when it thinks you need it the most during the off peak period

 

[h2ofun]

1. If you have it set to balanced, that shouldn't happen. This is more how cost savings operates, not balanced. It could be because it takes so long before you get to 100% charge that the algorithm is prioritizing charging your battery first (acting more like cost savings)?
2. This is normal. At the end of peak you will use grid power. That 26% additional charge above your 10% will be used at times outside of peak based on how your system runs on the average. The gateway will learn your usage pattern and use that additional 26% based when it thinks you need it the most during the off peak period

Am on balanced. I have peak set to 3 pm to 1am. No partial. My batteries do 100% during peak, about continue will into non peak. Will only pull from the grid when it has "learned" what the solar pattern is and makes sure they are at 100% before 3. I just leave things alone!!

 

[MJ_CA_2019]

1. If you have it set to balanced, that shouldn't happen. This is more how cost savings operates, not balanced. It could be because it takes so long before you get to 100% charge that the algorithm is prioritizing charging your battery first (acting more like cost savings)?
2. This is normal. At the end of peak you will use grid power. That 26% additional charge above your 10% will be used at times outside of peak based on how your system runs on the average. The gateway will learn your usage pattern and use that additional 26% based when it thinks you need it the most during the off peak period

Re: #2 - That is what I'm expecting. But our system was installed in Dec of 2019 so we have already been through one summer. We did have a jump to hellish temperatures in the past few days, but I was expecting the system to be smarter than this based on last year's data. 100% of my home loads came from the grid starting at 9:00 pm last night and continuing on to right now (14.6 kWh taken from grid already today). Battery is at 48% and climbing. I only need about 25 kWh to get through peak period, so would technically only need to get to about 70% of battery capacity to cover the peak period above my reserve.

This does not seem to be the goal of the algorithm. The goal seems to be to get the battery to 100% each day no matter what.

 

[h2ofun]

Re: #2 - That is what I'm expecting. But our system was installed in Dec of 2019 so we have already been through one summer. We did have a jump to hellish temperatures in the past few days, but I was expecting the system to be smarter than this based on last year's data. 100% of my home loads came from the grid starting at 9:00 pm last night and continuing on to right now (14.6 kWh taken from grid already today). Battery is at 48% and climbing. I only need about 25 kWh to get through peak period, so would technically only need to get to about 70% of battery capacity to cover the peak period above my reserve.

This does not seem to be the goal of the algorithm. The goal seems to be to get the battery to 100% each day no matter what.

Yes, I assume the battery is assumed to always have to get to 100% before peak. That is what I have seen

 

[MJ_CA_2019]

Yes, I assume the battery is assumed to always have to get to 100% before peak. That is what I have seen

So during the winter when you are in the same Generation to Usage deficit, did you have this same behavior?
100% of your home loads on the grid until the battery reached 100%? Was that even possible in a single day for you?
I'm guessing you had days where you ran 100% off the grid because of how much ESS capacity you need to fill?

 

[h2ofun]

So during the winter when you are in the same Generation to Usage deficit, did you have this same behavior?
100% of your home loads on the grid until the battery reached 100%? Was that even possible in a single day for you?
I'm guessing you had days where you ran 100% off the grid because of how much ESS capacity you need to fill?

I got my batteries installed in March. Since I use LOTS in winter with new heat pumps, and produce so much less solar, I have yet to figure out what I will do.
But clearly, will have to pull from grid more. Now, if I get the additional 15K of panels, even though most are poorly faced direction, meaning north, this will not help me as much, but until I get data and try, not sure. I just do not want to have to pull from grid when expensive. So, maybe I just charge the batteries in winter from the grid, when I do not have enough solar, and do when the cost is low.

 

[MJ_CA_2019]

It’s 11:43 and the battery is at 72%.
we will see when we start exporting today.

 

[h2ofun]

It’s 11:43 and the battery is at 72%.
we will see when we start exporting today.

I have one at 82, one at 65. 100% solar is house and batteries. Until 100% battery charge, I have not seen any solar exported

 

[skepticcyclist]

It’s 11:43 and the battery is at 72%.
we will see when we start exporting today.

It appears that your system is charging priority based on use and is using grid to supplement to ensure your batteries are full before peak.

This person made a spreadsheet summarizing the behavior in different modes better than what is explained on the Tesla site

 

[miimura]

So during the winter when you are in the same Generation to Usage deficit, did you have this same behavior?
100% of your home loads on the grid until the battery reached 100%? Was that even possible in a single day for you?
I'm guessing you had days where you ran 100% off the grid because of how much ESS capacity you need to fill?

I use Balanced. In the Winter when the solar production is low, it will completely power the house from the grid during Off-Peak and Part-Peak. It will put All Solar into the batteries until Peak starts, then during Peak it will power the house and export All Solar until the Reserve is reached. As the seasons change and the solar production becomes greater than the Peak consumption, it will start to discharge into Part-Peak period after Peak. Further increases in solar production will change the charging behavior to Surplus Solar instead of All Solar once it thinks it can reach 100% before the start of Part-Peak at 3pm.

Winter example:

Spring example:

(March 26, 2021)