System not honoring Powerwall reserve setting?

[ScottRiqui]

Right now, I'm in the "peak" part of the day, pricing-wise. The house is drawing 2.2 kW, with 1.6 kW coming from the solar (it's raining and very cloudy out), and 0.6 kW coming from the Powerwalls. The problem is, I'm in "Advanced / Balanced" mode, with "Reserve for Power Outages" set to 25%, and the Powerwalls are already down to 22%.

Under these circumstances, shouldn't the house be getting power from Solar + Grid, rather than Solar + Powerwalls?

 

[skepticcyclist]

Right now, I'm in the "peak" part of the day, pricing-wise. The house is drawing 2.2 kW, with 1.6 kW coming from the solar (it's raining and very cloudy out), and 0.6 kW coming from the Powerwalls. The problem is, I'm in "Advanced / Balanced" mode, with "Reserve for Power Outages" set to 25%, and the Powerwalls are already down to 22%.

Under these circumstances, shouldn't the house be getting power from Solar + Grid, rather than Solar + Powerwalls?

No. During peak the battery solely supplies the house. If you want solar to go to the house either set it to backup only or change it from peak to midpeak in Balanced

Powerwall Modes of Operation With Solar

Powerwall is customizable and can operate in a number of modes controlled directly from your Tesla mobile app. This article describes the operation of Powerwall in these modes. If your sys...

swellenergy.zendesk.com

 

[ScottRiqui]

I may not have been clear in my post - solar *is* going to the house just fine. The problem is that the Powerwalls are *also* powering the house, even though I'm already below the "Reserve for Power Outages" setting on the Powerwalls (the setting is 25% and the Powerwalls are at 22%).

I thought the whole point of the "Reserve for Power Outages" was to not let the Powerwalls get below X%, so I'll have a reserve if the grid goes down.

With a house consumption of 2.2 kW, I'm getting 1.6 kW from the solar and 0.6 kW from the Powerwalls. But since I'm already below the reserve threshold for the Powerwalls, I was expecting to draw 1.6 kW from the solar and 0.6 kW from the grid.

What's the point in having a "reserve" setting on the Powerwalls if the system will continue to drain the Powerwalls down below their reserve, even with grid power available?

 

[getakey]

I use Cost Saving mode and I've never seen PWs go below reserve

 

[skepticcyclist]

I may not have been clear in my post - solar *is* going to the house just fine. The problem is that the Powerwalls are *also* powering the house, even though I'm already below the "Reserve for Power Outages" setting on the Powerwalls (the setting is 25% and the Powerwalls are at 22%).

I thought the whole point of the "Reserve for Power Outages" was to not let the Powerwalls get below X%, so I'll have a reserve if the grid goes down.

With a house consumption of 2.2 kW, I'm getting 1.6 kW from the solar and 0.6 kW from the Powerwalls. But since I'm already below the reserve threshold for the Powerwalls, I was expecting to draw 1.6 kW from the solar and 0.6 kW from the grid.

What's the point in having a "reserve" setting on the Powerwalls if the system will continue to drain the Powerwalls down below their reserve, even with grid power available?

Technically it should not discharge below the reserve. Change it to cost savings. Balanced sometimes does weird things as it learns your system and usage, which takes a while to adjust to new situations. Or if you just changed your reserve level it may tike a bit to adjust.

Plus remember that the percentage displayed is not 100% accurate and if you log into TEG and view the battery level through the IP address it will most likely show it still over 25%

 

[ScottRiqui]

Ah - this is only my fourth day since PTO, so I could definitely still be in a “learning” phase.
I can’t experiment any more today, because the rain has stopped and the solar is now producing enough to both power the house and start recharging the Powerwalls. I’ll keep an eye on it the next time I’m in the same situation.

 

[jjrandorin]

Ah - this is only my fourth day since PTO, so I could definitely still be in a “learning” phase.
I can’t experiment any more today, because the rain has stopped and the solar is now producing enough to both power the house and start recharging the Powerwalls. I’ll keep an eye on it the next time I’m in the same situation.

The percentages you see in the app are not the actual percentages of the battery. Its confusing, but 0% in our display is not 0% of the battery, and 100% of the display isnt 100% of the battery. There is a thread here somewhere that has a chart.

Anyway, with some of the recent updates, this seems to have become more visible in the app (my opinion). I use self powered mode and change my reserve percentage frequently, manually based on what the next days weather is going to be, etc (I still enjoy looking at it manually like this, over a year after installation of the powerwalls).

I have noticed that, with the latest updates, There are more instances of "I set the reserve to 30% but the battery stopped discharging at 28%". Its my guess that this reserve percentage is just becoming more visible in the app, or some formula was changed to display it.

I will see if I can find one of the threads that talks about the "checking battery via its direct web interface doesnt match app" threads and link it here if I find one.

EDIT: Here is one thread. The thread link is to the specific post from @power.saver with the chart, but you can read the thread, this one is only 2 pages long. There are a few others around too, but the chart in this post shows the difference

Why would PW send power to the grid?

The App shows a lower % than the API. It follows the formula in this chart:

teslamotorsclub.com

 

[h2ofun]

The percentages you see in the app are not the actual percentages of the battery. Its confusing, but 0% in our display is not 0% of the battery, and 100% of the display isnt 100% of the battery. There is a thread here somewhere that has a chart.

Anyway, with some of the recent updates, this seems to have become more visible in the app (my opinion). I use self powered mode and change my reserve percentage frequently, manually based on what the next days weather is going to be, etc (I still enjoy looking at it manually like this, over a year after installation of the powerwalls).

I have noticed that, with the latest updates, There are more instances of "I set the reserve to 30% but the battery stopped discharging at 28%". Its my guess that this reserve percentage is just becoming more visible in the app, or some formula was changed to display it.

I will see if I can find one of the threads that talks about the "checking battery via its direct web interface doesnt match app" threads and link it here if I find one.

One plus about having a few batteries, and not running heating or AC at the moment. Even though though seem to be used most of the time so I am off grid a lot, their percentage do not get below 75%, even though I have them set at 10%. I hit 80kwh yesterday on my solar, so when there is sun life is fun. But in winter, ...

 

[eml2]

I am using Balanced mode. I also notice that the Powerwall will not stop at reserve when it is in Peak. I have my Powerwall for more than 3 years. So, I can't give it the "still learning" excuse.

BTW, the formula to convert between the SoC % on the App and Web UI:

(App % x 0.95) + 5 = Web %

 

[bob_p]

Our PowerWalls will periodically dip a few % below the reserve power % with Cost-Saving.

It hasn't been enough to worry about.

 

[ScottRiqui]

Our PowerWalls will periodically dip a few % below the reserve power % with Cost-Saving.

It hasn't been enough to worry about.

We've had a couple of sunny days, so the Powerwalls haven't gotten down low enough to experiment further. But the other day when they were dropping down below the 25% threshold, they did stop discharging around 22-23%, so it's probably just a slight discrepancy between what the Powerwalls think their state of charge is and what the app's reporting.

 

[bob_p]

The app and web interface report different charge level numbers. It's possible that might account for the discrepancy.