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System is switching from grid to PowerWalls during free off-peak period.

I have a "free nights" (8pm-5am) plan, so I'm trying to get my system to only use the grid to power my house during those hours. For the past few weeks I've been manually switching to "backup only" at 8pm and then manually switching to "Advanced/Balanced" at 5am. That works, but I was hoping to get the system to do it automatically, so I've been leaving it on "Advanced / Cost Saving" for the past few days.

The system has been correctly switching the Powerwalls off at 8pm and drawing from the grid instead, but it's been switching from the grid back to the Powerwalls around 2:30-3:00am, when I still have 2-2.5 hours of free grid power left. Any idea why it's doing this? I've correctly defined the "peak" and "off-peak" hours in the app, and my plan has no "shoulder" times - just "peak" from 5a-8p and "off-peak" from 8p-5a. I've included pictures of the Powerwall usage for yesterday and today.
 

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I'm guessing here but maybe the system is seeing a large differential between the SoC and reserve setting and trying to use the charge.
You could try raising your reserve to see what it does.
That makes sense - I'll give it a try. Of course, I have an unrelated issue where the system isn't honoring my reserve setting and will happily blow past it (and not just by a little bit), but maybe the most recent software update will make a difference. I'm on 20.49.0 which isn't the absolute newest, but it's newer than what I had when the system was installed in March.
 
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That makes sense - I'll give it a try. Of course, I have an unrelated issue where the system isn't honoring my reserve setting and will happily blow past it (and not just by a little bit), but maybe the most recent software update will make a difference. I'm on 20.49.0 which isn't the absolute newest, but it's newer than what I had when the system was installed in March.
Maybe the two are related. I use Advanced - Cost Saving with Peak set to 4-9pm and Off-Peak set to 9pm-4pm, and my reserve set to 50%. I never blow past my reserve and never discharge during Off-Peak, even if I've got 75% SoC at 9pm. It sounds like your system may have a problem.
 
I would give it a few days to "learn" your new settings and history. Maybe a week.
I've seen this multiple times, but it should not be necessary to "learn" especially without any understanding of what the inputs parameters are.

Just give us explicit control for the Powerwall charge (100% from solar to PW, 100% from solar to house then PW), discharge (100% from PW to house, 100% from solar to house then PW, standby).

The Tesla app shows an incorrect understanding of Peak for me (reports grid imports when none happen during the Peak time I set or from the preset PG&E E-TOU-C) so I don't trust how it is learning, nor why it should even need to learn.
 
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I've seen this multiple times, but it should not be necessary to "learn" especially without any understanding of what the inputs parameters are.

Just give us explicit control for the Powerwall charge (100% from solar to PW, 100% from solar to house then PW), discharge (100% from PW to house, 100% from solar to house then PW, standby).

The Tesla app shows an incorrect understanding of Peak for me (reports grid imports when none happen during the Peak time I set or from the preset PG&E E-TOU-C) so I don't trust how it is learning, nor why it should even need to learn.
I agree. The one "smart" feature I'd like to be able to combine with this is to have the system recognize if it won't be able to fully recharge the Powerwalls before the next peak period (if solar is being prioritized to the house) unless it prioritizes solar to the Powerwalls.

However, if they could come up with a true Cost Saving mode that takes NBCs, cycle life, actual TOU rates, excess generation compensation rate, etc. into account I'd be all for that.
 
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MorrisonHiker

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Mar 8, 2015
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The Tesla app shows an incorrect understanding of Peak for me (reports grid imports when none happen during the Peak time I set or from the preset PG&E E-TOU-C) so I don't trust how it is learning, nor why it should even need to learn.
It sounds like your CTs aren't configured correctly. You should open a service ticket to get that resolved so that the reporting is correct.

As for learning, the Powerwalls can look for patterns and know when they can be used. For our system, our Powerwalls know that they can power the house to help charge cars during off-peak, right before sunrise. They throttle a combination of grid power and Powerwall power back and forth so that they can get as close as possible to the reserve before they start charging again. This is the desired behavior for our system as we try to minimize our grid usage.
 

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