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Time-based Control: Why is Powerwall used as source when solar production is adequate

Time-based Control: Why is Powerwall used as source when solar production is adequate

New Powerwall 2 owner here. System was turned on a couple of days ago. Time-based (cost savings) option was set with peak time from 4pm to 9pm as this is what my installer recommended.

During the day yesterday the PW reached 100% charge. When I checked the app yesterday at 4:10pm, it was showing solar production at 4.2kW and house consumption of 0.5kW. However, instead of the house being powered by solar, the PW was being discharged to power the house, and 100% of the solar production was being fed to the grid.

Is this expected behavior? I would have thought that the PW would be left in Standby, and solar would continue to feed the house as it had all day.

TeslaTap.com | 25. maaliskuu 2020

It makes sense to me, but it can be confusing. Ok, the solar has to go somewhere. The Powerwall is 100%, so can't go there so better directed to the grid. 100% Charge on the Powerwall is not ideal for longevity, so it would be nice to draw that down as well, so use that to power the house and bring it down. I'm guessing now but at some point, perhaps at 95 or 90% Powerwall level, the system might switch from Powerwall -> House to Solar -> Grid & House.

d60402 | 25. maaliskuu 2020

@TeslaTap.com, Thanks for the response. I agree 100% that the solar needs to go somewhere. And since I don't know otherwise, I'll give you the benefit of the doubt on your statement that 100% charge on the PW is not ideal for longevity. But of course the sun will go down. And so the PW won't stay at 100% overnight. My argument is that it is better to put the free solar into my house when it's available instead of "giving it" to the utility company.

bp | 26. maaliskuu 2020

It appears the Gateway has some functions that are implemented with a timeout (up to 5 minutes?), which can cause the system to operate in a mode that doesn't always make sense for brief periods.

If the PWs are fully charged with solar power available, and the PWs are being used to provide power to the house, wait for a few minutes and see if this continues.

It's possible this mode might change after a few minutes - and then shift to using only solar power for the house and excess sent to the grid.

d60402 | 26. maaliskuu 2020

@bp, thanks for the response. I checked periodically yesterday after 4pm, but the PW continued to power the house, and all solar being fed to the grid. At 7pm, around sunset, it was down to 92% charge.

At 9pm (end of the time-based peak period), it had 86% charge, but then it switched to the grid to power the house. Very weird.

This morning I've switched to Self-Powered, and so far that is looking good: zero grid consumption, PW powering the house, and solar charging the PW, already up to 80% at 10am.