I've had a "behavior" with my Powerwalls recently - and today after a very helpful chat session with an excellent Tesla support representative I now fully understand what was/is going on and how to work around it.
Problem/Behavior Statement: My system was not fully charging my Powerwalls on a daily basis - it was cutting "off" my battery charging and leaving the Powerwall system @ 70-85% capacity even though I had plenty of solar production to "fill up" the batteries. This was frustrating me - because we have a lot of outages in our area and I want my batteries to be top capacity so that I have plenty of power for our outages.
My Settings: Time based Controls - 50% backup capacity - w/PG&E EV-A rate schedule "entered" in the system with full off-peak, mid-peak, peak TOU rate windows entered for both week days - and weekends and the two "seasons".
what I found out…
with "Time Based controls" the powerwalls develop a history/prediction of how much power is going to be used during "peak" - during the off-peak/mid-peak rate period the Powerwall software will endeavor to optimize to only charge the Powerwall system enough above my 50% setting to make it through the peak period and "land" back at 50% capacity as it "exits" the peak power TOU rate time window. The "excess" solar produced during the mid-peak TOU-rate-time-window will be pushed to grid for NEM credits rather than used to top-off the batteries.
solution to this "problem/behavior" - in working with the Tesla phone support representative - we decide to "lie" to the Powerwalls about the TOU rate period and I removed the "mid-peak" TOU-time-windows and now my TOU schedule only contains "off-peak" and "peak" TOU-rate-time windows. In implementing this "work around" I have now seen an immediate change in behavior and the Powerwall system now uses as much "off-peak/mid-peak" solar production as it can to fill the batteries (my goal) - rather than "stopping" at the predicted capacity required to provide sufficient power for the predicted "peak" consumption time-window on the same day.
now that I understand the problem I can see why/how the Powerwall does this - but this behavior is not my preference as I have the powerwalls for backup given numerous outages in our area - but I also like to use the Powerwalls to "defend" my home and NEM bill against PG&E "peak" rate periods with my own solar and battery power.
I want to use my power to defend again "peak" rates, but not be forced to then live overnight at what ever "min" % I've selected - charge to 100% every day - and use what you need to for peak - but most of the time I want as much power as I can have for overnight - not 50%+peak-usage charging target - and always 50% overnight…
the solution of excluding "mid-peak" from the rate-schedule is an acceptable work around in my opinion - but less than ideal.
Problem: why isn't my powerwall filling up everyday when there is plenty of off-peak/mid-peak solar to provide sufficent power to top-off the batteries?
Reason: the powerall is trying to only harvest "enough" solar power from mid-peak to "meet" predicted consumption for peak on that date/day-of-week- and sell the "excess" back to grid at mid-peak rates
Solution: adjust your powerwall rate schedule mid-peak TOU time windows to reflect your personal preference about when you wouldn't mind selling mid-peak solar power to grid rather than using that power to charge your batteries.
so kudos to Tesla for coming up with this really clever behavior - but alas it's not my perference as to how it shoudl behave.
mostly I don't like "exiting" the peak rate period (9 pm most days) at 50% battery - I'd rather "exit" the peak rate period time-window with as much power for overnight for an outage - rather than the target "minimum backup" amount
also now that I understand this - I'm comfortable adjusting the minimum backup lower - 25% - because I know on most nights 25-30% will cover my peak usage window - but if I let Tesal manage it - it would only ever charge my batteries enough to cover peak time window and land back at 25% - which isn't very outage friendly…
I share this in the spirit of what I learned today- apologies if everyone else already understood this - but you learn something new every day - and this was my item for today.
Problem/Behavior Statement: My system was not fully charging my Powerwalls on a daily basis - it was cutting "off" my battery charging and leaving the Powerwall system @ 70-85% capacity even though I had plenty of solar production to "fill up" the batteries. This was frustrating me - because we have a lot of outages in our area and I want my batteries to be top capacity so that I have plenty of power for our outages.
My Settings: Time based Controls - 50% backup capacity - w/PG&E EV-A rate schedule "entered" in the system with full off-peak, mid-peak, peak TOU rate windows entered for both week days - and weekends and the two "seasons".
what I found out…
with "Time Based controls" the powerwalls develop a history/prediction of how much power is going to be used during "peak" - during the off-peak/mid-peak rate period the Powerwall software will endeavor to optimize to only charge the Powerwall system enough above my 50% setting to make it through the peak period and "land" back at 50% capacity as it "exits" the peak power TOU rate time window. The "excess" solar produced during the mid-peak TOU-rate-time-window will be pushed to grid for NEM credits rather than used to top-off the batteries.
solution to this "problem/behavior" - in working with the Tesla phone support representative - we decide to "lie" to the Powerwalls about the TOU rate period and I removed the "mid-peak" TOU-time-windows and now my TOU schedule only contains "off-peak" and "peak" TOU-rate-time windows. In implementing this "work around" I have now seen an immediate change in behavior and the Powerwall system now uses as much "off-peak/mid-peak" solar production as it can to fill the batteries (my goal) - rather than "stopping" at the predicted capacity required to provide sufficient power for the predicted "peak" consumption time-window on the same day.
now that I understand the problem I can see why/how the Powerwall does this - but this behavior is not my preference as I have the powerwalls for backup given numerous outages in our area - but I also like to use the Powerwalls to "defend" my home and NEM bill against PG&E "peak" rate periods with my own solar and battery power.
I want to use my power to defend again "peak" rates, but not be forced to then live overnight at what ever "min" % I've selected - charge to 100% every day - and use what you need to for peak - but most of the time I want as much power as I can have for overnight - not 50%+peak-usage charging target - and always 50% overnight…
the solution of excluding "mid-peak" from the rate-schedule is an acceptable work around in my opinion - but less than ideal.
Problem: why isn't my powerwall filling up everyday when there is plenty of off-peak/mid-peak solar to provide sufficent power to top-off the batteries?
Reason: the powerall is trying to only harvest "enough" solar power from mid-peak to "meet" predicted consumption for peak on that date/day-of-week- and sell the "excess" back to grid at mid-peak rates
Solution: adjust your powerwall rate schedule mid-peak TOU time windows to reflect your personal preference about when you wouldn't mind selling mid-peak solar power to grid rather than using that power to charge your batteries.
- I understand what the Powerwall is doing now.
- I can see that someone might want it to behave that way and it's quite clever
- But it's not my personal perference for how it should behave - so for now I've removed my mid-peak TOU-time-windows
so kudos to Tesla for coming up with this really clever behavior - but alas it's not my perference as to how it shoudl behave.
mostly I don't like "exiting" the peak rate period (9 pm most days) at 50% battery - I'd rather "exit" the peak rate period time-window with as much power for overnight for an outage - rather than the target "minimum backup" amount
also now that I understand this - I'm comfortable adjusting the minimum backup lower - 25% - because I know on most nights 25-30% will cover my peak usage window - but if I let Tesal manage it - it would only ever charge my batteries enough to cover peak time window and land back at 25% - which isn't very outage friendly…
I share this in the spirit of what I learned today- apologies if everyone else already understood this - but you learn something new every day - and this was my item for today.
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