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Powerwall charge/discharge pattern
- Thread starter maffiou
- Start date
You should show us your intraday chart and explain what you think is good or bad about it. I'll go first.
Since late February, I've finally had enough solar generation to make it through not only the Peak period, but the entire Part-Peak and Peak period (3pm-midnight) on battery. My Powerwalls have actually reached 100% several times in the past 2 weeks. My "Solar Winter" appears to be just about over.
This is a different pattern for me because I was kicked out of the PG&E EV-A rate in November that had Part-Peak from 7am-2pm to the EV2-A rate which remains Off-Peak until 3pm. That really kills the solar NEM credits, but makes the Powerwall store ALL the solar energy until full, or 3pm, whichever comes first. When there was solar generation during Part-Peak, the Powerwalls would tend to only charge up to the point that they thought there was enough stored energy to make it through the Peak and let the rest go to the grid for NEM credit. They were frequently under-charged. While the utility credits suck on the new rate schedule, it makes it much clearer what the Powerwalls should do.
Since late February, I've finally had enough solar generation to make it through not only the Peak period, but the entire Part-Peak and Peak period (3pm-midnight) on battery. My Powerwalls have actually reached 100% several times in the past 2 weeks. My "Solar Winter" appears to be just about over.
This is a different pattern for me because I was kicked out of the PG&E EV-A rate in November that had Part-Peak from 7am-2pm to the EV2-A rate which remains Off-Peak until 3pm. That really kills the solar NEM credits, but makes the Powerwall store ALL the solar energy until full, or 3pm, whichever comes first. When there was solar generation during Part-Peak, the Powerwalls would tend to only charge up to the point that they thought there was enough stored energy to make it through the Peak and let the rest go to the grid for NEM credit. They were frequently under-charged. While the utility credits suck on the new rate schedule, it makes it much clearer what the Powerwalls should do.
What version of SW is running on your PW? I can easilly reach 100% of charge, but usually my powerwall stop charging before reaching that level and the rest is sent to the grid (I have 2PW and generate about 60kwh/day at the moment)
I understand the rational for doing this on Fridays, as the PW will be refilled at off peak time the next day. The rest of the week, not so much... Today it stopped charging once it reached 72%, which is probably enough to keep me going until the next day, but still I'd rather have a full charge...
Now, today, during peak hours, the PW seems to just be content to supply the base load but none of the other charges... This defeats the purpose of the optimization really... And obviously it's the day that my wife decides to run as much laundry through the dryer as physically possible...
I understand the rational for doing this on Fridays, as the PW will be refilled at off peak time the next day. The rest of the week, not so much... Today it stopped charging once it reached 72%, which is probably enough to keep me going until the next day, but still I'd rather have a full charge...
Now, today, during peak hours, the PW seems to just be content to supply the base load but none of the other charges... This defeats the purpose of the optimization really... And obviously it's the day that my wife decides to run as much laundry through the dryer as physically possible...
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I am on 1.45.0. However, the difference in behavior is due to the difference in the schedule. You appear to be on a rate schedule very much like the EV-A schedule I used to be on. You are also seeing the same behavior I used to see where the Powerwalls would stop charging before full during the Part-Peak period. My feeling is that the system is trying to be too smart for its own good.
With so much surplus solar in your situation, I would like to see the Powerwalls go into a mode mid-morning where they just charged at a fixed rate so that they would hit 100% just before the start of the Peak period. It's very simple math. It could also charge only from Surplus Solar at the beginning of the solar day, letting the solar offset household use until the solar exceeded consumption, at which point it would start charging the batteries.
With so much surplus solar in your situation, I would like to see the Powerwalls go into a mode mid-morning where they just charged at a fixed rate so that they would hit 100% just before the start of the Peak period. It's very simple math. It could also charge only from Surplus Solar at the beginning of the solar day, letting the solar offset household use until the solar exceeded consumption, at which point it would start charging the batteries.
What version of SW is running on your PW? I can easilly reach 100% of charge, but usually my powerwall stop charging before reaching that level and the rest is sent to the grid (I have 2PW and generate about 60kwh/day at the moment)
I understand the rational for doing this on Fridays, as the PW will be refilled at off peak time the next day. The rest of the week, not so much... Today it stopped charging once it reached 72%, which is probably enough to keep me going until the next day, but still I'd rather have a full charge...
Now, today, during peak hours, the PW seems to just be content to supply the base load but none of the other charges... This defeats the purpose of the optimization really... And obviously it's the day that my wife decides to run as much laundry through the dryer as physically possible...
If you want to get to 100%, eliminate your part-peak and extend your off-peak all the way to 2pm. Once the PW is full, excess solar will go to the grid. Part-peak doesn't work very well in the PW. This is what I do, and I'm always at 100% by the time the peak starts.
I just got my Powerwalls in February. I'm on 1.44.4 and Advanced Cost Saving mode. I'm on EV-A with peak, partial-peak, and off peak. In the morning (off peak and partial peak) the Powerwalls charge from solar until they are 100% full. Then they discharge during peak to zero out the load from my house, so all the solar generation is exported to the grid during peak. After the sun goes down the powerwalls continue to export until 9pm when peak time ends.
Yes, I'm on the same tarif and this is how it used to work for me, with a small difference on Friday's where the powerwall would stop charging early and carry on supplying the house until 11pm (all of part peak) as there is ample off-peak time to recharge on Saturday. That pattern made sense to me...
You can see that things have changed in here:
http://home.maffiou.com:9000/d/RSDbqvRRz/powerwall?orgId=1&from=1583043782438&to=1583512213521
Full charge on Sunday and Monday, but no charge at all on Tuesday (PW at 68%), then charge to 79% and 73% on Wednesday and Thursday respectively... Why did it decide to do forgo the charge?
On top of that, on Thursday afternoon, at the start of the peak period (for the first hour), the PW decided to supply 600w, regardless of the house usage:
http://home.maffiou.com:9000/d/RSDbqvRRz/powerwall?orgId=1&from=1583442098040&to=1583458806410
Things seem to work as expected after that...
I'm wondering if the PW has learnt enough about my usage pattern and is trying to be clever about it? A bit too clever in my opinion: It's all very well trying to minimize part peak charging, but it's all moot if we run out of power during peak or don't supply the house for some mysterious reason...
I might go and set off peak for part peak period and prevent it from being too clever...
I don't see any problem setting the morning to mid-day Part-Peak to Off-Peak in the app. I would leave the evening Part-Peak alone though.
I wish we had more control. What I really want is to charge the Powerwall to 100% using solar during off peak and part peak, and discharge more than my home usage to the grid during peak, down to 25% or so unless there's a storm brewing. In other words CPUC "no grid charging" mode. Since I am required to have the net generation output meter (NGOM) PG&E should be able to know that I am only exporting my solar production. This would give me the most $ benefit.