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Dumping Excess Power During Peak Period

aesculus

Still Trying to Figure This All Out
May 31, 2015
4,433
2,511
Northern California
I was alarmed and called Tesla support and they told me that is the way cost savings mode works. It runs a rolling week load analysis and figures out how much power it thinks it needs for peak consumption plus your stated reserve and that is the SoC it uses to determine when to send power to the grid.
Just a point I mentioned in another thread that was backed up by others observations for Cost Base mode: It appear that if you have a dramatically different TOU rate on Sat/Sun (like EVA on PG&E) that the PW can charge to a much lower value on Friday and even perhaps Thursday knowing that they won't need much energy to bank until the lower price on the weekend.

In my case during the weekdays it will generally try to charge to 100% during the day and then dump excess solar after that. On Fridays it will only charge to 75% and then send as much solar as it can, even before peak at 3pm. Then when partial peak arrives at 9pm Friday it's down to about 55% (50% reserve) in my case and the PW switch back to grid mode.
 

CrazyRabbit

Member
Apr 21, 2020
410
123
Fort Worth TX
i live in Texas and we are not yet allowed to export to the grid. The option to export only appears in the app if your jurisdiction allows export. But it would be in everyone's interest to allow exporting, controlled by ERCOT or your local jurisdiction, before they start rolling blackouts... i would opt in for something like that, subject to my reserve limits.
 

aesculus

Still Trying to Figure This All Out
May 31, 2015
4,433
2,511
Northern California
In my case during the weekdays it will generally try to charge to 100% during the day and then dump excess solar after that. On Fridays it will only charge to 75% and then send as much solar as it can, even before peak at 3pm. Then when partial peak arrives at 9pm Friday it's down to about 55% (50% reserve) in my case and the PW switch back to grid mode.
Just a point from yesterday. The algorithm went over the line a bit. Peak ends at 9PM and at 8:45PM we hit the reserve so we ended up paying a bit more for power than we should have. Not sure what drove the use but Tesla is kind of cutting it a bit too close perhaps. Maybe they should aim to leave 10% of a buffer instead of just a few percent.
 

bobbyclee

Member
Aug 28, 2020
10
1
Las Vegas, NV
But it doesn't even do that fully. I have had it charged to 90% and the only thing it does right at peak is to stop charging the battery and start using solar to power the home and feed the leftovers to the grid.

Sometimes for a short period of time, i.e. at low incoming solar after 5pm, it would do what I would love it to do all the time during peak, which is power home from battery and direct all solar to grid. But most of the time it doesn't, even with the battery charged to 90%.

I have 3 home batteries close to 40kWh capacity, 10kW solar panels (40x250W) via two SMA sunny boy inverters.

Hi Skryll,

Did you get your PowerWalls to do what you wanted?

I'm in the same boat (I just recently got my PowerWalls running):
During Peak, I want to send 100% of my solar to the grid, and use the PW to power my home.

Currently, on Advanced TBC - Cost Saving Mode, it still does NOT do that for me. I've set the Peak times correctly, with just a low 10% for Power Outage Reserve, but still, the PW will refuse to full power the house during Peak. Instead, it would let Solar power the house for the first part of Peak, and then later kick in to cover the shortfall from Solar. (I'm on the latest 1.48.1 firmware.)

I'm frustrated that my PW is not allowing me to send 100% of Solar to Grid during Peak.

Any suggestions, anyone?

thanks,
Bobby


IMG_4467.PNG
 

miimura

Well-Known Member
Aug 21, 2013
6,257
5,880
Los Altos, CA
Hi Skryll,

Did you get your PowerWalls to do what you wanted?

I'm in the same boat (I just recently got my PowerWalls running):
During Peak, I want to send 100% of my solar to the grid, and use the PW to power my home.

Currently, on Advanced TBC - Cost Saving Mode, it still does NOT do that for me. I've set the Peak times correctly, with just a low 10% for Power Outage Reserve, but still, the PW will refuse to full power the house during Peak. Instead, it would let Solar power the house for the first part of Peak, and then later kick in to cover the shortfall from Solar. (I'm on the latest 1.48.1 firmware.)

I'm frustrated that my PW is not allowing me to send 100% of Solar to Grid during Peak.

Any suggestions, anyone?

thanks,
Bobby
Call Tesla. That is not normal system operation during Peak with TBC-Cost Saving mode.
 

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