I never touched my powerwall settings. I just leave on self powered! One reason I try to suggest to folks, put on as MUCH solar as your roof will handle and you can get approved. Technically my batteries have zero value to cost savings for me.
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New Powerwall Advanced Options [Toggles for charging from and discharging to grid from powerwalls]
- Thread starter dailo
- Start date
I use Home Assistant to do most of the automation, so at peak hour it toggles export to Everything and then once it drops below 60% it switches back to solar. Maybe one day I'll turn it into a proper add on but for now I just call a simple python script to toggle the setting.
Just found out about this yesterday from brother. Here's datapoint:
SDGE; Telsa installed PW+solar. Owned. on EV rate. No SGIP
Able to fully enable export everything and grid charging.
So Peak hours - PW2 discharges steadily for about three hours to reserve set at 20% (still want backup just in case)
PW2 starts charging at MN along with EVs to capacity at super off peak rates
AM: Solar - production fully goes to house/grid since PW2 is fully charged by AM.
ie: full, max arbitrage achieved
SDGE; Telsa installed PW+solar. Owned. on EV rate. No SGIP
Able to fully enable export everything and grid charging.
So Peak hours - PW2 discharges steadily for about three hours to reserve set at 20% (still want backup just in case)
PW2 starts charging at MN along with EVs to capacity at super off peak rates
AM: Solar - production fully goes to house/grid since PW2 is fully charged by AM.
ie: full, max arbitrage achieved
I'm still trying to get my head around export strategy. Your approach sounds easy, and if I'm seeing SDGE EV rate correctly, your super-off-peak $0.10/kWh is enviable. Here in PG&E land we pay $0.25 off peak to charge the car.
First question is what is your situation on the income tax credit for the PW. Grid charging might be a concern for folks who took ITC.
But check me on this regarding maximizing export credits:
My understanding of Non-Bypassible-Charges (NBCs) is that in effect they are a small tax on exported power, roughly 3 cents per kWh, or ~7% reduction in your peak rate credit. Would this mean that re-importing power after the battery is down to the reserve level entails a slight decrease in arbitrage value?
In your case, after PW reaches your reserve during peak, any non-solar power you use before peak ends would be imported. The import price is full retail, including NBCs, but the export is less the NBCs.
Maybe I've got this wrong? Or maybe the $ are insignificant, or I'm just overthinking this.
Might the net credit be a bit higher if you slowed the export so that PW could keep powering the house till the end of peak? Or does solar still have enough to power the house till 9pm?
Since the export rate is not adjustable, maybe one could delay the start of PW export so it ends around 9 when peak ends? However, the export is done at a constant grid power, causing the PW discharge rate to vary with changing solar contribution and house draw, making estimation imprecise.
Thanks,
SW
The Tesla app supports setting different Buy and Sell prices. Has anyone on NEM2 tried setting the Sell price slightly below the Buy price (maybe 3-4 cents) to see if it moderates the "Export Everything" behavior? If the algorithm is clever enough it will forego some selling to avoid future buying and attempt to give a "soft landing" at the Reserve level at the end of Pak.
Of course, since from my point of view it took Tesla almost 4 years to introduce Export Everything, it's possible the algorithm isn't clever enough yet, and it will take another year or two before that works.
Cheers, Wayne
Of course, since from my point of view it took Tesla almost 4 years to introduce Export Everything, it's possible the algorithm isn't clever enough yet, and it will take another year or two before that works.
Cheers, Wayne
So for you the benefit of PWs is mostly backup, especially during extended outages when your solar can help cool or heat your home, am I right? Are you on well water too, another huge potential issue during outages.
In my case, limited roof real estate and significant afternoon shading from neighbors' trees makes adding solar more difficult. Now that we are charging the car at home, the economics loom large. For us, the PW gives us substantial economic leverage on our solar by allowing us to import only off-peak, EV priced power. The new capability to time shift the export of excess summer solar production into peak price periods adds even more leverage to our solar.
However, I lucked out and SGIP paid for our PW, making the ROI essentially infinite, and even eliminating the need for income tax credit entanglement. So I can not comment on how PW might pencil out for other situations. Heck, it is so complicated that I have not yet managed to estimate what my future true-up's may be! I'll get there, but with abstruse tariffs, variable shade and fog, EV milage, un-documented PW behavior, no Game of Thrones replacement on our plasma TV (600+W), and a longing for heat pumps for house, hot water and clothes dryer, it is hard to know what our electricity needs are, much less the cost.
Bottom line: every situation is different. Blessed be they with abundant solar production and backup to boot!
SW
I am on NEM1, but set lower sell price to see what happens. It is early on in this experiment, but it appears that export continued full bore down to the backup reserve setting well before the end of peak. Sigh.
The export here stopped around 7:30 when the PW got down to my 20% reserve setting. At that point, I started importing peak price power, something I have studiously avoided since PW day one.
aesculus
Still Trying to Figure This All Out
charlesj
Active Member
At least on NEM1, with no NBC's, there's no net harm right? Yes you imported during peak, but you exported more during peak, so whether you self-consumed from the Powerwall directly or exported it, isn't it the same result?
Now NEM2, different story with NBC's....
No well water.
Since I a 22kw whole house generator, it really is a toy. We get so few power outages that I just tell folks get the most solar first.
And if I were going to buy a bunch of batteries now, I would not. Would buy the Ford F-150 now since one can get batteries and a car for about the same price.
Between the the date and the word Day is a circle. Click that to color in the sources/destinations of the power. The dot below the power tower icon means this display is showing the grid power, with colors representing house, solar and battery contributions.
SW
charlesj
Active Member
Right, same result on NEM1.
I do have another issue, though. PG&E says my export limit is ~20kWh/day this month, but my solar is producing 30 kWh. So, to minimize export, I am self consuming as much as I can.
I expect that if I get PG&E to fix their estimation, they will force me into NEM2. I am suspecting that if that happens, the larger export limit may let me increase my exports and earn me more credit than the NBC's will cost me. Now that I'm getting clergies on how PW behaves, I've got to plug in some numbers to see how various strategies and NEM2 will affect my true-up. I expect there is a large spreadsheet in my near future.
For now I am putting PW in self consumption mode in the morning so that it uses solar rather than import to run the house, then switching to Time Based so it does export during peak. I'm also charging the car once the PW reaches 100% and starts to export the solar, thus reducing the export as much as I can till peak starts at 4 pm. During peak I set Export Everything as needed to get down to my 20% reserve at 9pm when peak ends. Anyway, that is my present best guess at how to get optimum credit.
Yeah, that and touching the chart to get exact readouts of the values and times is pretty cool. I'm pretty happy with the new app design.
It would be nice if changing the date had a calendar option instead of only day by day. Plus I'm still not getting the $ impact cards, meaning I've got to do the arithmetic myself, but I think that is yet another glitch in my account set-up on Tesla's servers.
Doing the circle does not seem to show what you show, I get basically solar, see no batteries. I go not use much grid so do not expect to see much if any blue
To be clear, the new(ish) display still doesn't have as much info as the old display. If we call the 4 numbers G(rid), H(ouse), S(olar), and P(owerwall), the old display let you see all 4 at once. But the new display doesn't show all the info, which is a regression IMO.
If you call G and H positive when the house is consuming, and S and P positive when they are discharging to the local microgrid, then the microgrid balance says that H = G + S + P. Looking at the example you posted, when G is positive you have G = H (blue) because all the solar is going into the Powerwall (S + P = 0). But the display doesn't tell you the value of |S| = |P|. And when G is negative, it's telling you some breakdown of S and P that match that G, but it doesn't tell you H, and doesn't tell you how it is assigning S and P to G vs H.
Cheers, Wayne
I wonder if you are just looking at the grid data, where you would mostly be exporting solar. The grid data will show yellow for solar, blue for house and green for battery, but no grey because that is what those others are contributing to. With the circle turned off, it would all be grey.
Here is what I'd expect you would see. If you slide the display over to see the full day of yesterday's data, and select the house icon, you should see solar as the source during the day, and battery from sun down till sun up, assuming you use no grid power at all. All of it will be above the centerline, because house consumption is shown as positive numbers. Likewise solar production and grid import. Only battery charging and grid export are negative.
If you select the battery icon, you'll see solar charging and house discharging in daylight and dark hours respectively.
If you select the solar icon, you'll see it split between solar and house.
The details will depend on your settings, self consumption, backup reserve, etc.
I hope I got this right....
SW
charlesj
Active Member
Select one then repeat tapping that circle. Seems to add more but not all, not the full days worth to the time you check at least not for me, not yet. More research and experimenting for me.