I might ask for more information in a few weeks.
We're still waiting for everything to be installed later this month.
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Configure Powerwalls To Ignore Solar?
- Thread starter wwhitney
- Start date
We're still waiting for everything to be installed later this month.
So I can finally follow-up on this conversation. The Gateway/PowerWalls can be configured for grid-charging in the USA even if there is existing on-site solar. I was able to grid-charge once overnight on initial commissioning under 1.35.2 region CA split-phase 120/240V 60Hz.
However, it looks like there's some sort of poison pill in the system that if it ever gets configured for solar, it is marked as solar and will no longer charge from grid when configured back to standalone-no-solar -- unless it's under Storm Watch.
It also looks like the Gateway gets confused if the site CTs show negative values, such as when solar is producing, so the PWs won't charge in that state.
If there was a way to factory-reset the Gateway and redo the initial commissioning, instead of any follow-up reconfiguration, then maybe grid-charging can be restored.
The app is also broken (as of 3.8.4) where it only offers "Backup-Mode" and doesn't show "Self-Consumption" (nor the reserve), when in standalone configuration.
If by "standalone configuration" you mean without solar, that's to be expected. "Self-consumption" only makes sense if there's solar - it means consuming your own generated power. Time-based control (i.e. "Advanced") should be available, though, but it also seems there may be some back-end configuration required to turn that on since there are other reports of it not being there initially after installation.
Thanks, you're correct that there's no self-consumption for no-solar aka standalone configuration (per the FAQs), even though the Installation Wizard shows and supports it as a specific mode.
For TBC, the claim is it will show up in the app after a few days. I haven't seen it yet, but it may be because I've been reconfiguring everyday so far. If I leave it alone and it still doesn't show up, I guess I'll poke Tesla support after.
Please keep me updated. I will not be claiming the ITC so I want to have the PW charge off the grid late at night when rates are basically free.
Unfortunately, those of us in the US who aren't claiming the ITC are still not able to charge from the grid unless there is a Storm Watch event (or if you don't have solar). Hopefully that will be allowed in the future.
@wwhitney I have a few questions:
1) The two-page summary of your proposed system hookup wrt PG&E I think is here: https://www.pge.com/pge_global/comm...Paired-Storage-Frequently-Asked-Questions.pdf
Which boxes do you fit in? (This is all for NEM paired storage which CAN export to grid, i.e. non-exclusive charging by NEM generator and what PG&E calls Direct Connect).
2) Although I started my project in 2017, I was hit by new PG&E paired storage interconnect fees effective 2019. Since you filled out all your own paperwork, I was wondering what these fees are for you, and if they are impacted by switching to “Direct Connect” rather than non-export? The relevant PG&E form is titled “Agreement for Installation or Allocation of Special Facilities for Parallel Operation of Non Utility-Owned Generation and/or Electrical Standby Service (Electric Rules 2 and 21)” and the fees are calculated in “Appendix A - Detail of Special Facilities Charges.” (whew) There is option to pay a monthly charge (forever?) or a one-time fee.
3) As to the cost benefits of grid-charging and PG&E: my understanding is that for your proposed scenario (Direct Connect), PG&E places a cap on monthly allowed export energy, based on a CSI calculator. Any NEM credits per month are capped at this value. It sounds like you can’t even roll them over for a yearly true-up. This is called Special Condition 11 on NEM Paired Storage of the PG&E NEM 1 Tariff. (There is analogous rule for NEM2). How does this impact your ROI calculation?
1) The two-page summary of your proposed system hookup wrt PG&E I think is here: https://www.pge.com/pge_global/comm...Paired-Storage-Frequently-Asked-Questions.pdf
Which boxes do you fit in? (This is all for NEM paired storage which CAN export to grid, i.e. non-exclusive charging by NEM generator and what PG&E calls Direct Connect).
2) Although I started my project in 2017, I was hit by new PG&E paired storage interconnect fees effective 2019. Since you filled out all your own paperwork, I was wondering what these fees are for you, and if they are impacted by switching to “Direct Connect” rather than non-export? The relevant PG&E form is titled “Agreement for Installation or Allocation of Special Facilities for Parallel Operation of Non Utility-Owned Generation and/or Electrical Standby Service (Electric Rules 2 and 21)” and the fees are calculated in “Appendix A - Detail of Special Facilities Charges.” (whew) There is option to pay a monthly charge (forever?) or a one-time fee.
3) As to the cost benefits of grid-charging and PG&E: my understanding is that for your proposed scenario (Direct Connect), PG&E places a cap on monthly allowed export energy, based on a CSI calculator. Any NEM credits per month are capped at this value. It sounds like you can’t even roll them over for a yearly true-up. This is called Special Condition 11 on NEM Paired Storage of the PG&E NEM 1 Tariff. (There is analogous rule for NEM2). How does this impact your ROI calculation?
I have 10kW of storage capacity (two Powerwalls) and 2.4 kW of PV. So it looks like I'm Small NEM Paired Storage, while I'm also under the NEMMT tariff because the storage capacity is more than 150% of the NEM-eligible generator's capacity.
My interconnection fee was $0 because my PV is under NEM1 and the NEM1 tariff specifies (item 11b) that the cost of adding storage is $0. The NEM2 tariff, however, has an interconnect fee for adding storage, and so PG&E tried to charge me the interconnect fee until I pointed out the wording in the NEM1 tariff.
Right, the calculation is done on a month-by-month basis to estimate what your PV system could produce. They don't want you to charge your storage from the grid during off-peak, then export it during peak, and claim it was from your PV system. So they (in theory) check that your exports for the month do not exceed your NEM-eligible renewable generator's expected production for the month.
However, at the time of my interconnection, no one I spoke with at PG&E knew whether this was ever implemented in their billing software.
I don't see anything in section 11g that suggest that, I believe the monthly export cap doesn't affect your annual true up procedure. Certainly it hasn't affected mine (other than changing the true-up date to the date of PTO on the storage and concordant switch to NEMMT).
If you haven't read the tariff itself, it is available at https://www.pge.com/tariffs/assets/pdf/tariffbook/ELEC_SCHEDS_NEM.pdf
Cheers, Wayne
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Thanks. I had gone through various parts of that huge tariff document and that was why I asked about the interconnection fee. I am on NEM1 and couldn’t find the place where it is required, except Tesla told me it was required effective Jan 2019, even on NEM1 and sent me a pre-filled PG&E form to sign with their calculation for how much I would owe (the name of the form is the long title I quoted in item 2). I asked how this was going to be billed and they said “that’s a great question.” It’s the Wild West out here...
I suspect it was not implemented at the time, however the estimated production has now been on my bill (on page 3 of the detailed bill) for the past two months:
Interesting. I just got the bill for my first annual true-up on NEMMT and the Paired Storage shown above does not appear on my bill. I get the full detail black and white bill that usually runs 10 or 11 letter size pages. Mine may be more complicated because it includes CCA calculations.
For my interconnection, I believe I only had to complete Form 79-1193 "AGREEMENT AND CUSTOMER AUTHORIZATION Net Energy Metering Interconnection For Solar And/Or Wind Electric Generating Facilities Of 30 Kilowatts Or Less Paired with Energy Storage of 10 Kilowatts Or Less" I can't find that form as a stand-alone PDF, but it is available starting on page 543 of this enormous PDF:
https://www.pge.com/tariffs/assets/pdf/adviceletter/ELEC_5185-E.pdf
Cheers, Wayne
https://www.pge.com/tariffs/assets/pdf/adviceletter/ELEC_5185-E.pdf
Cheers, Wayne
pdxgibby
Software Engineer
Excellent thread. My 2 powerwalls are being installed on June 11-12, 2019. Right around the corner...can't wait.
In Oregon, we get 1 for 1 credits for excess solar production. When combined with Time of Use rate plan, any excess solar is applied to excess on-peak consumption first, then mid-peak and lastly off-peak. Our credits reset annually at the end of March (after the cloudy / rainy winter months have hopefully used up all credits).
I was hoping to add TOU Load Shifting to my system, but based on the information in this thread, and my discussions with Tesla as well, it is not possible to configure the powerwalls to charge from the grid in the presence of a PV system (at this time). I'm told it's just a software change (which makes sense since it is possible in Austrailia) which *could* be enabled in the future for the US.
Ideally, I want:
Always charge EVs from the grid during off-peak rate schedule
Always charge Powerwalls from the grid during off-peak rate schedule
House consumes from PV system when being generated
Excess PV always goes back to the grid to earn credits
If house consumption is higher than currently producing solar, 2 cases:
1) If Powerwall capacity is > minimum %, draw from powerwalls
2) If Powerwall capacity is <= minimum %, draw from the grid
If above is not possible, I don't want to use my powerwalls for anything except for battery backup. The idea of preserving excess solar in a powerwall (which is not 100% efficient) instead of giving it back to the grid which is a lot closer to 100% efficient means that the powerwalls will end up costing me money using Tesla's TBC algorithm.
It sounds like @wwhitney has the same goals that I do...but no success so far.
Would love to hear updates if anyone figure out how to make this happen.
In Oregon, we get 1 for 1 credits for excess solar production. When combined with Time of Use rate plan, any excess solar is applied to excess on-peak consumption first, then mid-peak and lastly off-peak. Our credits reset annually at the end of March (after the cloudy / rainy winter months have hopefully used up all credits).
I was hoping to add TOU Load Shifting to my system, but based on the information in this thread, and my discussions with Tesla as well, it is not possible to configure the powerwalls to charge from the grid in the presence of a PV system (at this time). I'm told it's just a software change (which makes sense since it is possible in Austrailia) which *could* be enabled in the future for the US.
Ideally, I want:
Always charge EVs from the grid during off-peak rate schedule
Always charge Powerwalls from the grid during off-peak rate schedule
House consumes from PV system when being generated
Excess PV always goes back to the grid to earn credits
If house consumption is higher than currently producing solar, 2 cases:
1) If Powerwall capacity is > minimum %, draw from powerwalls
2) If Powerwall capacity is <= minimum %, draw from the grid
If above is not possible, I don't want to use my powerwalls for anything except for battery backup. The idea of preserving excess solar in a powerwall (which is not 100% efficient) instead of giving it back to the grid which is a lot closer to 100% efficient means that the powerwalls will end up costing me money using Tesla's TBC algorithm.
It sounds like @wwhitney has the same goals that I do...but no success so far.
Would love to hear updates if anyone figure out how to make this happen.
SoundDaTrumpet
Member
This is pretty simple to configure using TBC. There are two time entries: (a) peak, (b) off-peak
I point out that these periods provide predictable results: (a) peak: ALL solar to grid, house runs of battery (contrary to your @pdxgibby 3rd want) (b) off-peak: PW not allowed to discharge.
The unspecified time (shoulder period) is the most talked about subject. I would say that if you look at daily, it seems inefficient to charge solar during the shoulder period and discharge during the shoulder period later in the day. What I did not know, and often missed is that if you step back and look at it from a week-long perspective, this sour point becomes a positive. (Solar undersized by the way). The batteries get fully charged during the weekend. As each day passes, the SOC at the start of the day gets lower and lower. By Friday, it is practically empty to the reserve by Friday midnight. On Saturday, weather permitting, solar generated goes to the battery at OFF-PEAK, and stores for the week to come. After Sunday, batteries are almost full ready to tackle the work week. Even with undersized solar, no problem filling the batteries up because the off-peak hours on weekends are plenty. There is no off-peak hours when the sun shines weekdays.
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I agree with this. However, the fact remains that it would be more efficient to just stop charging and go into Standby than to discharge in the same Shoulder period that just charged the batteries. If the system knows how much energy it wants to add by the beginning of the Peak period, at some point a couple hours before the Peak period starts it should just set the charging power to a fixed value that will hit the target and let the variable remaining solar go to the grid.
Some of what you want may be possible if you keep the solar CTs disconnected, forever. As in they are not connected during commissioning or any time afterwards.
I had mine connected and enabled, and now I'm locked in -- as in any amount of going through the wizard to disable the CTs, or physically disconnecting the solar CTs will not restore grid-charging.
So:
1) no problem in any configuration as long as PWs configured that period as off-peak
2) only if PWs configured as non-PV installation
3) only if PWs configured as non-PV installation, in self-consumption, or is in backup-mode
4) only if PWs configured as non-PV installation, in self-consumption, or is in backup-mode
5.1, 5.2) "always" done in any configuration except: in configured peak-period, TBC shoulder, or backup-mode. No problem in self-consumption.
Did you try setting the solar CTs as additional site CTs? Most likely there is a back-end configuration option that you would need Tesla to disable. There's always spoofing the CTs to get it to grid charge . . .
Cheers, Wayne
Wouildn't setting "solar" CTs as site CTs cancel or throw off the primary site CTs? I'm now researching how to spoof the solar CTs. Maybe take one end of each CT and wind it a few times around a grid cable.
I also have an additional Neurio (and 2 more pairs of CTs) to try if I can figure out how to get the Gateway to attach to it. I'm not sure a consumer Neurio is sync-compatible if Tesla uses a custom protocol.
The only other options I had seen was "Load" which would almost impossible to gather/sort in my subpanel as all the load wiring is black, and I can't understand yet how it would work.
If you want to get Powerwall to ignore your solar production and just track your consumption, you need to set set the solar CTs to Load or Site with the correct sign choice.
When your have solar production, the main Site CTs detect your net consumption (consumption minus solar production), and so to calculate your actual consumption, the Powerwall adds your production from the Solar CTs to the main Site CTs to get your total consumption.
So setting the solar CTs to Load or Site with the correct sign should reproduce this behavior as far as calculating total consumption, while not telling Powerwall you have solar.
If you just disable the solar CTs, then the Powerwall will only see your net consumption.
Cheers, Wayne
P.S. I assume on step 6/12 in the wizard you deleted your solar generator?
When your have solar production, the main Site CTs detect your net consumption (consumption minus solar production), and so to calculate your actual consumption, the Powerwall adds your production from the Solar CTs to the main Site CTs to get your total consumption.
So setting the solar CTs to Load or Site with the correct sign should reproduce this behavior as far as calculating total consumption, while not telling Powerwall you have solar.
If you just disable the solar CTs, then the Powerwall will only see your net consumption.
Cheers, Wayne
P.S. I assume on step 6/12 in the wizard you deleted your solar generator?
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