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New Powerwall Advanced Options [Toggles for charging from and discharging to grid from powerwalls]

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Can you point me to the regulation which specifies that grid parallel systems using CT's and software require PTO as you describe?
Take a look at this thread:


Cheers, Wayne
 
I’m trying to wrap my head around how to use this option from an operational perspective - it doesn’t seem to be a set it and forget it option.

If I understand this correctly, when turned on, the grid will only charge the battery when SOC is below the set reserve. But as long as you are connected to the grid the battery SOC will never go below the reserve so the grid will never charge the battery (ignoring phantom drain).

So to use this new feature in addition to turning it on, I have to manually set the reserve to something above the current SOC. I don’t see a way to have the battery cover the house usage during peak and partial peak times, then have the grid recharge the battery during off-peak unless I intervine either manually or with a script.

Am I missing something?
 
Yes, as per post #13 in this thead: The web page in the OP says "When set to ‘Yes,’ Powerwall will charge from the grid if there is insufficient solar available to maintain the Backup Reserve or if there is a financial benefit when in Time-Based Control mode."

Cheers, Wayne
I cannot even get the option yet.

My reserve is set at 10%. I see no reason to try and set to 100% when I do not even have the option
 
I cannot even get the option yet.

My reserve is set at 10%. I see no reason to try and set to 100% when I do not even have the option
They probably saw how much solar you have and figured you have no use for the option... I am sure it will show up eventually, Tesla usually slowly releases new features for everyone similar to the new impact cards.
 
I’m trying to wrap my head around how to use this option from an operational perspective - it doesn’t seem to be a set it and forget it option.

If I understand this correctly, when turned on, the grid will only charge the battery when SOC is below the set reserve. But as long as you are connected to the grid the battery SOC will never go below the reserve so the grid will never charge the battery (ignoring phantom drain).

So to use this new feature in addition to turning it on, I have to manually set the reserve to something above the current SOC. I don’t see a way to have the battery cover the house usage during peak and partial peak times, then have the grid recharge the battery during off-peak unless I intervine either manually or with a script.

Am I missing something?
I flipped charge from grid on last night. Reserve was set to 20%. SOC was at 10%. It charged the powerwall up to 100% using super off peak rates all last night. Now I am just selling all solar back to the grid …

It is certainly realizing that with TOU, this is the new winning recipe :)

Question for others - how can I prevent any future updates that could remove this feature :)
 
Wow, awesome move by Tesla. I'll be watching this closely as this develops. I do see the option to charge from the grid in my app since I updated it.

This also influences the decision to take the ITC, as I want to stay on the up and up. I believe to take the ITC you have to charge those batteries at least 75% from renewable resources. So I think I could do some grid charging and still take the ITC.

One thing that isn't really discussed here is that with grid charging enabled, the warranty has somewhat reduced effectiveness. It's probably not enough for most people to really mind, since the difference between 47.5MWh and 37.8 MWh after 10 years isn't huge. Most people likely cannot fill and empty the Powerwall each day, 365 days per year, but most can do that 75% of the time.

So even if you tried to get a nearly full 13 kWh cycle out of each battery by charging only from solar, you still wouldn't likely end up with a lot more than 37.8 MWh of throughput after 10 years unless you lived in an area with great year-round irradiance, and had low battery degradation.
 
This also influences the decision to take the ITC, as I want to stay on the up and up. I believe to take the ITC you have to charge those batteries at least 75% from renewable resources. So I think I could do some grid charging and still take the ITC.
My recollection is that IRS guidance on when an ESS qualifies for the residential ITC is unclear. For the commercial ITC is it 75% or more charging from PV, for 5 years, and the credit is pro-rated if it's under 100%, IIRC. For the residential ITC, I recall another (non-binding) interpretation letter calling for 100% ESS charging from PV, without mention of a time period.

Cheers, Wayne
 
Take a look at this thread:
Thank you. A nice deep dive, that.

In the process I looked up PG&E's non-export interconnection page. I didn't drill deeper, but it looks like a well qualified non-exporting solar system may be able to avoid NEM for an $800 fee. So even if PTO is required, NEM may not be.

My friend's supplier seems to suggest a "don't ask, don't tell", real world practical sort of approach. They say the utility has no way to tell if a non-exporting solar system is connected. I do wonder what penalty might apply if one gets caught, or would it just be the $800 fee.
 
This also influences the decision to take the ITC
We've had our PowerWall for a couple years. I did a calculation about how much grid charging would save me, and it was only $39 for the year. This undoubtably would not justify skipping the tax credit. Our PW was paid for by SGIP, so we did opt not to take the credit.

Our annual true-up runs around $60, so that meager $39 savings from grid charging looms much larger that it really is. But this year, after a year of free supercharging, we started charging our car at home. We beefed up our solar a bit, limited by what our single PW can handle, so all bets are off...

I found my notes, so here is some detail on my calculation. Our daily PW discharge during peak periods is ~50%, i.e. ~7kWh. We are on PG&E EV2-A, NEM1, with an assumed difference between part peak and off peak of $.20. I compared our daily production for a year Enphase data with hourly consumption. (Yes, an 8,760 line Excel sheet) On 51 days, our production was less than our peak consumption, totaling 194 kWh, so that is how much grid charging we would need. Hence $38.80. Precise but not very accurate because I did not simulate the actual state of charge, and a after the first cloudy day, the battery would still have some useable charge.

Far be it from me to advise anyone to cheat on the ITC rules, but Tesla's own Storm Watch does grid charge. And 194 kWh is peanuts. So I'd probably grid charge even if I had taken ITC. I think the ITC should be applied to storage anyway. Storage, with or without solar, lets one stay off the grid during peak times, hence saving everyone money, us, pg&e, and all their other customers too. ITC should be deployed to incentivize this, just like solar, in my opinion.
 
I blame PG&E. And that we didn’t go thru Tesla for our systems.
Tesla was not my installer, but mine does show gird charging.

The scree the app brings up when you click to allow grid charging puts the utility approval and ITC on you, see below. I ed

I suspect there is a glitch in the configuration of your account on Tesla's servers. I saw this sort of issue when mine at first showed no notification options, and again later when rate plans didn't show up. Tesla Energy Support fixed both of these, somehow.

IMG_7727.png
IMG_7728.png
 
I flipped charge from grid on last night. Reserve was set to 20%. SOC was at 10%. It charged the powerwall up to 100% using super off peak rates all last night. Now I am just selling all solar back to the grid …

It is certainly realizing that with TOU, this is the new winning recipe :)

Question for others - how can I prevent any future updates that could remove this feature :)

Thank you. A nice deep dive, that.

In the process I looked up PG&E's non-export interconnection page. I didn't drill deeper, but it looks like a well qualified non-exporting solar system may be able to avoid NEM for an $800 fee. So even if PTO is required, NEM may not be.

My friend's supplier seems to suggest a "don't ask, don't tell", real world practical sort of approach. They say the utility has no way to tell if a non-exporting solar system is connected. I do wonder what penalty might apply if one gets caught, or would it just be the $800 fee.
I would be much more concerned if one had a fire, and insurance WOULD NOT cover!!1
 
May be try to uninstall your app and reinstall or call tesla to ask why you don't get it in your app. It seems like most people get it.
Yep, have tried all of that. seems I have the same GW fw as others, and phone app. So, no idea. Guess having to call is my only option.

But for me, it really is a do not care 99% of the time. I can only think of once or twice in the winter I did not have enough solar to recharge the batteries, but we had a super mild summer. And since I have so much solar, saving money is a total do not care!!!
 
Also, I have the older Powerwall 2s and separate gateway, not Powerwall+ with the integrated gateway.
Need to be careful about the terminology. The Powerwall+ integrates the solar inverter with the Powerwall, and the processor board in the solar inverter can perform the same supervisory functions of the processor board in the gateway. But the contactor (relay) and some sensing functions of the gateway are not integrated into the Powerwall+; the Backup Switch has to be paired with the Powerwall+ to implement the gateway functionality.
 
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Day 2. Woke up to 100% charge again. Currently selling all solar back at off-peak (0.37c) rates.

Going to need to find some way use more electricity to offset all of the credits. 😳
 

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