PW recharging behavior with no sun

[BIC1]

Not sure if this is normal or not. Have PW for about 16 months now. Have 12k solar but PW is backup only. Have one PW, been waiting 14 months for second. True operational grid outages in last 16 months have been few and short.

While out of town a couple of weeks ago, during a thunderstorm, grid went out for about one hour and 20 minutes. Was notified by Tesla app. With other apps, I shut down a few systems, such as air conditioners. Nonetheless, in that 1+20, my PW dropped from about 98-99% to 79%. Most of the time, baseline power consumption is about 1.1kW, which includes a couple of dehumidifiers. Does a 20% drop in battery level seem right?

After grid resumed, weather was overcast/rainy and PW did not top off. Apparently, I'm not setup to recharge from grid. It remained overcast/rainy for a couple of days with no charging. My concern is another grid outage and my battery is low when it could have been topped off while grid was on.

Can I/should I have grid charging of PW for backup when no sun? If so, who does that? Me, 3rd party installer or Tesla?

On a side note. After grid went down and on PW, I initially had Internet to operate home apps. After a few minutes Spectrum Cable Internet apparently went down and resumed about same time as grid came back up. Does cable Internet typically go out with grid? Thanks.

 

[h2ofun]

Not sure if this is normal or not. Have PW for about 16 months now. Have 12k solar but PW is backup only. Have one PW, been waiting 14 months for second. True operational grid outages in last 16 months have been few and short.

While out of town a couple of weeks ago, during a thunderstorm, grid went out for about one hour and 20 minutes. Was notified by Tesla app. With other apps, I shut down a few systems, such as air conditioners. Nonetheless, in that 1+20, my PW dropped from about 98-99% to 79%. Most of the time, baseline power consumption is about 1.1kW, which includes a couple of dehumidifiers. Does a 20% drop in battery level seem right?

After grid resumed, weather was overcast/rainy and PW did not top off. Apparently, I'm not setup to recharge from grid. It remained overcast/rainy for a couple of days with no charging. My concern is another grid outage and my battery is low when it could have been topped off while grid was on.

Can I/should I have grid charging of PW for backup when no sun? If so, who does that? Me, 3rd party installer or Tesla?

On a side note. After grid went down and on PW, I initially had Internet to operate home apps. After a few minutes Spectrum Cable Internet apparently went down and resumed about same time as grid came back up. Does cable Internet typically go out with grid? Thanks.

grid charging not allowed unless storm watch kicks in

 

[wjgjr]

To answer your second question first, in the US, virtually nobody has the ability to grid charge their PWs if they also have solar, unless storm watch is activated (generally due to certain severe weather events declared by the National Weather Service, like tropical storm/hurricane warnings or red flag warnings, but it seems not thunderstorm warnings.) There are a number of threads discussing why, but it seems to boil down to some combination of Tesla choosing not to enable it so customers claiming the Investment Tax Credit do not violate the terms of the credit, and the patchwork of utility interconnection rules across the country, some of which may not allow for grid charging.

That said, even with rain/overcast, I would expect your PW to charge back up that 20% over a couple days. It would have to be pretty extreme for my ~8 kW system not to generate ~2.5 kWh over 2 days.

As to your first question, a ~20% depletion of a PW is about 2.5 kWh. (Capacity is 13.5 kWh, but the app numbers may hide some of that, and there might be some degradation.) You indicate that you shut down some systems, but if it was not immediate, or some other loads happened to be running, it would be very reasonable to see that 20% loss in 80 minutes. You could post a screenshot of your usage from the Tesla app for the day to help answer the question, but it seems pretty reasonable.

 

[brkaus]

Cable can go down with the grid. It all depends on how well they have the local nodes backed up.

or your cable modem may have lost power?

 

[jjrandorin]

Can I/should I have grid charging of PW for backup when no sun? If so, who does that? Me, 3rd party installer or Tesla?

No, tesla powerwalls only grid charge if triggered on teslas end by stormwatch, unless one logs in as an installer and re configures some stuff that is not supposed to be touched by the end user.

Whether the internet goes down or not depends on whether the cable providers local equipment (local as in "your neighborhood" not "your house") either lost power, or has a battery backup.

Depending on the scope of the outage, its entirely possible not to have home internet unless you use a hotspot or something. Since you have 12k solar and only 1 powerwall, I hope you discussed what may or may not happen with your home as far as your solar charging your powerwall with no grid with your installer.

Finally, 20% of 13.5 (powewall capacity) is 2.7. Its not out of the realm of possibility that you used 2.5kWh to 2.7kWh of energy in an hour and half.

 

[BIC1]

Screenshot of day in question, 6/25/21, attached. Grid outage approximately 1745 - 1850.

App was set with Storm Watch on but don't know if it was actually activated. I don't remember seeing it, but hard to say at this point. I've seen the Storm Watch activated maybe five times in 14 months? Hard to remember. I'll make note of activation in future. Of course, it may be after the storm passes that you need to recharge from the grid, so even if Storm Watch activated before & during storm, probably goes off after storm, which is when need it on for grid charging.

It was a very extreme storm. Don't think my cable modem lost power. I have several components, including that one, that are on UPS, as well as Powerwall.

Yes, PW did charge back up over the next couple of days. I may have overstated that a bit. Sorry.

 

[BIC1]

No, tesla powerwalls only grid charge if triggered on teslas end by stormwatch, unless one logs in as an installer and re configures some stuff that is not supposed to be touched by the end user.

Whether the internet goes down or not depends on whether the cable providers local equipment (local as in "your neighborhood" not "your house") either lost power, or has a battery backup.

Depending on the scope of the outage, its entirely possible not to have home internet unless you use a hotspot or something. Since you have 12k solar and only 1 powerwall, I hope you discussed what may or may not happen with your home as far as your solar charging your powerwall with no grid with your installer.

Finally, 20% of 13.5 (powewall capacity) is 2.7. Its not out of the realm of possibility that you used 2.5kWh to 2.7kWh of energy in an hour and half.

Is there any downside to having installer set PW to charge from grid. Presume it would only do that if no solar available?

After first PW was installed, I came to understand I needed two, which is why I've been waiting 14 months for #2.

 

[h2ofun]

Is there any downside to having installer set PW to charge from grid. Presume it would only do that if no solar available?

After first PW was installed, I came to understand I needed two, which is why I've been waiting 14 months for #2.

No installer will/can legally setup to charge from the grid, unless no solar.

 

[h2ofun]

Screenshot of day in question, 6/25/21, attached. Grid outage approximately 1745 - 1850.

App was set with Storm Watch on but don't know if it was actually activated. I don't remember seeing it, but hard to say at this point. I've seen the Storm Watch activated maybe five times in 14 months? Hard to remember. I'll make note of activation in future. Of course, it may be after the storm passes that you need to recharge from the grid, so even if Storm Watch activated before & during storm, probably goes off after storm, which is when need it on for grid charging.

It was a very extreme storm. Don't think my cable modem lost power. I have several components, including that one, that are on UPS, as well as Powerwall.

Yes, PW did charge back up over the next couple of days. I may have overstated that a bit. Sorry.

You would know if your battery is being charged from grid in storm watch, It pegs the setup

 

[wjgjr]

Screenshot of day in question, 6/25/21, attached. Grid outage approximately 1745 - 1850.

App was set with Storm Watch on but don't know if it was actually activated. I don't remember seeing it, but hard to say at this point. I've seen the Storm Watch activated maybe five times in 14 months? Hard to remember. I'll make note of activation in future. Of course, it may be after the storm passes that you need to recharge from the grid, so even if Storm Watch activated before & during storm, probably goes off after storm, which is when need it on for grid charging.

It was a very extreme storm. Don't think my cable modem lost power. I have several components, including that one, that are on UPS, as well as Powerwall.

Yes, PW did charge back up over the next couple of days. I may have overstated that a bit. Sorry.

It does seem based on your timeline that you did not have any spikes during the outage, so the drop in battery output is a bit above what I would expect, but it is still possibly in range (hard to be exact.) Also note, from another current thread, that some users have seen some degradation in their PWs even over the first couple years, which would also mean the percentages drop faster.

If your modem was backed up, it does seem likely it was on the cable company's end, particularly since it worked for a few minutes after the outage.

Is there any downside to having installer set PW to charge from grid. Presume it would only do that if no solar available?

After first PW was installed, I came to understand I needed two, which is why I've been waiting 14 months for #2.

As others noted, it is essentially not possible. As you are probably aware, there is currently a 26% federal credit (the ITC) for solar installs (which should also include adding an additional PW, as you are doing.) But, the general understanding (and a tax expert can give you authoritative information) is that it requires the PW to be charged exclusively from solar. So, the downside of this setting is losing out on this credit. But, because so many US customers claim the credit, and because some utilities also prohibit/discourage grid charging, Tesla just has a blanket policy disallowing it.

There has been one report of a customer who fought to get Tesla to enable this feature. I think it took a lot of time and required the customer both to sign a letter promising not to claim the ITC and to get a letter from the utility explicitly authorizing the setup. It is not clear if Tesla would do this again, even if pushed. Perhaps at some point if the rules around the federal credit change, Tesla might move to make this option more available where utilities allow it.

 

[h2ofun]

It does seem based on your timeline that you did not have any spikes during the outage, so the drop in battery output is a bit above what I would expect, but it is still possibly in range (hard to be exact.) Also note, from another current thread, that some users have seen some degradation in their PWs even over the first couple years, which would also mean the percentages drop faster.

If your modem was backed up, it does seem likely it was on the cable company's end, particularly since it worked for a few minutes after the outage.



As others noted, it is essentially not possible. As you are probably aware, there is currently a 26% federal credit (the ITC) for solar installs (which should also include adding an additional PW, as you are doing.) But, the general understanding (and a tax expert can give you authoritative information) is that it requires the PW to be charged exclusively from solar. So, the downside of this setting is losing out on this credit. But, because so many US customers claim the credit, and because some utilities also prohibit/discourage grid charging, Tesla just has a blanket policy disallowing it.

There has been one report of a customer who fought to get Tesla to enable this feature. I think it took a lot of time and required the customer both to sign a letter promising not to claim the ITC and to get a letter from the utility explicitly authorizing the setup. It is not clear if Tesla would do this again, even if pushed. Perhaps at some point if the rules around the federal credit change, Tesla might move to make this option more available where utilities allow it.

Not everyone gets the ITC, but Tesla just keeps their head in the sand. Only needed for winter. Oh well, if I get my 30KW of panels, would not matter, I hope

 

[jjrandorin]

Is there any downside to having installer set PW to charge from grid. Presume it would only do that if no solar available?

After first PW was installed, I came to understand I needed two, which is why I've been waiting 14 months for #2.

You will not "get installer to set powerwall to charge from the grid", that setting is not available for installers in the US to use unless you dont have solar. Its there because installers in other countries can set it up that way. No installer in the US is going to willingly set that up for you. You would have to hack it yourself, with everything that entails.

EDIT.. I see that this was already stated.

TL ; DR = tesla powerwall + solar, no self charging from the grid without hacking it yourself, in the US.... period, stop, do not pass go.

 

[h2ofun]

You will not "get installer to set powerwall to charge from the grid", that setting is not available for installers in the US to use unless you dont have solar. Its there because installers in other countries can set it up that way. No installer in the US is going to willingly set that up for you. You would have to hack it yourself, with everything that entails.

EDIT.. I see that this was already stated.

TL ; DR = tesla powerwall + solar, no self charging from the grid without hacking it yourself, in the US.... period, stop, do not pass go.

And what I believe happens, is Telsa is logging EVERYTHING that goes on with the TEG. So, if one were to make the easy change in the installer menu, and charge from the grid, seems one maybe opening up the can of worms about warranty support. Even though I know how to do it, I really do not want to go down that path, just seems very risky.

 

[jjrandorin]

And what I believe happens, is Telsa is logging EVERYTHING that goes on with the TEG. So, if one were to make the easy change in the installer menu, and charge from the grid, seems one maybe opening up the can of worms about warranty support. Even though I know how to do it, I really do not want to go down that path, just seems very risky.

I think its a reasonable assumption to make that tesla is logging everything that happens with the device, and charging, etc. The fact that the warranty for the battery has differences if charged from the grid vs charged from solar ( for example) means they have to have some way to determine that. This is the flip side to "always connected" devices.

One has to balance what they are willing to give up, privacy wise, to use certain devices. I know that tesla is likely logging everything with my car and powerwalls, but want those devices anyway so have made peace with that.

I dont, however, have amazon alexa or any type of "im always listening to you" device because I dont feel like what I would gain from having one of those outweighs what I would theoretically lose.

Personal decisions for everyone, for sure.

 

[Redhill_qik]

Screenshot of day in question, 6/25/21, attached. Grid outage approximately 1745 - 1850.

App was set with Storm Watch on but don't know if it was actually activated. I don't remember seeing it, but hard to say at this point. I've seen the Storm Watch activated maybe five times in 14 months? Hard to remember. I'll make note of activation in future. Of course, it may be after the storm passes that you need to recharge from the grid, so even if Storm Watch activated before & during storm, probably goes off after storm, which is when need it on for grid charging.

It was a very extreme storm. Don't think my cable modem lost power. I have several components, including that one, that are on UPS, as well as Powerwall.

Yes, PW did charge back up over the next couple of days. I may have overstated that a bit. Sorry.

It would have been better if you had enable the Powerwall display along with the house. It looks like you had A/C kicking on during the outage, so it would make sense that you used around 2.5 kWh in those 80 minutes.

 

[BIC1]

Here's the better screenshot. As far as spike, think I turned AC off immediately with app, could be one or both dehumidifiers, but don't think one uses that much juice.

Thanks for the explanations re charging for the grid, very helpful in understanding this complicated technology.

 

[jjrandorin]

Here's the better screenshot. As far as spike, think I turned AC off immediately with app, could be one or both dehumidifiers, but don't think one uses that much juice.

Thanks for the explanations re charging for the grid, very helpful in understanding this complicated technology.

You can see in your latest screenshot that your home usage wasnt 1.1kWh during a the time the powerwall was providing energy. You can see the spike up right in the middle of the time period the powerwalls are providing energy. Those spikes are what A/C looks like in use in my house, but my AC spike would be higher.

In any case, the powerwall percentage usage is explained fairly clearly by that screenshot.

 

[Redhill_qik]

Here's the better screenshot. As far as spike, think I turned AC off immediately with app, could be one or both dehumidifiers, but don't think one uses that much juice.

Thanks for the explanations re charging for the grid, very helpful in understanding this complicated technology.

The new graph is showing a Powerwall recharge in the morning when the solar started generated to replace the 0.20-0.25kWh that was lost due to leakage every day. In the Backup mode this usually doesn't happen every morning and only kicks in after it drops 3-5% (every 2-4 days). You mentioned earlier that after the Powerwall covered the home load during the outage and dropped to 79% it didn't recharge the next day. Can you post the same graph options for the next day?

 

[BIC1]

Apparently, I mis-remembered. Looks like it did charge OK the next morning.

 

[Redhill_qik]

Apparently, I mis-remembered. Looks like it did charge OK the next morning.

So, the bottom line is you had a power outage, the Powerwall kicked in and powered your home with maybe a minor interruption with your cable modem/router and then recharged to 100% the next day which is exactly what is expected.