Powerwall Stormwatch

[Brovane]

I had the Stormwatch featured activated, for the first time in Southern CA because of the high winds I assume.

It immediately drew power from both Solar and Grid to charge the PW to maximum capacity. I did however notice that the system seemed to continue to charge even after it showed 100% for a much longer time than usual. I switched off Stormwatch this afternoon around 1:30pm and the PW's started discharging. However the PW's seemed to discharge for almost 2-hours despite a 1.5kw+ continuous draw before the % dropped below 100%.

Has anyone else seen this behavior with Stormwatch? I am thinking that the PW rating of 100% in the App isn't actually 100% of the rated capacity of the PW units. Maybe it is actually 90% of capacity to help prolong the life of the battery. However if Stormwatch activates then the full capacity of PW unit is activated which basically charged the unit above the 100% bar displayed on the app.

 

[power.saver]

The % shown on the app doesn't always match the reported % in the battery, especially at the low end. And, since battery full is a function of energy in versus energy out, it is reconciled at full charge. Meaning that even though the total energy in should make it full, if the battery will accept more, it will charge more, but the reporting will stay at 100%. I've seen charging on mine (not during stormwatch) where it reaches 100% but continues for a while longer, until the battery is actually full. Upon starting discharge, I often go an hour before 99% shows, so this is not unusual.

 

[Brovane]

The % shown on the app doesn't always match the reported % in the battery, especially at the low end. And, since battery full is a function of energy in versus energy out, it is reconciled at full charge. Meaning that even though the total energy in should make it full, if the battery will accept more, it will charge more, but the reporting will stay at 100%. I've seen charging on mine (not during stormwatch) where it reaches 100% but continues for a while longer, until the battery is actually full. Upon starting discharge, I often go an hour before 99% shows, so this is not unusual.

I have seen the same behavior multiple times. However this time I have never seen it go on charging for so long after the Application showed 100% charge and it discharge for so long before it dropped below 100%.

 

[nyprepper]

Wow, let me make sure I understand this. In stormwatch mode ON, the PW will charge from solar AND the grid??? is it just a matter of having stormwatch switched ON via the app??? thx

 

[eml2]

Wow, let me make sure I understand this. In stormwatch mode ON, the PW will charge from solar AND the grid??? is it just a matter of having stormwatch switched ON via the app??? thx

Yes, it will charge from the grid, but only when Storm Watch mode is both ON and ACTIVE. You toggle the switch on the app to turn it on. However, it will become active only when the National Weather Service issues a High Wind Warning in your area.

 

[MorrisonHiker]

Yes, it will charge from the grid, but only when Storm Watch mode is both ON and ACTIVE. You toggle the switch on the app to turn it on. However, it will become active only when the National Weather Service issues a High Wind Warning in your area.

Hopefully it will also work with blizzard warnings and other weather alerts.

 

[montreid]

OP - same here. I think it's like how they like us to have SOC max 90% for regular, but allow 100% SOC on trips. In this case -- Storm watch will allow to 100% SOC. Same thing here; charged to 100% overnight, and when we hit Peak today, I turned off and ran about two hours discharge before dipping down on the app. Currently 85% heading into hour three, which usually would be about 75% by now.

Presume the storm watch is tied to the weather service alert. Will turn that back on this evening to recharge at low rates while we can

 

[Dukeybootie]

If you charge from the grid, even if only during Storm Watch mode, would that still impact ITC eligibility?

 

[Brovane]

Some additional data.

On Saturday my Power-wall went into Storm Watch mode. It was at 46% charge for two PW2 units. Which indicates a charge of about 12.4 kwh stored in the batteries. The unit over the next several hours had 19.1 kwh sent to the PW2 unit according to the APP. This would indicate a capacity of more than 27 kwh when the unit is in storm watch mode. While there is some variability with the SOC %, this is still considerably above what we consider the normal capacity of the unit. Also while at 100% SOC on the APP the unit was still charging at 5 kw, normally it is ramping the charge rate down when 100% is reached.

This evening the unit went out of Storm Watch mode and the house started drawing on the power-wall. The unit discharged a total of 3 kwh before it dropped to 99% SOC. This figure seems to correspond closely with the hunch that the standard day-to-day usage of the PW is about 90% of it's actual full capacity and that Stormwatch mode allows the usage of this 90-100% capacity of the battery.

 

[NuShrike]

Some additional data.

On Saturday my Power-wall went into Storm Watch mode. It was at 46% charge for two PW2 units. Which indicates a charge of about 12.4 kwh stored in the batteries. The unit over the next several hours had 19.1 kwh sent to the PW2 unit according to the APP. This would indicate a capacity of more than 27 kwh when the unit is in storm watch mode. While there is some variability with the SOC %, this is still considerably above what we consider the normal capacity of the unit. Also while at 100% SOC on the APP the unit was still charging at 5 kw, normally it is ramping the charge rate down when 100% is reached.

This evening the unit went out of Storm Watch mode and the house started drawing on the power-wall. The unit discharged a total of 3 kwh before it dropped to 99% SOC. This figure seems to correspond closely with the hunch that the standard day-to-day usage of the PW is about 90% of it's actual full capacity and that Stormwatch mode allows the usage of this 90-100% capacity of the battery.

So much like the Tesla vehicles, there's a spare capacity for emergency reasons.

 

[Shygar]

When using the API to query the powerwall, I noticed a 3% difference between what the app reports and what the API reports. It's interesting that the stormwatch is setup to take advantage of this extra storage.

I am very curious though how it charged from the grid. Has anyone else experienced that? This could be a problem for the ITC right? I think it has to charge from solar at least 75% of the time right? Maybe Tesla is keeping track of this percentage and letting some grid charge in certain situations. This would be great if so.

What software version are you on with your powerwalls? 1.26.0?

 

[cwied]

When using the API to query the powerwall, I noticed a 3% difference between what the app reports and what the API reports. It's interesting that the stormwatch is setup to take advantage of this extra storage.

I am very curious though how it charged from the grid. Has anyone else experienced that? This could be a problem for the ITC right? I think it has to charge from solar at least 75% of the time right? Maybe Tesla is keeping track of this percentage and letting some grid charge in certain situations. This would be great if so.

The 3% difference is only in the middle of the charge range. When the app shows 100%, the API shows 99.993% for my Powerwalls. I suspect there is a reserve over and above this that is used in Stormwatch.

As far as the ITC goes, you have to charge only from solar in order to qualify. The proration with 75% minimum is for commercial installations only (ref: 2018 Energy Storage Tax Credits Explained | EnergySage). I think this may be a case of where Tesla may be hoping it will not be enforced that strictly. Nevertheless I've turned off Stormwatch for now.

 

[NuShrike]

The 3% difference is only in the middle of the charge range. When the app shows 100%, the API shows 99.993% for my Powerwalls. I suspect there is a reserve over and above this that is used in Stormwatch.

As far as the ITC goes, you have to charge only from solar in order to qualify. The proration with 75% minimum is for commercial installations only (ref: 2018 Energy Storage Tax Credits Explained | EnergySage). I think this may be a case of where Tesla may be hoping it will not be enforced that strictly. Nevertheless I've turned off Stormwatch for now.

Maybe there is an "emergency" clause somewhere that would allow temporary charging from the grid.

Remember how long it took for Telsa to release TBC when they mentioned it was delayed due to navigating regulations. What regulations would there have been to delay TBC for so long? -- especially when it's nothing that special any coder couldn't have written up and deployed in less than a month.

To think a governing agency would ban any charging that would stabilize homes/grids, under special circumstances, just because it would violate rebate terms makes it seem short-sighted and counter-productive.

It would be nice if Tesla specifically clarified this question.

 

[nyprepper]

i just did a test.... set system to self-power and ran down Powerwall's to 90%. set system back to backup power only. the house is now back to drawing from the grid, but the grid is not charging-up the Powerwalls. My area is currently under a Winter Storm Warning notice from the National Weather Service. Or maybe it has to be set to Storm Watch when the alert is first issued??? Maybe there is some latency? Oh well.

 

[Shygar]

I think the idea is to charge up the powerwall before the storm hits. So if you switch to it during a storm, it may not have the same effect. Just speculating here.

 

[MorrisonHiker]

i just did a test.... set system to self-power and ran down Powerwall's to 90%. set system back to backup power only. the house is now back to drawing from the grid, but the grid is not charging-up the Powerwalls. My area is currently under a Winter Storm Warning notice from the National Weather Service. Or maybe it has to be set to Storm Watch when the alert is first issued??? Maybe there is some latency? Oh well.

Usually there is a lag of an hour or so whenever I change modes. If toggling between Self-powered and TBC, you can see from the Energy Usage screen in the app if it is still actually on Self-powered if it doesn't show the Off-peak and Peak indicators on the graph or the All Day, Peak, Partial-Peak and Off-Peak filters below the graph. There's a similar difference that you can see on the main screen to tell if it is really on Backup or Self-powered. I can't remember the exact wording, but look at the Performance section (or if it's missing). Self-powered and TBC will mention your self-powered percentage but Backup shows something else since it wouldn't normally power things.

 

[JohnRatsey]

The 3% difference is only in the middle of the charge range. When the app shows 100%, the API shows 99.993% for my Powerwalls. I suspect there is a reserve over and above this that is used in Stormwatch.

There seems to be a linear relationship between app SoC and API SoC with both agreeing on 100% and 0% on the app being 5% according to the battery API. This is the point at which the battery stops delivering power but still sits on standby and slowly uses the remaining charge.

 

[eml2]

i just did a test.... set system to self-power and ran down Powerwall's to 90%. set system back to backup power only. the house is now back to drawing from the grid, but the grid is not charging-up the Powerwalls. My area is currently under a Winter Storm Warning notice from the National Weather Service. Or maybe it has to be set to Storm Watch when the alert is first issued??? Maybe there is some latency? Oh well.

Last time my Storm Watch was active on 11/2, NWS issued a High Wind Warning. I don't think Winter Storm Warning will trigger it.

I remember NWS issued High Wind Warning on 11/2, and the warning would expire the following day at 7 pm. Because it was issued during my peak hours, I opted not to charge my PW during peak and turned off Storm Watch. Almost immediately it stopped charging from grid. A few minutes later I turned Storm Watch back on but it would not charged from grid.

At 11/2 11 pm, NWS issued another High Wind Warning, and PW started to charge from grid again.

 

[Brovane]

When using the API to query the powerwall, I noticed a 3% difference between what the app reports and what the API reports. It's interesting that the stormwatch is setup to take advantage of this extra storage.

I am very curious though how it charged from the grid. Has anyone else experienced that? This could be a problem for the ITC right? I think it has to charge from solar at least 75% of the time right? Maybe Tesla is keeping track of this percentage and letting some grid charge in certain situations. This would be great if so.

What software version are you on with your powerwalls? 1.26.0?

I am on 1.26.0

 

[NuShrike]

Anybody in SoCal have StormWatch taking action the last few days?

It's been unusually cloudy for this season of June and it would be nice if the PW freshened up from the grid every few days instead of waiting for the lacking solar.