Did I just experience the lack of Black Start capability?

[GregBallantyne]

I use the term Black Start from my old Power Generation Station engineering days....it refers to a Power Plant's ability (or lack thereof) to initiate operation without grid power.

My Tesla generation system has been in operation for a year now, during which we've had 29 grid power interruptions. Two of those were noticeable without referring to the app, the second of which was within the last hour.

This time, after the noticeable power interruption, the Powerwalls took over but solar production ceased. The app periodically showed .2 or .3 kw Solar, but mostly zero. After about 15 minutes, the app informed me that grid reconnection was underway. This was a process I had not seen previously - in the past I've been looking at the app when grid power resumed, and the red X simply disappeared. Of course, in the past solar production was not interrupted either. That reconnection process took another 10 minutes or so, long enough for me to check my grid operator's app which assured me that my grid power was on. I guess the Gateway was booting up, and solar production resumed.

I think this may have been the lack of Black Start capability I've heard about. If grid power had not resumed, my system may not have resumed solar generation, and after battery depletion we would have lost power to the house. Can anyone with knowledge about this confirm? Please keep in mind that in my Power Engineering career I was a piping engineer, not an electrical engineer..... thanks

Edit:
My Powerwalls were at 96% SOC and accepting about 11kw when the grid power went out. It just occurred to me that the high SOC may have resulted in a similar reaction by the Gateway.

 

[power.saver]

I use the term Black Start from my old Power Generation Station engineering days....it refers to a Power Plant's ability (or lack thereof) to initiate operation without grid power.

My Tesla generation system has been in operation for a year now, during which we've had 29 grid power interruptions. Two of those were noticeable without referring to the app, the second of which was within the last hour.

This time, after the noticeable power interruption, the Powerwalls took over but solar production ceased. The app periodically showed .2 or .3 kw Solar, but mostly zero. After about 15 minutes, the app informed me that grid reconnection was underway. This was a process I had not seen previously - in the past I've been looking at the app when grid power resumed, and the red X simply disappeared. Of course, in the past solar production was not interrupted either. That reconnection process took another 10 minutes or so, long enough for me to check my grid operator's app which assured me that my grid power was on. I guess the Gateway was booting up, and solar production resumed.

I think this may have been the lack of Black Start capability I've heard about. If grid power had not resumed, my system may not have resumed solar generation, and after battery depletion we would have lost power to the house. Can anyone with knowledge about this confirm? Please keep in mind that in my Power Engineering career I was a piping engineer, not an electrical engineer..... thanks

Edit:
My Powerwalls were at 96% SOC and accepting about 11kw when the grid power went out. It just occurred to me that the high SOC may have resulted in a similar reaction by the Gateway.

Yes, it is likely that the 96% SOC was the problem. It shut off the solar as soon as the outage occurred, and wouldn't let it resume until the SOC drops, typically to 85% - 90% SOC. It sounds like it worked as designed.

 

[GregBallantyne]

Yes, it is likely that the 96% SOC was the problem. It shut off the solar as soon as the outage occurred, and wouldn't let it resume until the SOC drops, typically to 85% - 90% SOC. It sounds like it worked as designed.

Confirmed.... happened again, this time with PWs at 100% SOC. Same response, but without any noticeable interruption. On a sunny day with high atmospheric pressure, beautiful weather. Electrical grid power in some parts of Maryland has more reliability problems than many realize.... the top reason I invested in the system.

 

[wwu123]

Confirmed.... happened again, this time with PWs at 100% SOC. Same response, but without any noticeable interruption. On a sunny day with high atmospheric pressure, beautiful weather. Electrical grid power in some parts of Maryland has more reliability problems than many realize.... the top reason I invested in the system.

I guess add tornados to the list of problems, going forward, if I read the news right this week?

 

[GregBallantyne]

I guess add tornados to the list of problems, going forward, if I read the news right this week?

I think you did. They aren't unheard of around here, but 7 in one day are more than I recall ever hearing about in a season. All within 50 miles of here. But we all are going to get more familiar with what climate change looks like I reckon, no matter if we want to or not.... the tornados aren't the only aspect we're seeing here tho.
Makes me want a few more PWs.

 

[BGbreeder]

I use the term Black Start from my old Power Generation Station engineering days....it refers to a Power Plant's ability (or lack thereof) to initiate operation without grid power.

My Tesla generation system has been in operation for a year now, during which we've had 29 grid power interruptions. Two of those were noticeable without referring to the app, the second of which was within the last hour.

This time, after the noticeable power interruption, the Powerwalls took over but solar production ceased. The app periodically showed .2 or .3 kw Solar, but mostly zero. After about 15 minutes, the app informed me that grid reconnection was underway. This was a process I had not seen previously - in the past I've been looking at the app when grid power resumed, and the red X simply disappeared. Of course, in the past solar production was not interrupted either. That reconnection process took another 10 minutes or so, long enough for me to check my grid operator's app which assured me that my grid power was on. I guess the Gateway was booting up, and solar production resumed.

I think this may have been the lack of Black Start capability I've heard about. If grid power had not resumed, my system may not have resumed solar generation, and after battery depletion we would have lost power to the house. Can anyone with knowledge about this confirm? Please keep in mind that in my Power Engineering career I was a piping engineer, not an electrical engineer..... thanks

Edit:
My Powerwalls were at 96% SOC and accepting about 11kw when the grid power went out. It just occurred to me that the high SOC may have resulted in a similar reaction by the Gateway.

It is my understanding that the grid reconnection process includes checks for grid stability, with a lockout time that is said to be on the order of five minutes, although I have seen reconnection occurring a shorter period of time. I can imagine scenarios when there might grid events, e.g. loose connections, branches touching wires, or voltages that go out of range, any of which might lengthen the time to reconnection.

Perhaps I am not thinking of this correctly, but I think of "black starts" as when things are "lights out". So, in the Powerwall/Gateway environment, I think that would be more analogous to the the Gateway and Powerwall being shutdown due to low SoC, with no grid, no stored power,and needing to start from a depleted state, which is when the system requires a little external voltage to power up.

All the best,

BG

 

[dhrivnak]

Assuming the PowerWall is similar to my FranklinWH AC coupled battery, if the batteries are above say 85% solar is turned off if how loads are modest as it has no where to put the power. The FranklinWH, at least on paper, has a good black start capability. A black start is when your battery runs out and the system shuts down. Without Black Start you are dead in the water as there is no power to restart solar. The FranklinWH reserves about a kWh and then at 10:00, 12:00, 14:00, will wake up and see if there is solar power. If so then the system will kick on and start charging the battery and supplying loads. I know some systems, like Generac, require an extra 12V battery for this functionality.

 

[miimura]

In addition to power quality checks when the grid is restored, the Powerwalls also have to align the interter's phase to the grid so that there is no current discontinuity when it closes the automatic grid disconnect switch in the Gateway (or Backup Switch meter socket thingy).

 

[GregBallantyne]

I have read that Powerwalls won't fully discharge during an extended grid outage, which causes me to wonder it that is only for battery protection or if there is some degraded state in which PW stops powering things, but would provide sufficient power to start things if solar generation becomes available, like the Franklin WH system? If not, I wonder why.
Yesterday my load center remained energized, so that situation could not be equivalent to a Black Start. My bad....

 

[miimura]

The Powerwall system does shut down early (5%-10% SOC) so that it has sufficient energy to start up again when it thinks there will be solar available to recharge the batteries.

I have also run into the situation where the Powerwalls think they are overloaded when the grid fails. The app put up a message like "Grid Outage: Powerwall Inactive". I then had to shut off all the load breakers in order to get the Powerwalls to dark start and power the house. After they're running, I can turn on all the loads and it powers the house just fine. Tesla Support was unable to explain what happened.

 

[GregBallantyne]

So some level of Black Start capacity exists, up to the point insufficient charge remains in PWs to power on the system. Good....

 

[jjrandorin]

So some level of Black Start capacity exists, up to the point insufficient charge remains in PWs to power on the system. Good....

This Tesla website has information that I feel is relevant:

Best Practices During Power Outages | Tesla Support

Powerwall brings you energy independence and security, so life in your home can carry on uninterrupted when the grid goes down. Learn more about how Powerwall functions during extended power outages.

www.tesla.com

There is also a thread here on starting powerwalls without grid power, which might be of interest to you:

PowerWall Cold Start without Grid Power

In an experiment today, my PoweWall/Gateway setup would not start without Grid Power. Here is the sequence that I followed to do a cold restart of my system that consists of a 125A breaker on my main panel feeding a gateway connected to a backup panel and a generation panel with 9.9 kW of Solar...

teslamotorsclub.com

Buried in this thread is a video (hopefully its still there) that shows unboxing and starting powerwalls that were provided for power in an emergency situation:

https://insideevs.com/news/572963/tesla-powerwall-how-to-video-for-ukraine/

 

[GregBallantyne]

This Tesla website has information that I feel is relevant:

Best Practices During Power Outages | Tesla Support

Powerwall brings you energy independence and security, so life in your home can carry on uninterrupted when the grid goes down. Learn more about how Powerwall functions during extended power outages.

www.tesla.com

There is also a thread here on starting powerwalls without grid power, which might be of interest to you:

PowerWall Cold Start without Grid Power

In an experiment today, my PoweWall/Gateway setup would not start without Grid Power. Here is the sequence that I followed to do a cold restart of my system that consists of a 125A breaker on my main panel feeding a gateway connected to a backup panel and a generation panel with 9.9 kW of Solar...

teslamotorsclub.com

Buried in this thread is a video (hopefully its still there) that shows unboxing and starting powerwalls that were provided for power in an emergency situation:

https://insideevs.com/news/572963/tesla-powerwall-how-to-video-for-ukraine/

Thanks for this, some informative stuff. Since my system is whole house backup, I don't have a backup panel as described in the TMC thread, and with 3 PWs I am quite unlikely to see an overload shutdown. I have an as yet untried strategy in mind for an extended grid outage that might put us into a situation that could reveal some of these limitations - which is when PWs reach a low around 5%, throw my main to isolate the house from the system and provide power by backfeeding the main panel from a generator thru an outbuilding subpanel, as I used to do before getting the solar system. Then the sun would at some point again charge the PWs, enabling them to resume providing main load center powering. That should avoid seeing a true Black Start situation.