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How come power changeover was not seamless during power outage blip?

h2ofun

Active Member
Aug 11, 2020
3,618
867
auburn, ca
Well, this is interesting. Am sitting at my computer and the screen glitches. I get a text from my Ting line monitoring device that power has gone out, and then was restored "quickly". Looks like a transformer blew in the area, but we had a quick restore. Others are not without power.

But, this knocked out both of my SE inverters and solar stopped, and inverters reset. SO, I guess to say the batteries will make a power outage 100% transparent did not just work for me. Am I expecting too much?
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
14,247
17,984
Riverside Co. CA
You have been here a while so I thought you knew that "100% transparent" depends on the state of your batteries, and solar. Its the middle of the day, in the afternoon. If your batteries are full, then you are exporting solar to the grid. During a power outage in that scenario, there is some switching that goes on.

It depends on if its a clean drop from the power company, whether your powerwalls are full or not, how much your home load is vs your solar production etc.

TL ; DR ... if your powerwalls are already providing your home with power, the changeover is usually seamless. If the powerwalls are NOT providing your home with power (in standby mode because they are full, or in backup only mode), then you you can notice it.

So, no, they did not "fail first test".


(moderator note: I am going to change the thread title to a title thats less clickbait worthy.)
 
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h2ofun

Active Member
Aug 11, 2020
3,618
867
auburn, ca
You have been here a while so I thought you knew that "100% transparent" depends on the state of your batteries, and solar. Its the middle of the day, in the afternoon. If your batteries are full, then you are exporting solar to the grid. During a power outage in that scenario, there is some switching that goes on.

It depends on if its a clean drop from the power company, whether your powerwalls are full or not, how much your home load is vs your solar production etc.

TL ; DR ... if your powerwalls are already providing your home with power, the changeover is usually seamless. If the powerwalls are NOT providing your home with power (in standby mode because they are full, or in backup only mode), then you you can notice it.

So, no, they did not "fail first test".


(moderator note: am going to change the thread title to a title thats less clickbait worthy.)
My PW's were 100% full. Solar was covering house and rest all going to grid. My PW's do not do 100% house until peak at 3 where 100% solar goes to grid. I just thought it was an interesting data point.
 

h2ofun

Active Member
Aug 11, 2020
3,618
867
auburn, ca
SE saw the glitch

glitch.JPG
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
14,247
17,984
Riverside Co. CA
My PW's were 100% full. Solar was covering house and rest all going to grid. My PW's do not do 100% house until peak at 3 where 100% solar goes to grid. I just thought it was an interesting data point.

So, basically what would have happened in that scenario:

1. Batteries 100% full (in standby mode)
2. PV production covering home load with excess going to grid

Power outage (grid disappears)

Excess PV production has no place to go (cant go to powerwalls, they are full, cant go to grid). Gateway sends signal to turn off PV and switch on Powerwalls to cover home load. This takes "milliseconds" but depending on how fast it can switch, will usually be noticed as flickering lights, or even a very brief power interruption.

Take the same scenario above, but make the powerwalls only 60% full (excess PV going to powerwalls, not to grid). If there is a grid outage, excess PV has a place to go (its already going to the powerwalls) so, no grid disruption is noticed.

Switch the scenario to when its peak and you are using a mode which discharges during peak. Home load 100% covered by powerwalls with excess PV going to grid. If power outage happens at this point, the gateway will raise the frequency to turn off the PV, but since the home load is being covered by the powerwalls at that point, home owner likely does not see any transition.

This can be compounded with "ride through" settings where the power may not drop completely from the utility, causing the gateway to not switch as fast.

So, "seamless" depends on a few different factors but mostly whether the powerwalls are full, and whether they are discharging to the home or not already.
 

h2ofun

Active Member
Aug 11, 2020
3,618
867
auburn, ca
So, basically what would have happened in that scenario:

1. Batteries 100% full (in standby mode)
2. PV production covering home load with excess going to grid

Power outage (grid disappears)

Excess PV production has no place to go (cant go to powerwalls, they are full, cant go to grid). Gateway sends signal to turn off PV and switch on Powerwalls to cover home load. This takes "milliseconds" but depending on how fast it can switch, will usually be noticed as flickering lights, or even a very brief power interruption.

Take the same scenario above, but make the powerwalls only 60% full (excess PV going to powerwalls, not to grid). If there is a grid outage, excess PV has a place to go (its already going to the powerwalls) so, no grid disruption is noticed.

Switch the scenario to when its peak and you are using a mode which discharges during peak. Home load 100% covered by powerwalls with excess PV going to grid. If power outage happens at this point, the gateway will raise the frequency to turn off the PV, but since the home load is being covered by the powerwalls at that point, home owner likely does not see any transition.

This can be compounded with "ride through" settings where the power may not drop completely from the utility, causing the gateway to not switch as fast.

So, "seamless" depends on a few different factors but mostly whether the powerwalls are full, and whether they are discharging to the home or not already.
Thanks, makes total sense. PV had no where to go. Was hoping for my first real test, close, but not this time. If I had not gotten the ting report, would have been hard to know it happened.
 
...

...

, the gateway will raise the frequency to turn off the PV, but since the home load is being covered by the powerwalls at that point, home owner likely does not see any transition.

...
Is it the Gateway that increases the frequency or the inverter in the power wall. I think it is the latter. But, I make mistakes, at times. ;)

Unless it just signals the PW inverter to do it.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
14,247
17,984
Riverside Co. CA
Is it the Gateway that increases the frequency or the inverter in the power wall. I think it is the latter. But, I make mistakes, at times. ;)

Unless it just signals the PW inverter to do it.

Im not sure, which device actually raises the power frequency, but my suspicion is that it is the gateway. The gateway is the "computer" in the system, while the powerwalls are basically harddrives / NAS devices (using the computer analogy).

The powerwalls likely report their state / capacity etc to the gateway, but the gateway drives everything is how I think it works (even if the gateway is signaling the powerwall to do something)
 
Am sitting at my computer and the screen glitches. I get a text from my Ting line monitoring device that power has gone out, and then was restored "quickly". Looks like a transformer blew in the area, but we had a quick restore. Others are not without power.

But, this knocked out both of my SE inverters and solar stopped, and inverters reset. SO, I guess to say the batteries will make a power outage 100% transparent did not just work for me. Am I expecting too much?
Yes. The TEG may take several tenths of a second to respond to a surge or brownout and reroute power. That is too long for some electronic devices, which need millisecond response times; a typical UPS responds in ~4 ms. Besides, the TEG will not necessarily protect against surges, so retaining a UPS for your sensitive electronics is still good practice.
 
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h2ofun

Active Member
Aug 11, 2020
3,618
867
auburn, ca
Yes. The TEG may take several tenths of a second to respond to a surge or brownout and reroute power. That is too long for some electronic devices, which need millisecond response times; a typical UPS responds in ~4 ms. Besides, the TEG will not necessarily protect against surges, so retaining a UPS for your sensitive electronics is still good practice.
Yep, on my list
 
If you do not have PWs, what turns off the PV in an outage?
The UL protocols 1741 control how an inverter behaves.

In the old days it was a strict 2 cycle response time for a 5 minute shutdown if the parameters were breached. Hawaii had a special problem here with long, low voltage fingers of the grid. This led to many tripped inverters that were near dirty power. Over the next 10 years with massive solar deployment and distributed ESS more finite control was needed.

The newer versions of 1741 Rule 21 protocols allow a certain voltage ride through where inverters don't shut down, depending on the interruption duration. They also allow frequency shifting to partially curtail the PV but not turn it all the way off.

So (I assume) older inverters like @h2ofun has are more likely to drop for 5 minutes, where newer inverters will have better behavior when the batteries are near full for instance. Some older inverters could perhaps have the firmware updated to be 1741 Rule 21 compliant.
 

holeydonut

Active Member
Supporting Member
Jun 27, 2020
3,088
2,440
East Bay NorCal
Yeah, there were a bunch of posts about UL1741 on the Enphase Enlighten forums a few months ago for the IQ7+. A lot of people were seeing some 5 minute shutdowns during the day and it was confusing since Enphase has gone big-corporate and stopped responding in their own forums.

But, a firmware update went out to the Enphase Envoys a few weeks ago, and the "problem" went away.

Edit: I don't want to crosspost to another forum here, but if you search Google you'll find there's literally only one thread with a lot of activity on Enphase's community site... and it's about UL1741 causing weird behavior to people all over the place. I'm always amazed at what @Vines knows about haha.
 
Last edited:

h2ofun

Active Member
Aug 11, 2020
3,618
867
auburn, ca
The UL protocols 1741 control how an inverter behaves.

In the old days it was a strict 2 cycle response time for a 5 minute shutdown if the parameters were breached. Hawaii had a special problem here with long, low voltage fingers of the grid. This led to many tripped inverters that were near dirty power. Over the next 10 years with massive solar deployment and distributed ESS more finite control was needed.

The newer versions of 1741 Rule 21 protocols allow a certain voltage ride through where inverters don't shut down, depending on the interruption duration. They also allow frequency shifting to partially curtail the PV but not turn it all the way off.

So (I assume) older inverters like @h2ofun has are more likely to drop for 5 minutes, where newer inverters will have better behavior when the batteries are near full for instance. Some older inverters could perhaps have the firmware updated to be 1741 Rule 21 compliant.
I have a brand new SE 11.4k, and an older SE 11.4K. Both had their fw fully current. They both acted the same way.
 
I have a brand new SE 11.4k, and an older SE 11.4K. Both had their fw fully current. They both acted the same way.

That makes sense as the blip you observed is directly due to the transfer time and power waveform phase change between the grid and PW powering your house. Not much to do with your solar inverters. As pointed by before, PW has to be powering your house before the grid glitch happens for you to see "seamless" transition. This is similar to the difference between line-interactive and online (double-conversion) UPS's. PW is a line-interactive and not online backup power source.
 
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h2ofun

Active Member
Aug 11, 2020
3,618
867
auburn, ca
That makes sense as the blip you observed is directly due to the transfer time between the grid and PW powering your house. Not much to do with your solar inverters. As pointed by before, PW has to be powering your house before the grid glitch happens for you to see "seamless" transition. This is similar to the difference between line-interactive and online (double-conversion) UPS's. PW is a line-interactive and not online backup power source.
So are you saying that for any power outage then, if the batteries are lets say on backup mode, so they are not charging the house, they may be a non seamless transition?
 

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