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Powerwall 2: Technical

Ulmo

Active Member
Jan 19, 2016
4,329
4,905
Vienna Woods, Aptos, California
Has anyone else experienced this? Does anybody know what the reset button does? My PowerWalls are stuck in this mode; the app says 15% reserve, but they're behaving as if they have 90% reserve, still, after another full day.
 

Ulmo

Active Member
Jan 19, 2016
4,329
4,905
Vienna Woods, Aptos, California
I set the reserve to 10%, and at 1:33AM, they started behaving again. The Tesla App is buggy: it will fail to set the reserve very often, and sometimes, it doesn't know this, and thinks it set the reserve, but didn't, and then the pack doesn't operate properly. Bad programming to begin with: it shouldn't show false status.
 
  • Informative
Reactions: neroden

stevemcsheen

Member
May 16, 2017
12
4
Oakland, CA
Ullmo, I am having a related issue, I think. PW2 Firmware version 1.9.0, app version 3.2.0. What I experienced 2 nights in a row:

• Even though app was set to Backup-only overnight (I manually change it anywhere from 11pm-7am depending on if I wake up in the middle of the night or stay up late) the PW2 would not charge from the grid. This happened 2 nights in a row.

• I set it to Backup-only then tried going back to Self-powered and back again later in the day. Nothing I do changes its behavior. It will charge from solar but not from the grid. Changing the setting, quitting the app and restarting, trying on a different device - nothing works.

• I’m on PG&E in Oakland and I assume you’re PG&E too in Aptos?

I emailed Tesla Support yesterday morning but may have had the wrong email. Just now I emailed powerwallsupportNA at tesla dot com - previously I emailed the same address with no NA. They’ve responded quickly to the NA email in the past. I’ll let you know if they respond later today.

Joe

I set the reserve to 10%, and at 1:33AM, they started behaving again. The Tesla App is buggy: it will fail to set the reserve very often, and sometimes, it doesn't know this, and thinks it set the reserve, but didn't, and then the pack doesn't operate properly. Bad programming to begin with: it shouldn't show false status.
 

commasign

TeslaAdviceBlog.com
Aug 31, 2013
3,202
4,290
Davis, CA
Some bugs they still need to work out. ;)

235DF492-C73B-4CD9-AE98-BC4B8157AA5C.png
E38D30A6-CDAD-4071-9FDD-FEAB5A4B9169.png
 
  • Funny
Reactions: Shygar and abasile

Icepicknz

Member
May 19, 2018
47
6
Auckland new zealand
Actually from the data @Ulmo has posted, it seems that the Powerwall may be doing something much smarter than the Sonnen. Sonnen just trips the inverter by going to 60.9 Hz. Tesla is doing slow ramp to 60.5 Hz which is the UL 1741 spec to trigger conventional (all-on/all-off) inverters, then a ramp to max 63 Hz which would take advantage of power throttling. We know that the Gateway can measure the instantaneous solar power so that should be a closed-loop ramp of frequency, but people here will confirm that with power-throttling inverters soon (SolarEdge, SMA, or Schneider). We at least know the Powerwall can shift frequency by 3 Hz which captures the typical frequency-shift window which sits 1 Hz above nominal frequency. Not clear if Sonnen can shift above 0.9 Hz, and do it with a closed loop, which would be required for power control. To be fair, there should be an option now for you to tell the Powerwall you don't have a throttling inverter connected, so that it restricts its frequency shift to a minimum range necessary to turn off inverters. However we now have a new spec called UL 1741 SA required in California which builds in this power-throttling capability for the "smart grid." It seems Tesla is capable of meeting this new spec and maybe already does, while the specs posted by Sonnen indicate it cannot (there is also a technical comment to your posted article pointing this out).

Sorry to be reviving such an old post, but i found it by chance and the only one i could find to do with ramp of frequency. Do you know of anything new in this space? I have a single power wall 2 and 5.7kw of solar on the roof (SolarEdge HD5000) which supports Power Frequency gradient reduction of production. I'm looking at adding a second 5.7kw of Solar X1 Boost which does not support any frequency ramp from what i can find.

What I'm wondering, the single power wall can support 7.8kw of charge at any point, during grid tied connection it will export any excess, however if i was producing max power output from the solar and a grid disconnect occurred, my solar would reboot and wake after 60 seconds, however how quickly will the Tesla tell the Solar to ramp down (even if battery was not full) due to the inverter receiving too much energy? would it at all? I know the SolarEdge would ramp down if it were told and the Solax would just cease to generate power if the frequency was too high; but i'm just wondering if the Powerwall will modify its frequency due to too much solar generation?

There is a video at
which shows a graph (8 mins 10 seconds in) of the frequency gradient due to the power wall getting near full, I just wonder what that would look like during a grid cut when solar is starting to generate too much energy for the power wall inverter to handle.
 

mongo

Well-Known Member
May 3, 2017
13,470
42,098
Michigan
Sorry to be reviving such an old post, but i found it by chance and the only one i could find to do with ramp of frequency. Do you know of anything new in this space? I have a single power wall 2 and 5.7kw of solar on the roof (SolarEdge HD5000) which supports Power Frequency gradient reduction of production. I'm looking at adding a second 5.7kw of Solar X1 Boost which does not support any frequency ramp from what i can find.

What I'm wondering, the single power wall can support 7.8kw of charge at any point, during grid tied connection it will export any excess, however if i was producing max power output from the solar and a grid disconnect occurred, my solar would reboot and wake after 60 seconds, however how quickly will the Tesla tell the Solar to ramp down (even if battery was not full) due to the inverter receiving too much energy? would it at all? I know the SolarEdge would ramp down if it were told and the Solax would just cease to generate power if the frequency was too high; but i'm just wondering if the Powerwall will modify its frequency due to too much solar generation?

There is a video at
which shows a graph (8 mins 10 seconds in) of the frequency gradient due to the power wall getting near full, I just wonder what that would look like during a grid cut when solar is starting to generate too much energy for the power wall inverter to handle.

Not a PW tech, so take with a grain of salt:

The PW charger / inverter-in-reverse operates independently of the solar power output. If the battery is full, it will not charge it further. So the case is not the inverter receiving too much energy, but rather the line voltage going too high from the excess solar output. The solar inverters will have their own cut offs for line over voltage also.

If the system is running in grid disconnect mode, the output frequency should always be adjusting based on the battery SOC and line voltage. So to your question, fairly instantaneously.

I'm curious: Why would your solar reboot when disconnecting from the grid?
 

en97

New Member
Aug 16, 2018
4
0
US
Does the gateway disconnect grid neutral as well as both lines?

Anyone have pictures of the relay / contactor in the gateway?
 

en97

New Member
Aug 16, 2018
4
0
US
Based on the pictures from some forum members:

IMG_8172 inside overview.png IMG_8549a-powerwall2-gateway.jpg

Think I found it...

BST 902-2X-200A/240V AC 12V DC Latching Relay

s-l1600-BST 902-2X-200A 240V AC 12V DC Latching Relay.jpg s-l1600-BST 902-2X-200A 240V AC 12V DC Latching Relay.jpg

or a custom design based on this.
 

en97

New Member
Aug 16, 2018
4
0
US
The gateway does not switch the neutral. There is a neutral bar in the gateway that all neutral conductors land on.

Cheers, Wayne

Thanks for the info. Thats what it looks like from the pictures - my intuition says the system should completely disconnect from grid in a power outage because in a short situation some current can return via neutral.

Or does the ground and neutral tie-in in the main breaker box prevent that scenario? So no current goes to grid neutral when in a micro grid backup scenario.
 

mongo

Well-Known Member
May 3, 2017
13,470
42,098
Michigan
Thanks for the info. Thats what it looks like from the pictures - my intuition says the system should completely disconnect from grid in a power outage because in a short situation some current can return via neutral.

Or does the ground and neutral tie-in in the main breaker box prevent that scenario? So no current goes to grid neutral when in a micro grid backup scenario.

The power company transformer only has two hot phases and neutral. Neutral becomes earth ground at the main service entry via the ground rod and bonding clamps. If you remove both phases, there is no longer any circuit for current to flow through.

You may be thinking of a generator set up where the generator may be earthed separately with neutral and ground connected (generator as sole power source). In that case, the neutral should also be switched when changing power sources. (You do not want two neutral/ground connection points)

Solar/ powerwall do not bond neutral to ground, so no issue there.

(There is one case where you could get current on the neutral during island mode, but it requires two faults, a specific transformer set up, is low current, and only impacts your local service)
 

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