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My Powerwall is discharging to the Grid (App or Neurio issue or both?)

4us2bev

Member
Nov 17, 2014
45
2
Los Altos, CA
Two Powerwalls installed four days ago with Neurio monitor, Time-base control showed up shortly thereafter and I set it to Cost Savings with 20% reserve. Here in Northern California, Peak is 3p to 12 midnight, off-peak is 12 midnight to 3p.

My quiescent Household load ranges from 0.5 kW (fridge + vampire draw) to 1.4 kW (downstairs lights on); no A/C or other heavy loads are involved.

Seven screenshots below show:

* 12 noon -- Powerwall still being charged (all info accurate)
* 2:15p -- Powerwall @ 100%, but household load now reported to be 2.5 kW despite...
* PGE meter showing -3.67 kW being delivered back to Grid -- conclusion: Tesla App / Neurio thinks my Household load is 2.5 kW when it's really 0.6 kW; this delta of 1.9 kW when added to the + 1.8 kW reported as being sent back to Grid = 3.67 kW as shown by PGE meter
* 3p -- beginning of Peak and now Tesla App / Neurio think my Household load is 5.3 kW (!)
* PGE meter showing -8.22 kW being delivered back to Grid -- conclusion: Tesla App / Neurio are discharging 4.4 kW (8.22 kW actual less 3.8 kW reported) from my Powerwall back to the Grid. This should never happen, right? My Powerwall charge level starts plummeting.
* 4:38p -- I reset the circuit that the Neurio is on and while it's rebooting, draw from Powerwall stops and my Household load is revealed to be 1.4 kW
* 4:39p -- A few moments later when the Nuerio is up again, we see expected behavior: Powerwall sending 1.3 kW to my Household and all 3.8 kW Solar being sent back to Grid

I have begun a discussion with Tesla about this but would appreciate any insight from those more knowledgeable as to what is going on.

To my eye, some combination of Tesla App / Neurio is not only overstating my Household power draw once my Powerwall is charged, but also discharging Powerwall energy (thats spent all morning accumulating so I can run my Household after 3p) at an accelerated rate right back to the Grid. This is not only inefficient, but causes unnecessary cycling of the Powerwall and severely compromises my reserve in case of emergency.

Thanks in advance for any insight,
David
 

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4us2bev

Member
Nov 17, 2014
45
2
Los Altos, CA
The Tesla App screenshots don't show it, but the only way that the PGE meter shots make sense (to me) is if the PW is being discharged back to the Grid.

If you compare second and third screenshots, I think the app is incorrectly showing my Household load, and if you compare fourth and fifth screenshots, I think the app has magnified the Household load error and started discharging PW to Grid (even though the app doesn't show that).

But I would be happy if someone could come up with an alternative explanation!

David
 

power.saver

Supporting Member
Mar 4, 2018
564
578
Arcadia, CA
Two Powerwalls installed four days ago with Neurio monitor, Time-base control showed up shortly thereafter and I set it to Cost Savings with 20% reserve. Here in Northern California, Peak is 3p to 12 midnight, off-peak is 12 midnight to 3p.

My quiescent Household load ranges from 0.5 kW (fridge + vampire draw) to 1.4 kW (downstairs lights on); no A/C or other heavy loads are involved.

Seven screenshots below show:

* 12 noon -- Powerwall still being charged (all info accurate)
* 2:15p -- Powerwall @ 100%, but household load now reported to be 2.5 kW despite...
* PGE meter showing -3.67 kW being delivered back to Grid -- conclusion: Tesla App / Neurio thinks my Household load is 2.5 kW when it's really 0.6 kW; this delta of 1.9 kW when added to the + 1.8 kW reported as being sent back to Grid = 3.67 kW as shown by PGE meter
* 3p -- beginning of Peak and now Tesla App / Neurio think my Household load is 5.3 kW (!)
* PGE meter showing -8.22 kW being delivered back to Grid -- conclusion: Tesla App / Neurio are discharging 4.4 kW (8.22 kW actual less 3.8 kW reported) from my Powerwall back to the Grid. This should never happen, right? My Powerwall charge level starts plummeting.
* 4:38p -- I reset the circuit that the Neurio is on and while it's rebooting, draw from Powerwall stops and my Household load is revealed to be 1.4 kW
* 4:39p -- A few moments later when the Nuerio is up again, we see expected behavior: Powerwall sending 1.3 kW to my Household and all 3.8 kW Solar being sent back to Grid

I have begun a discussion with Tesla about this but would appreciate any insight from those more knowledgeable as to what is going on.

To my eye, some combination of Tesla App / Neurio is not only overstating my Household power draw once my Powerwall is charged, but also discharging Powerwall energy (thats spent all morning accumulating so I can run my Household after 3p) at an accelerated rate right back to the Grid. This is not only inefficient, but causes unnecessary cycling of the Powerwall and severely compromises my reserve in case of emergency.

Thanks in advance for any insight,
David
Yes, this should never happen. It constantly amazes me that Tesla can't get this right. Many customers have reported problems with the Nuerio sending incorrect data.

Eventually this is going to bite Tesla when a utility finds out a customer is exporting a lot of power into the grid. It's good that you noticed this and documented the discrepancy between the app and your electricity meter. I would send all this information to Tesla and demand that they fix the problem. The customer should not have to be powering off and resetting things just to keep their system working.
 

power.saver

Supporting Member
Mar 4, 2018
564
578
Arcadia, CA
I don't see any PW going back to the grid in your pics.
The system thinks the house is drawing more power that it actually is, so the PW discharges a larger amount than the house is using, and the result is an export to the grid. The app won't show this, only looking at the electricity meter reveals the problem.
 

h2ofun

Active Member
Aug 11, 2020
2,657
490
auburn, ca
The system thinks the house is drawing more power that it actually is, so the PW discharges a larger amount than the house is using, and the result is an export to the grid. The app won't show this, only looking at the electricity meter reveals the problem.
Why would he tell Tesla, he now has a undocumented feature
 

4us2bev

Member
Nov 17, 2014
45
2
Los Altos, CA
That's an interesting idea but it has taken me so long to triage and document the current behavior that I'm going to take a break from troubleshooting and see if Tesla comes back with anything helpful.

It is obviously beneficial to be charging my PW at 0.18 / kWh and then sending it right back to the Grid at 0.49 / kWh but as it stands, my usage data is all screwed up and my PW is unnecessarily cycling, so it seems like I should insist they correct this. And hopefully their proposed solution is not to remove my Neurio!

David
 

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