Pre PTO, self powered, mode but still drawing from grid (Home consumption reported as half of real load)

[dev_lvl80]

I have brand new installed Solar 8.8KW + 2PWs. Pre PTO, self powered mode.
Apparently there is issue in installation and customer support gave me message, that system is self configuring (who knows ?!)
But here is the fact:

At this moment Solar Production:

car charging

That's quite not possible! House has some base consumption like 700w. Car is charging 16@240=3.6KW, But App reporting house consumption is half from that, Just 1.8KW !
Yesterday 8/30, I had self powered case 98%+, but my provider SCE reports, that I consumed from grid each hours. Which completely opposite to what

Powerwall reports 8/30:

South California Edison, hourly consumption from grid

Seems like PW track 50% of actual house load.

Additional facts:
- Car charger and AC are NOT backed up by power wall.
- Increase / Decrease amperage of car charge - proportionally ( from actual 50%) increase /decrease House usage on PW stats.

I fell my installation has an issue in wiring.... and self powered mode is not self powered mode now.
Thoughts ?

 

[jjrandorin]

Thoughts ?

That it is not at all unusual for non backed up loads to be invisible to the powerwall system. For them to be visible, a CT must be in place for the powerwall to see them (and the app to report on them). Its not automatic, and seems to depend on the the installer, and how difficult it is to monitor those non backed up loads due to the specific home power setup / panels, etc.

 

[dev_lvl80]

Thanks!

What is the CT ? I'm kind of newbie here
My assumption is that, if PW charged or Solar production is excessive, why should I pull from grid any Watt (not even KWh) ? Another things, it seems exact 50% of house load (not backed by PW) is missed from accounting.

 

[offandonagain]

CT is a current transformer and is used to measure the current of a circuit. In this case, it measures the grid import/export and uses that measurement in addition to a solar CT to compute the home usage (and adjust Powerwall discharge accordingly). It seems to be a common issue that CTs are installed or configured incorrectly. You should get your installer to verify.

One possibility is that your grid CT is only measuring one split phase, which would result in a ~50% underreporting of grid import (and thus 50% lower home load and inadequate Powerwall discharge).

 

[dev_lvl80]

CT is a current transformer and is used to measure the current of a circuit. In this case, it measures the grid import/export and uses that measurement in addition to a solar CT to compute the home usage (and adjust Powerwall discharge accordingly). It seems to be a common issue that CTs are installed or configured incorrectly. You should get your installer to verify.

One possibility is that your grid CT is only measuring one split phase, which would result in a ~50% underreporting of grid import (and thus 50% lower home load and inadequate Powerwall discharge).

Just got the same idea, thanks again !
Traced GW, it has CT1 & CT2, both wires go to old main panel. Haven't found where they plugged actually... but will try.

One possibility is that your grid CT is only measuring

Exactly.

PS how this is stupid, happy customer thinks he is self powered, but in fact far from that LOL

 

[dev_lvl80]

I found that CT1 reports negative readings, whereas CT2 positive.
For those who bump into such issue:
- connect to inverter (wifi TEG-) in installer mode
- run REST hit://<IP of inverter>/api/meters/readings

in my case first
CT1 reports
"instant_power": -2347,
"instant_reactive_power": 629,
"instant_apparent_power": 2429.825096586172,
"frequency": 0,
"energy_exported": 29767.594353720546,
"energy_imported": 12813.54000888258,
CT2:
"instant_power": 2569,
"instant_reactive_power": 2449,
"instant_apparent_power": 3549.2762642544467,
"frequency": 0,
"energy_exported": 3434.414663413192,
"energy_imported": 39615.957229414955,

in PRE PTO mode, there should not be negative consumption.

Hope I'm right in my troubleshooting

 

[jgleigh]

Can we see all your breaker panels? Where are the AC and EV charger breakers located?

The CTs are little black rings/donuts. They will be placed around wires in one of your other panels. Negative values are usually wrong unless you're exporting power.

 

[dev_lvl80]

Can we see all your breaker panels? Where are the AC and EV charger breakers located?

The CTs are little black rings/donuts. They will be placed around wires in one of your other panels. Negative values are usually wrong unless you're exporting power.

Thanks!

I opened breaker panel, and discovered what's wrong....
Tesla installed 4CTs only as:
2 CTs for backed load (right)
1 CT for AC (for 1 hot wire)
1 CT for Tesla Charger (for 1 hot wire)

did they have shortage of CTs ?! it's $15 part. lol

That's why I saw 50% load for non backed load and pulled from grid...
PS scheduled service appointment for EOM.

 

[BGbreeder]

Thanks!

I opened breaker panel, and discovered what's wrong....
Tesla installed 4CTs only as:
2 CTs for backed load (right)
1 CT for AC (for 1 hot wire)
1 CT for Tesla Charger (for 1 hot wire)

did they have shortage of CTs ?! it's $15 part. lol

That's why I saw 50% load for non backed load and pulled from grid...
PS scheduled service appointment for EOM.

They probably forgot to set the AC CT to be doubled in software. (and perhaps also for the Tesla charger?) It is an easy fix in software, and I think that it can be done remotely.

 

[taphil]

For GW, you can log in as installer and for each CT there's a checkbox option to 2x the CTs on the 240V circuits.

 

[dev_lvl80]

I think today is a day when everything works end to end! super happy to stop drawing energy from grid.
So, tesla service is awful, nothing new... They scheduled service for 9/29 (month from claim date)
During city inspection, 2 days ago, I complained to tesla representative on this issue. He seems local guy and know where installation teams deployed. He promised that one team could come early morning before they job site.
Indeed, installation teams are different level of service. Guys come troubleshooted and fixed issue.
As for issue itself, it was wrong wiring for CTs, they replaced wires and reverted "flipped CT". Everything works now like a charm.

 

[vincestanley]

Great discussion. Q. Where did you get the Powerwall Power Flow chart? LOVE IT!

 

[vincestanley]

I found this. Is this the site where you got it?
Not familiar with how all this works but can figure it out if it’s worth it. Did you install on a standalone computer? Thanks!!!