Constant Grid Power Usage Despite plenty of Solar and/or Powerwall Power to cover home load

[Oz-X]

System Details

1. 800A power service from the grid that is split to 4 200A panels that feed the house.
2. 61 solar panels managed by 2 Solaredge 11.4 kWh inverters
3. Tesla Gateway and 4 Tesla 2 Powerwalls
4. System setup to provide power to the entire house but with only 1 panel backed up / used for grid power outage times

Problem: Regardless of time day, Tesla Gateway mode (Time based OR Self-Powered), amount of Solar production, or amount of home load, there is constant grid power usage despite plenty of Solar and/or Powerwall power.

The constant power draw ranges from .5 to 1.5 kWh hourly all day. This draw is present even if the 4 Powerwalls are 100% full and the home load is only 3.5 kWh! You can see from the grid power screenshot it never goes to 0 during the day. (I'm on an EV power plan that's least expensive from 11pm to 7am so I try to use grid power during this time when necessary)

The only time the Tesla app shows I'm not using grid power is when there is solar excess. I'd always try to have excess but my utility company doesn't give me any credits because my system is "too large".

I'm getting the run around from Tesla PW Support and no way to escalate.

Thoughts?

 

[Matt-FL]

What is your Powerwall reserve set to?

Unless they are set at 100%, they should be providing power to the house. It would appear that it is acting like reserve is set at 100%, as you see the grid usage reduce once the sun comes out. However, it should reduce to zero, unless your house is using more than solar is providing.

However, from your first screenshot, your PWs are only at 30% which means you have (most likely) reserve set to 20%. Definitely something is amiss.

Here's what mine looks like, I've got my reserve set to 20%:

 

[Oz-X]

Reserve is set to 0%! We hardly ever lose power so my sole purpose of the system is to not rely on the grid.

Exactly, I'm expecting my grid home usage to be 0% when solar and/or powerwalls have more than enough power to cover the home load. That never happens for me. Grid usage is always at least .5 to 1.5 kWh unless I'm exporting excess solar (PW's @ 100% and solar is above home load).

 

[Matt-FL]

Could it be that the load CTs are pulling wattage from the other non-backed-up panel(s)?

Your first screenshot is not showing you pulling from the grid, but your second screenshot is showing you are. I'm thinking a CT placement issue possibly.

 

[Vines]

System Details

1. 800A power service from the grid that is split to 4 200A panels that feed the house.
2. 61 solar panels managed by 2 Solaredge 11.4 kWh inverters
3. Tesla Gateway and 4 Tesla 2 Powerwalls
4. System setup to provide power to the entire house but with only 1 panel backed up / used for grid power outage times

Problem: Regardless of time day, Tesla Gateway mode (Time based OR Self-Powered), amount of Solar production, or amount of home load, there is constant grid power usage despite plenty of Solar and/or Powerwall power.

The constant power draw ranges from .5 to 1.5 kWh hourly all day. This draw is present even if the 4 Powerwalls are 100% full and the home load is only 3.5 kWh! You can see from the grid power screenshot it never goes to 0 during the day. (I'm on an EV power plan that's least expensive from 11pm to 7am so I try to use grid power during this time when necessary)

The only time the Tesla app shows I'm not using grid power is when there is solar excess. I'd always try to have excess but my utility company doesn't give me any credits because my system is "too large".

I'm getting the run around from Tesla PW Support and no way to escalate.

Thoughts?

Problems like this are often issues with the CT meters. I would suspect that one of them (likely solar generation) is not accurate.

This can be due to a discrepancy between voltage source to the neurio and the point of measurement, incorrect voltage reference leg or an internal issue with the neurio.

If both Solar Edge inverters are online, I would compare real time output numbers between those sources compared with the reported generation within the app.

Some of the CT meters are more accurate than others, so it may be that the CT's themselves need to be swapped out for a different type or another meter with better accuracy. It might be as well that the pv meter has the incorrect reference leg for voltage sense. Do you know the following?

Whether the PV is monitored by plug in 100A CT's or Neurio 200A CTs?

Distance from the Gateway to the PV monitoring location?

 

[Vines]

Reserve is set to 0%! We hardly ever lose power so my sole purpose of the system is to not rely on the grid.

Exactly, I'm expecting my grid home usage to be 0% when solar and/or powerwalls have more than enough power to cover the home load. That never happens for me. Grid usage is always at least .5 to 1.5 kWh unless I'm exporting excess solar (PW's @ 100% and solar is above home load).

Does this measurement error of the home load increase with the PV generation at midday? So it would be more like 1 kw at night and 1.5 kW during the day?

 

[Oz-X]

Does this measurement error of the home load increase with the PV generation at midday? So it would be more like 1 kw at night and 1.5 kW during the day?

Yes from ~.4 up to ~1.5 kWh or so daily.

 

[Vines]

Yes from ~.4 up to ~1.5 kWh or so daily.

Then the CT error is almost certainly the issue. Confirm your PV generation with Solar Edge or even with an amp meter and compare it to what the app says. My bet is you will be about 1 kW off.

 

[Oz-X]

Problems like this are often issues with the CT meters. I would suspect that one of them (likely solar generation) is not accurate.

This can be due to a discrepancy between voltage source to the neurio and the point of measurement, incorrect voltage reference leg or an internal issue with the neurio.

If both Solar Edge inverters are online, I would compare real time output numbers between those sources compared with the reported generation within the app.

Some of the CT meters are more accurate than others, so it may be that the CT's themselves need to be swapped out for a different type or another meter with better accuracy. It might be as well that the pv meter has the incorrect reference leg for voltage sense. Do you know the following?

Whether the PV is monitored by plug in 100A CT's or Neurio 200A CTs?

Distance from the Gateway to the PV monitoring location?

Thanks for the reply.

To me it has to be either CT config issue, Gateway problem, and/or Tesla software issue. The installer (Alternative Energy Southeast AES) did make a CT change months ago. It worked great for about 2 months and then back to leakage and inaccurate reporting.

I'm gaining clarity as to the CT type and location with the last change. I know they moved the CT's to the main 800A utility box to try and reduce the overall number of CTs the gateway had to manage. I'll post up a quick system diagram once I get that info.

I'm pretty sure I'm still using Neurio's.

Very short distance from gateway to everything. image attached.

 

[Oz-X]

Then the CT error is almost certainly the issue. Confirm your PV generation with Solar Edge or even with an amp meter and compare it to what the app says. My bet is you will be about 1 kW off.

I have a voltage/amp meter but not sure how I'd do that. just connect it to the downstream legs? Also, in the physical panel to inverter layout, there is a few more panels on 1 inverter than the other. this image shows that with the different power draws from each.

 

[Vines]

I have a voltage/amp meter but not sure how I'd do that. just connect it to the downstream legs? Also, in the physical panel to inverter layout, there is a few more panels on 1 inverter than the other. this image shows that with the different power draws from each.

I would measure the downstream legs of the combined feed from the 2 inverters to get the most accurate measurement.

As a plan B, you could measure each inverter individually, then add them together.

Then take the amperage reading and multiply it by the voltage, this will give you instant power, which you can cross-reference with your app.

Sounds like you need to call your installer back out and get them to fix the monitoring. If you do go off the grid, I wonder if your readings will show correctly?

 

[Vines]

Thanks for the reply.

To me it has to be either CT config issue, Gateway problem, and/or Tesla software issue. The installer (Alternative Energy Southeast AES) did make a CT change months ago. It worked great for about 2 months and then back to leakage and inaccurate reporting.

I'm gaining clarity as to the CT type and location with the last change. I know they moved the CT's to the main 800A utility box to try and reduce the overall number of CTs the gateway had to manage. I'll post up a quick system diagram once I get that info.

I'm pretty sure I'm still using Neurio's.

Very short distance from gateway to everything. image attached.

At the top left is your insant power.

 

[Oz-X]

The difference in Solaredge production and Tesla reported solar production is right at the amount of grid power leakage/usage i'm seeing.

 

[Oz-X]

I can't go off grid via the app because that will allow utility power to flow through to the other 3 non-back up panels.

I did flip the breakers on all 4 sub panels and the utility usage did go to 0 as expected.

 

[Oz-X]

I agree this must be a Tesla / CT issue of not accurately calculating home power needs and/or Solar generation amounts.

 

[Oz-X]

Tesla gateway

 

[Vines]

The difference in Solaredge production and Tesla reported solar production is right at the amount of grid power leakage/usage i'm seeing.

View attachment 1021202

View attachment 1021203

Sounds like you figured out the issue. Now get your installer on the phone to discuss any possible resolution.

 

[Oz-X]

Trying. They’ve blamed Tesla so far and waiting on tier 2 to advise them.

 

[Oz-X]

Installer (AES) came out today.

Verified main power CT locations and direction

Verified solar generation CT location and direction

At Tesla’s request, they took a video of everything and sent it to them for review and next steps.

 

[Oz-X]

Installer put in a new neurio in October. The system the. worked great with no grid power leakage for about a month. That power bill was the lowest I had seen ever.
Then the power leakage started happening.

I’m now betting it’s the neurio again or some strange software pushed to it.