Tesla power wall in Tesla app. What am I really seeing?

[DonTom]

I recently had a Tesla Power Wall installed at my other house in Auburn, CA. 4 KW of solar.

What I cannot make sense of is when the solar is putting out more power, the app shows the house is using more power. Does this all the time. It can show the house as drawing 0.4 KW (400 watts ) as the sun comes up, solar supplying it all. Nothing shown from any other path coming or going (neither battery nor grid power). As the sun comes up a bit more, the solar panels put out 2 KW. Nothing is changing in the house (AFAIK) and then the house draws more than 1.5KW and then only 500 watts go back to the grid.

So does my house draw 400 or 1,500 watts when no real loads (not even a light on, compressors in refrigerator not running, etc).

What am I not seeing in the Tesla app? IOW, why would the house draw more just because the solar is putting out more power?

-Don- Reno, NV

 

[jgleigh]

Probably misconfigured CTs (current transformers). Unfortunately very typical on new installs.

 

[DonTom]

Probably misconfigured CTs (current transformers). Unfortunately very typical on new installs.

Does it affect anything other than my app?

How do they get misconfigured and what is the fix to get them configured correctly?

-Don- Reno, NV

 

[jjrandorin]

How do they get misconfigured

They are not installed correctly (wrong place in panel, wrong direction of powerflow, etc).

and what is the fix to get them configured correctly?

You contact the installer (or the company that installed them) to correct them after describing what you see.

 

[Matt-FL]

On my install, l see the 10% loss in the house usage versus inverter cost.

My house will show about 1.5kW higher than my Sense or Emporia says my house is using when I'm hitting 15kW solar. That seems to be because Tesla is accounting for the inverter wattage that is needed for the conversion.

I'm not sure why adding a battery would make that change appear though. This is how mine has worked since install (almost 2 years), and I figured it was as expected. I do like seeing the difference, as I can monitor the difference and potentially identify a coming issue.

 

[jgleigh]

On my install, l see the 10% loss in the house usage versus inverter cost.

Could you explain more and/or provide some pics? Normally that would mean something isn't being monitored correctly. 1.5kW is a lot.

 

[Matt-FL]

Here's May 2nd @ 11:45am. You can see the gradual increase in usage, as my solar ramps up.

This is my usage, I picked a spot prior to my AC or pool heat pump kicking in.

Here's my solar production at that time:

Comparing what sense saw for panel usage at about that time:

1411w at the panel, Tesla showing 2760w, difference of 1,349w. Roughly 10% of solar production @ 15,310w.

 

[h2ofun]

I recently had a Tesla Power Wall installed at my other house in Auburn, CA. 4 KW of solar.

What I cannot make sense of is when the solar is putting out more power, the app shows the house is using more power. Does this all the time. It can show the house as drawing 0.4 KW (400 watts ) as the sun comes up, solar supplying it all. Nothing shown from any other path coming or going (neither battery nor grid power). As the sun comes up a bit more, the solar panels put out 2 KW. Nothing is changing in the house (AFAIK) and then the house draws more than 1.5KW and then only 500 watts go back to the grid.

So does my house draw 400 or 1,500 watts when no real loads (not even a light on, compressors in refrigerator not running, etc).

What am I not seeing in the Tesla app? IOW, why would the house draw more just because the solar is putting out more power?

-Don- Reno, NV

Auburn, I live at Lake of the Pines, auburn

 

[DonTom]

Auburn, I live at Lake of the Pines, auburn

I have a ham radio buddy who lives there at Lake of the Pines, Mark, K6JJR on Camelia Way. My house is in Christian Valley in Auburn. I will be there in a couple of days.

-Don- Reno, NV

 

[DonTom]

On my install, l see the 10% loss in the house usage versus inverter cost.

My house will show about 1.5kW higher than my Sense or Emporia says my house is using when I'm hitting 15kW solar. That seems to be because Tesla is accounting for the inverter wattage that is needed for the conversion.

I'm not sure why adding a battery would make that change appear though. This is how mine has worked since install (almost 2 years), and I figured it was as expected. I do like seeing the difference, as I can monitor the difference and potentially identify a coming issue.

I would expect a small loss here and there, but not for the house to draw more power just because I have more solar power available to draw from. Other than that, it seems to be working normally.

-Don- Reno, NV

 

[jgleigh]

1411w at the panel, Tesla showing 2760w, difference of 1,349w. Roughly 10% of solar production @ 15,310w.

Looks like Sense solar reporting is off by the same 1.4kW. Might have to start doing current measurements in your electrical panels to see where the error is occuring.

 

[DonTom]

You contact the installer (or the company that installed them) to correct them after describing what you see.

I have the rented system from V3. I have not yet received my first bill from it. I figure 4KW is enough because I am there less than 50% of the time. But I own seven EVs to keep charged up (five are electric motorcycles, which I ride a lot). So my power usage goes from one extreme to the other at times.

I am going to add solar to this Reno house as well. But perhaps I will buy this system instead of renting it.

But I am NOT adding the solar to save money. I just like the idea. I would not consider a system without a battery. I do get power outages once in a while at each house. I like the way the Tesla Powerwall works and can be monitored in the same app as my Model 3. If the solar costs me a little more than I save, I am fine with that.

BTW, the electric PG&E KWH rate in Auburn is about three times what it is here in Reno with NV Energy. And here in Reno, I am on the top of a hill with a lot of sunlight--but the solar will just become a snow holder in winter. But I do get just above 4 KW out of my Auburn system at around noon and 22KWH per day added on most sunny days. Drops fast in the late afternoon, tall trees.

Is it normally better to buy or rent such a solar system? I am considering one of each, buying for here in Reno. The only reason I rented it in Auburn is V3 came to me first and talked me into it--perhaps they found their sucker. AFAIK, they only rent out the solar systems.

-Don- Reno, NV

 

[yblaser]

I would expect a small loss here and there, but not for the house to draw more power just because I have more solar power available to draw from. Other than that, it seems to be working normally.

-Don- Reno, NV

Just FYI, the house load is a calculated value. The Tesla app adds up the solar, PW, and grid flow and calculates an assumed house load. If one of those measurements (solar, PW, or grid) is off then the house load will be incorrect.

I have a similar issue as @Matt-FL but it looks like my system is reporting the solar production about ~7-8% high resulting in my house load reading a bit higher than it should during the day when solar is producing. The amount your system is off is quite large, so as others have said it could be an issue with a bad CT installation or configuration.

 

[h2ofun]

I have a ham radio buddy who lives there at Lake of the Pines, Mark, K6JJR on Camelia Way. My house is in Christian Valley in Auburn. I will be there in a couple of days.

-Don- Reno, NV

I just talked with Mark yesterday, so we know each other. Small world. I have 30kw of solar and 7 PW's. When I was talking to Mark yesterday he asked my opinion of buying solar and PW's. I said do not do it now with NEM3. But he said he could get them for free. I said o not do it. I gave him the link to this group and suggested he ask the question based on with sales folks are telling him and let the group give their opinions. Stop by and say Hi,

My dad, I and wife have ham licenses. I just put up some antenna's connected for my Dad to use his ham equipment we setup for him.
BUT, him being a ham for like 70 years, he is used to CQ with voice. This Ft8 stuff does not seem to interest him. Please he loved building stuff, ..

 

[h2ofun]

I have the rented system from V3. I have not yet received my first bill from it. I figure 4KW is enough because I am there less than 50% of the time. But I own seven EVs to keep charged up (five are electric motorcycles, which I ride a lot). So my power usage goes from one extreme to the other at times.

I am going to add solar to this Reno house as well. But perhaps I will buy this system instead of renting it.

But I am NOT adding the solar to save money. I just like the idea. I would not consider a system without a battery. I do get power outages once in a while at each house. I like the way the Tesla Powerwall works and can be monitored in the same app as my Model 3. If the solar costs me a little more than I save, I am fine with that.

BTW, the electric PG&E KWH rate in Auburn is about three times what it is here in Reno with NV Energy. And here in Reno, I am on the top of a hill with a lot of sunlight--but the solar will just become a snow holder in winter. But I do get just above 4 KW out of my Auburn system at around noon and 22KWH per day added on most sunny days. Drops fast in the late afternoon, tall trees.

Is it normally better to buy or rent such a solar system? I am considering one of each, buying for here in Reno. The only reason I rented it in Auburn is V3 came to me first and talked me into it--perhaps they found their sucker. AFAIK, they only rent out the solar systems.

-Don- Reno, NV

V3 put on some of my solar, and the PW's.

As I told Mark, I would never buy solar now, and new recommended PW's. But if one has money to burn, go for it.

With my setup, I have zero energy true with a huge surplus. I am basically off the grid for maybe at least 50% of the year.
I love having 5 EV charges in my garage, but only have one EV so far.

 

[DonTom]

The Tesla app adds up the solar, PW, and grid flow and calculates an assumed house load. If one of those measurements (solar, PW, or grid) is off then the house load will be incorrect.

I see this happen when the app says the house is running 100% from the solar. I guess that doesn't mean it really is. It shows steady after the sun is up and that is probably my real house draw.

Or is it?

What is a normal average house draw in KW for when everything possible is turned off? No lights on, etc. Average size house. Would it normally be closer to 1.5 KW or the 300 watts? I am just curious which is more likely to be the accurate one. Other than the two refrigerators, I cannot think of what could draw more than an amp or so combined, which would only be 120 watts when the refrigerator compressors are not running.

-Don- Reno, NV

 

[DonTom]

I just talked with Mark yesterday, so we know each other. Small world. I have 30kw of solar and 7 PW's. When I was talking to Mark yesterday he asked my opinion of buying solar and PW's. I said do not do it now with NEM3. But he said he could get them for free. I said o not do it. I gave him the link to this group and suggested he ask the question based on with sales folks are telling him and let the group give their opinions. Stop by and say Hi,

My dad, I and wife have ham licenses. I just put up some antenna's connected for my Dad to use his ham equipment we setup for him.
BUT, him being a ham for like 70 years, he is used to CQ with voice. This Ft8 stuff does not seem to interest him. Please he loved building stuff, ..

Yes, I noticed that in your signature line, you must have a large house there.

Mark and I are CW only operators.

I also have no interest in FT8.

Looks like there is a lawsuit over the NEM3 issue.

Perhaps that will soon go away.

73. -Don- AA6GA

 

[lodar]

Does it affect anything other than my app?

How do they get misconfigured and what is the fix to get them configured correctly?

Incorrectly setup CTs can be a really big problem! The Powerwalls do a very delicate balancing act and with the wrong CT data could put out the wrong power.

You should show the weirdness to whoever installed your system. They need to send a technician out to diagnose and fix it.

If you have a separate solar app and its output doesn’t match Tesla’s, then that would be a smoking gun. Also, if the AC frequency is really high like 62.5 Hz to 70 Hz, then your solar could be getting “curtailed”. This is normal if there is no grid connection and the batteries are full, but excess power should be getting dumped to the grid or charging the batteries.

There are some fail safes where the Gateway will trip the grid isolation breakers if there is obviously contradictory CT data. But other problems may not. Best to have your installer investigate.

 

[jgleigh]

What is a normal average house draw in KW for when everything possible is turned off? No lights on, etc. Average size house. Would it normally be closer to 1.5 KW or the 300 watts? I am just curious which is more likely to be the accurate one. Other than the two refrigerators, I cannot think of what could draw more than an amp or so combined, which would only be 120 watts when the refrigerator compressors are not running.

Every house is different. I have a larger house and at night it varies between 0.5-1kW. If everything is off and you're pulling 1.5kW, you're either missing something or the monitoring is confused.

 

[Matt-FL]

Looks like Sense solar reporting is off by the same 1.4kW. Might have to start doing current measurements in your electrical panels to see where the error is occuring.

Sense Solar CTs have always been off. The only way I could get them to work was reversing the polarity on one of the Sense CTs, and sense support washed their hands of supporting me when they knew I had batteries. I don't really pay attention to them TBH. I use sense for understanding my power use, and it is really good at capturing initial load spikes, like AC kicking off. Emporia is much more accurate, but it also normalized or has a much longer sensing time. It does not capture initial spikes.

It is the load I am most interested in comparing, and the sense house wattage is spot on with Emporia's. I view the difference as the inverter conversion cost, which is about spot on to what it should be.