Tesla production numbers doesn't match PG&E...

[Imolared]

System activated last month, just got my PG&E statement, bill range is from September 15 through October 14th.

Consumption 623.30 kWh
Net generation shows 525.62 kWh
Net usage: 97.68 kWh

Tesla's number from the app when I added the date range above: 829.8 kWh

Who do I dispute this with or am I missing something?:

 

[GHammer]

Net generation to the utility is minus what your house used. So your house used about 300 kWh and the excess 525 was sent back to the utility.

 

[Mosby]

I'm with you. I have had a very similar system installed, about 8 kW. We are on the east coast, and actually have a slightly different situation with our utility in that they weren't showing us how much we were putting into the grid on our bill. They just showed us as net consumers, vice net producers. This conflicts with what our Tesla app was telling us, which showed us putting about 20% more back into the grid than we were consuming from the grid on a monthly basis. So I disagree with GHammer on this one, because if I am understanding your post correctly, you should still be net positive (ie-putting more back into the grid than you pull from the grid for that period).

In my case I contacted our utility provider (Dominion) to ask what they saw as far as how much we were putting back into the grid. The crazy thing was that THEY COULD NOT TELL ME. They had been billing me as a net meter customer but explained that they had no idea how much I was putting back into the grid. I continue to be baffled by this response. However, in my case, they offered to put in an improved meter which would allow for better monitoring (again, I am not sure how the previous bi-directional meter did not provide granular data on power put back into the grid).

But back to your situation-I recommend contacting the utility and asking about the discrepancy to see what they say. Now that we have a better meter, I'll be interested if we see a discrepancy between what our Tesla app says we are putting back into the grid and what the utility registers us as having put back into the grid.

 

[r0xx0r]

The Utility meter can’t count your house internal usage.
Example in the morning/solar time: your system generated 1000kWh, and your house used 500kWh for that month. So total went out to the grid during the daytime +500kWh.
But during night time/solar off for that month, you used 600kWh total. So -600kWh.

Based on that, the utility bill will show that total usage: 600kWh, generated 500kWh, net usage: 100kWh.

But for your internal app meter: it will show total usage 1100kWh.

 

[GHammer]

Sorry, I dont have a Tesla system and was unaware it had insight into the house/grid split; mine doesn't. Please disregard.

 

[BrettS]

@Mosby, some meters just have one number. When you take power from the grid the number goes up and when you send power to the grid the number goes down. So the utility is able to tell what your net usage (or production) was, but it doesn’t keep track of usage and production separately so they can’t tell you that you pulled x amount from the grid and you fed y amount into the grid.

 

[wjgjr]

@Mosby, some meters just have one number. When you take power from the grid the number goes up and when you send power to the grid the number goes down. So the utility is able to tell what your net usage (or production) was, but it doesn’t keep track of usage and production separately so they can’t tell you that you pulled x amount from the grid and you fed y amount into the grid.

This is our situation, and it results in what I can only describe as "weird" numbers from our utility. Essentially, it seems to take every hour and, if it is negative, treat it as generation, and if it is positive, treat it as use. As an example, last month, our bill claims our "Use" was 381 kWh and "Excess Generation" was 391 kWh. In reality, our generation was about 610 kWh and usage 600 kWh. I'm not sure if this is what is happening for OP.

The easiest way to compare to your utility bill would be to sum up the to and from grid numbers in the app and see how the net of those matches to your utility. If, as I understand it, net usage for the month was 98 kWh, then from grid less to grid should roughly equal that.

 

[Imolared]

The Tesla app only shows me the 1 number which I believe is the total produced for the day. Sample day report from PG&E website, and the daily breakdown between what the app and PGE says.

 

[Imolared]

This is what the app show for the day.

 

[Mosby]

This is our situation, and it results in what I can only describe as "weird" numbers from our utility. Essentially, it seems to take every hour and, if it is negative, treat it as generation, and if it is positive, treat it as use. As an example, last month, our bill claims our "Use" was 381 kWh and "Excess Generation" was 391 kWh. In reality, our generation was about 610 kWh and usage 600 kWh. I'm not sure if this is what is happening for OP.

The easiest way to compare to your utility bill would be to sum up the to and from grid numbers in the app and see how the net of those matches to your utility. If, as I understand it, net usage for the month was 98 kWh, then from grid less to grid should roughly equal that.

Thanks, @BrettS and @wjgjr. It was very interesting to me that when I called Dominion, after about 15 minutes of back and forth, they offered to replace our meter with one which provides more insight. It was like they had a flowchart that said "if customer clearly realizes that we can't effectively net meter using their current meter, offer to replace it with the new meter." I will be interested to see what the data from the new meter provides compared to the Tesla app.

 

[Mosby]

This is what the app show for the day.
View attachment 601897

Does your Tesla app have the To/From Grid icon (looks like a power line)? That's what I use when it comes to understanding whether I am a net producer or consumer and all the other stuff (usage, solar production) then isn't part of the equation.

 

[wjgjr]

Thanks, @BrettS and @wjgjr. It was very interesting to me that when I called Dominion, after about 15 minutes of back and forth, they offered to replace our meter with one which provides more insight. It was like they had a flowchart that said "if customer clearly realizes that we can't effectively net meter using their current meter, offer to replace it with the new meter." I will be interested to see what the data from the new meter provides compared to the Tesla app.

Hopefully it will help get you better data, though, depending on where the meter is located, it can only do so much. As I mentioned, our utility comes up with some weird numbers, which I think just make things more confusing in the way they report them. But even if they added a meter that measured inflow and outflow separately and instantaneously, they couldn't give us our true production and consumption because of where the meter is located relative to our solar - they have no way to track how much of our solar is being directed to our home/PWs.

 

[BrettS]

Thanks, @BrettS and @wjgjr. It was very interesting to me that when I called Dominion, after about 15 minutes of back and forth, they offered to replace our meter with one which provides more insight. It was like they had a flowchart that said "if customer clearly realizes that we can't effectively net meter using their current meter, offer to replace it with the new meter." I will be interested to see what the data from the new meter provides compared to the Tesla app.

They can absolutely effectively net meter with the current meter. Net metering simply means that you pay for the power that you use minus the power the you produce. That is what’s happening with your current meter... when you use power the number counts forward and when you produce power it moves backwards. And if you compare the reading at the end of the month to the reading at the end of the previous month you know what your net usage of power that month is.

Many utilities have smart meters that keep two running totals... one total of how much you used and on total of how much power you produced. Obviously with a meter like that it’s easier to see how much power you are pulling from the grid and how much power you are feeding into the grid, but at the end of the month they compare the readings to the previous month and then subtract the amount of power that you produced from the amount of power that you used and will come up with the exact same number that the other type of meter provided, and that’s what you’re billed on.

It’s not a matter of being unable to effectively net meter or having bad data. Like they said, the meter swap will just provide more insight and additional data that the other meter can’t provide that might be helpful for you.

 

[BrettS]

The Tesla app only shows me the 1 number which I believe is the total produced for the day. Sample day report from PG&E website, and the daily breakdown between what the app and PGE says.

Like the others said, you’re kind of comparing apples to oranges here. The number provided by your Tesla app is not measuring the same thing as the number provided by PGE.

The Tesla app is showing you the total amount of power that your solar system produced. However some of that power is used directly by your house during the day when the power is produced. PGE can only see the amount of power that your system feeds back into the grid or pulls from the grid. It won’t see (or give you credit for) power that your system produced that was used directly by your house.

For example. Say from noon to 1pm your solar system produced 5kWh of energy, but during that same time your house used 2kWh of energy. In that case your Tesla app would have added the full 5kWh that the system produced to its total. However PGE would have only added 3kWh to its total. Your system produced 5kWh, but your house used 2kWh, so there was 3kW of excess power that was fed to the grid. This is what PGE can see and what PGE counts.

The numbers that you see in the PGE bill will never match what you see in the Tesla app unless you turn everything in your house off so that it uses no power at all. At that point all the power you produce will be fed into the grid, so PGE will see all of it.

 

[Imolared]

Thanks BrettS - this makes sense now.

So technically, 829.8 kWh (Tesla number) + 97.68 net use according to PG&E = 927.48 is my total usage for the month.

This makes perfect sense since this is in line with our average monthly usage for the past year.

 

[BrettS]

Thanks BrettS - this makes sense now.

So technically, 829.8 kWh (Tesla number) + 97.68 net use according to PG&E = 927.48 is my total usage for the month.

This makes perfect sense since this is in line with our average monthly usage for the past year.

Yes, that’s correct.

On a side note, typically with a solar only install Tesla will install a device called a powerblaster. This can measure how much power you are taking from or sending to the grid and with that data and the production data from your inverter it can also figure out how much power your house uses. That will allow it to display all this data in the tesla app.

We have seen some installs where the powerblaster has been installed, but isn’t correctly associated with someone’s account, so that data doesn’t show up. We’ve also seen some installs where tesla didn’t install the powerblaster for some reason (occasionally there isn’t enough room in the panel or the panel is incompatible with it). But you may want to give tesla a call and ask why you can’t see this other data in your app. If you already have the powerblaster they may just need to make sure it’s registered correctly, or they may be able to come out and install the powerblaster if it will work for your system.

 

[Redhill_qik]

I have a PG&E Focus AXR-SD smart meter. The display cycles through a odometer like kWH reading, an instantaneous AC voltage reading and a instantaneous kw power reading. I don't have PTO yet, but when the system was being tested the power number was negative and my assumption is that the odometer kWh reading would decrease if the system was left on long enough.

My assumption is that all of PG&E smart meters have similar functionality, so you should be able to look at the Tesla app and your meter at the same time to see that the grid number matches the meter reading.

 

[JohnRatsey]

I would also note that not all meters produce the same readings as some folk in the UK have discovered Beware SMETS2 meters .

 

[Imolared]

We have seen some installs where the powerblaster has been installed, but isn’t correctly associated with someone’s account, so that data doesn’t show up.

I took this photo while the panels were open during the final inspection. Will need to get Tesla support to configure to my account.

 

[BrettS]

I took this photo while the panels were open during the final inspection. Will need to get Tesla support to configure to my account

That would definitely be a powerblaster in the upper left inside that panel, so you should be seeing your home power usage and the grid usage in your app. It has its own breaker in the upper right labeled powerblaster. I would first double check to make sure that the breaker is actually on. Maybe even turn it off and on again to try to reset the device, but if that doesn’t make a difference then call Tesla and ask them to fix it.