Tesla app vs Utility meter

[billarnett]

I’m getting inconsistencies between what the Tesla app reports and what my utility’s meter reports for both power and energy use. Tesla’s numbers are consistently about 20-25% higher. The correlation is perfect at all power levels. I even went so far as to measure the current going in to the utility with a clamp meter. Those measurements were much closer to Tesla’s than the utility’s. Is is really possible that my utility meter is wrong???

 

[devachnid]

I've found the same issue - Tesla app recording around 30% higher than utility meter:

I've seen a few threads about people with a similar meter to me reporting the opposite problem (meter reading higher than Tesla app), which seems to be due to power factors.

 

[miimura]

Really? You're complaining that the utility may be under-billing you? If you were a net exporter, I would see the problem, but if you are still a net consumer and the meter is registering fewer kWh, I would just count my blessings.

 

[BrettS]

Really? You're complaining that the utility may be under-billing you? If you were a net exporter, I would see the problem, but if you are still a net consumer and the meter is registering fewer kWh, I would just count my blessings.

I don’t think he’s complaining. The OP said that his tesla app and his utility had a discrepancy and @devachnid was simply saying that he also saw a discrepancy between his utility and his tesla app. It can be beneficial to see if this is a common problem or not.

For what it’s worth, I’ve only had my system set up for a little over a month, but on my first bill my tesla app reported that I used 416kWh from the grid and the utility reported 419kWh. That’s certainly close enough for me.

 

[devachnid]

Really? You're complaining that the utility may be under-billing you? If you were a net exporter, I would see the problem, but if you are still a net consumer and the meter is registering fewer kWh, I would just count my blessings.

I have no reason to believe the utility meter is wrong (it's only 1 year old), it's the readings in the Tesla app I'm suspicious about!

We don't have net billing in the UK, import and export is metered and billed separately (single meter but it has two registers - one for import, one for export)

 

[charlesj]

I have no reason to believe the utility meter is wrong (it's only 1 year old), it's the readings in the Tesla app I'm suspicious about!

We don't have net billing in the UK, import and export is metered and billed separately (single meter but it has two registers - one for import, one for export)

Utility meters are a revenue device and must be very accurate like scales, gas pumps, etc. Or, they would be cheting customers
Your utility may check the accuracy if a complaint is filed.

 

[powerWall-E]

I've found the same issue - Tesla app recording around 30% higher than utility meter:
View attachment 571616

I've seen a few threads about people with a similar meter to me reporting the opposite problem (meter reading higher than Tesla app), which seems to be due to power factors.

Have you got a gateway 2 and three-phase electric power? Tesla app (energy statistics but not in graphics) distinguishes between supply on different phases but your utility meter might net simultaneous feed-in and supply on different phases.

 

[devachnid]

Have you got a gateway 2 and three-phase electric power? Tesla app (energy statistics but not in graphics) distinguishes between supply on different phases but your utility meter might net simultaneous feed-in and supply on different phases.

Yes it's the Gateway 2 but only single phase power supply. Not sure about @billarnett 's situation though.

 

[powerWall-E]

Well, here in Germany we have three-phase power by default. But I only got one powerwall and if I need electric power in the late evening on another phase than that of my powerwall, the powerwall feeds-in energy to the grid on its phase and I simultaneously draw energy on the other phases. This results in no net energy supply for my utility meter but the gateway2 counts this as an energy feed-in and a draw. This results in about 15-30% (depending on PV-production) wrong grid import/export numbers. So I thought out problems might be related.

Here are some screenhots documenting my 3-phase problem with gateway 2:

In the app diagram (graphics) you can see that there's (almost) no exterior power supply from the grid but the gateway counts about 2 kWh. In addition I only fed-in about 32,3 kWh to the grid (as the utility meter reports) but the gateway registered 34,3 kWh (because of the 2 kWh that got moved to other phases). This results in an not so well percentage in the self-powered chart ("Eigenversorgung" in German). I only got 81% here where almost 100% would be correct from my perspective.

You can also see this problem in this video from UK

(about 6:40) although the author (Robert) is not aware of this (and he got 2 Powerwalls 2 so just one phase of his is not covered).

 

[Mosby]

I’m getting inconsistencies between what the Tesla app reports and what my utility’s meter reports for both power and energy use. Tesla’s numbers are consistently about 20-25% higher. The correlation is perfect at all power levels. I even went so far as to measure the current going in to the utility with a clamp meter. Those measurements were much closer to Tesla’s than the utility’s. Is is really possible that my utility meter is wrong???

Same issue here in Virginia with Dominion electric. Weirdly, I found that for several months they were really close to each other (I expect there to be some variance based on interval), but over the past five months the variance has grown to hundreds of kWh in some months. I'm having the utility come out and run a check on the meter, but I'm guessing that's not going to get me too far. Really tough to find experts at the utilities who can explain what may be causing this. You have to go through layers of folks who insist on telling you, "You know, we can't see your usage behind the meter, right?"

 

[billarnett]

After literally weeks of investigation by several guys from the utility (PG&E) I finally figured out what was wrong. There was a short between the input to my meter and the output from it to my breaker box. So some of the current from the utility was flowing directly to my house without being metered. It almost certainly was that way since my house was built 25 years ago. (I’m not sure and I don’t care whose fault it was, PG&E or the electrical contractor; it certainly wasn’t me The fix was easy enough. And now Tesla’s app agrees with PG&E’s meter.

 

[Mosby]

We had a great crew from Dominion Net Metering come out and test. First time they've tried to test a customer's production via a bidirectional meter. It was kind of cool to see that at least as they tested things the Tesla app agreed with what their testing equipment was pulling almost perfectly. I'm now starting to wonder if, because they do manual meter readings for our bidirectional meter, we literally had a meter reader who was reading the codes backwards and counting our production as consumption. It's fun to be at the cutting edge of this type of thing, but also slightly terrifying because it was clear that they are figuring it out as they go along.