Another PG&E vs Tesla app data question

[seenhear]

I've read several threads here of people asking about why their Tesla data don't reconcile/agree with their PG&E data. I have the same question, and none of the other threads really seemed to apply to my situation.

I have a 8.6kW Tesla system with 2x powerwalls. I typically see peak production power in the summer months of around 5.5-6kW.

My Tesla app data and downloaded PG&E data never agree, not even close. But the trends are similar (high months are high in both sources, low months low in both, etc.)

I've downloaded data for Jan through Sept of this year for both PG&E and from the Tesla app:
TESLA:

Date time	Home (MWh)	Solar Energy (MWh)	From Powerwall (MWh)	From Grid (MWh)	To Grid (MWh)
2022-01-01T02:00:00-07:00	1.03​	0.44​	0.2​	0.72​	-0.09​
2022-02-01T02:00:00-07:00	0.91​	0.56​	0.3​	0.44​	-0.02​
2022-03-01T02:00:00-07:00	0.92​	0.83​	0.39​	0.29​	-0.15​
2022-04-01T01:00:00-07:00	1.21​	1.08​	0.45​	0.46​	-0.27​
2022-05-01T01:00:00-07:00	1.11​	1.32​	0.44​	0.29​	-0.45​
2022-06-01T01:00:00-07:00	1.36​	1.27​	0.45​	0.52​	-0.37​
2022-07-01T01:00:00-07:00	0.94​	1.24​	0.35​	0.31​	-0.57​
2022-08-01T01:00:00-07:00	1.19​	1.08​	0.46​	0.39​	-0.21​
2022-09-01T01:00:00-07:00	0.89​	0.74​	0.41​	0.35​	-0.17​
	​	​	​	​	​

PG&E:

Month	Total kWh
Jan	962.72​
Feb	681.83​
Mar	456.13​
Apr	461.02​
May	-27.49​
Jun	543.37​
Jul	-43.79​
Aug	725.99​
Sep	618.55​
Oct	0​
Nov	0​
Dec	0​
Total yr	4378.33​

I recognize that the "from grid" data from Tesla is going to be always positive... or at least I think that's true. But when I add the "from grid" and the "to grid" columns in the Tesla data, the result is still very off:

What math is going to get me a version of the Tesla data that is within a ballpark of the PG&E usage data? I understand that CT's are not as accurate as PG&E's smartmeter, but still these data are way off.

Any help understanding this would be greatly appreciated.

Note: I don't care at the moment about the dollar values associated with these data. That gets way too confusing. I'm just hoping that the actual power flows, regardless of the price, match up, and wondering if I need to get anything fixed so I'm not under or over paying for my PG&E service. Thanks!!!

 

[seenhear]

Note: I created the monthly PG&E data from their hourly downloaded data, by summing the data from every day of each month, because my monthly PG&E data is from the 25th-24th or so of each month, which doesn't match with Tesla's monthly data. I confirmed that if I sum the PG&E daily/hourly data from the 25th-24th of consecutive months it matches the PG&E monthly data exactly. So I'm confident in the PG&E data.

 

[jjrandorin]

Note: I created the monthly PG&E data from their hourly downloaded data, by summing the data from every day of each month, because my monthly PG&E data is from the 25th-24th or so of each month, which doesn't match with Tesla's monthly data. I confirmed that if I sum the PG&E daily/hourly data from the 25th-24th of consecutive months it matches the PG&E monthly data exactly. So I'm confident in the PG&E data.

So, I am not the most math minded person here, but this sounds like you are saying "My PGE months are from the 25th of one month to the 24th of the next", yet the tesla month is from the 1st to the end of the month. If that is what you are saying, then there are somewhere between 4-6 days different between the "tesla month" and "PGE month" as far as usage data is concerned.

Perhaps thats not what you are saying and I dont understand, though.

 

[ItsNotAboutTheMoney]

So, I am not the most math minded person here, but this sounds like you are saying "My PGE months are from the 25th of one month to the 24th of the next", yet the tesla month is from the 1st to the end of the month. If that is what you are saying, then there are somewhere between 4-6 days different between the "tesla month" and "PGE month" as far as usage data is concerned.

Perhaps thats not what you are saying and I dont understand, though.

No, they were just noting that they had to use the hourly data for PG&E and sum it up, because the month starts on a different day.

 

[offandonagain]

Is it possible you have house loads that are not monitored by CTs? For example loads that are not backed up or were added later.

You could compare the difference in real time by looking at the Tesla app and the SmartMeter, while turning on individual loads (preferably while you’re not exporting anything).

 

[seenhear]

No, they were just noting that they had to use the hourly data for PG&E and sum it up, because the month starts on a different day.

Correct

 

[seenhear]

Is it possible you have house loads that are not monitored by CTs? For example loads that are not backed up or were added later.

You could compare the difference in real time by looking at the Tesla app and the SmartMeter, while turning on individual loads (preferably while you’re not exporting anything).

I thought this was the case, and posted recently asking about CTs, related to this. But the other day I tried firing up the AC and watched the app and could see the usage jump by a few hundred Watts. So then I checked the oven, and it also caused a jump in the app. The oven, AC, and hot tub are the only things not on the powerwall backup. So it seems as if the oven and AC at least have CTs; I haven't been able to confirm the hot tub yet.

 

[Redhill_qik]

I thought this was the case, and posted recently asking about CTs, related to this. But the other day I tried firing up the AC and watched the app and could see the usage jump by a few hundred Watts. So then I checked the oven, and it also caused a jump in the app. The oven, AC, and hot tub are the only things not on the powerwall backup. So it seems as if the oven and AC at least have CTs; I haven't been able to confirm the hot tub yet.

Firing up the AC and oven should have resulted in several kW increase not a few hundred Watts. You should compare the instant reading of the SmartMeter to the Tesla app grid number.

 

[seenhear]

Firing up the AC and oven should have resulted in several kW increase not a few hundred Watts. You should compare the instant reading of the SmartMeter to the Tesla app grid number.

I double checked the oven today - I don't think it's monitored. I must have had confounding flows when I tested it before. This morning, I was alone at home and turned everything off in the house I could. Baseline power in the app was 300W, I turned oven on to 400F and it got hot, but no change in the 300W usage shown in the app. I didn't compare to the smartmeter at that time.
Testing the AC, when I turned it on, consumption spiked from 300W to 1.6kW, then settled a few seconds later at 1kW. When I turned it off, it dropped back to 300W. I didn't have time to go check the AC panel label to confirm it's rated consumption, but 700-ish W sounds about right to me.

What's strange is both AC and oven (and hot tub) are on the old panel. Surprising that one item would be monitored by Tesla system and not the others. I wonder if the og installer had a CT for the AC, but not for the other two. I'll have to open the panel and see if I can tell. Haven't done that yet.

In other news: Tesla Powerwall tech support finally (a week later) responded to my message, and said they are reviewing my case, and will get back in 20-25 business days. A month. Wow. :-/

 

[charlesj]

My system is certainly different from your and I have Enphase inverters that are claimed to be revenue grade 0.2% and have a Tesla CT
as well on the solar panel breaker. I can compare Enphase data to Tesla data on solar production. Comparing the two reports is withing 0.5% or less.
Not sure how this will help or not but at least my Tesla CT is very close.

 

[dareed1]

Testing the AC, when I turned it on, consumption spiked from 300W to 1.6kW, then settled a few seconds later at 1kW. When I turned it off, it dropped back to 300W. I didn't have time to go check the AC panel label to confirm it's rated consumption, but 700-ish W sounds about right to me.

What's strange is both AC and oven (and hot tub) are on the old panel. Surprising that one item would be monitored by Tesla system and not the others. I wonder if the og installer had a CT for the AC, but not for the other two. I'll have to open the panel and see if I can tell. Haven't done that yet.

700 Watts is quite low for a typical AC system. Is it possible that the blower for the AC is on a backed up circuit while the compressor is not?

 

[seenhear]

700 Watts is quite low for a typical AC system. Is it possible that the blower for the AC is on a backed up circuit while the compressor is not?

Yeah that must be it. I just checked and the PG&E smartmeter jumps from a base of 400W to about 3.4kW when the AC is on. I think our heater/furnace is on PW backup and the blower is part of that, so there you go. AC compressor is not monitored by Tesla system.

 

[seenhear]

Can anyone confirm though, that the Tesla app's "from grid" plus "to grid" data should come pretty close to equal to PG&E's total kWh usage numbers, right? I mean if I have all my usage properly monitored with CTs?
Thanks...

 

[offandonagain]

Can anyone confirm though, that the Tesla app's "from grid" plus "to grid" data should come pretty close to equal to PG&E's total kWh usage numbers, right? I mean if I have all my usage properly monitored with CTs?

Yes, for my system the numbers for the last two weeks are off by only 0.2%.

 

[seenhear]

Just as a follow up to this, I have Tesla Energy scheduled to come to my house tomorrow to figure out what's wrong. Will report back this weekend!
Too bad my solar production is down to almost zilch these days. Not even dead of winter and I'm down to about 2kW peak generation. Was over 6kW in the height of summer.

 

[miimura]

Just as a follow up to this, I have Tesla Energy scheduled to come to my house tomorrow to figure out what's wrong. Will report back this weekend!
Too bad my solar production is down to almost zilch these days. Not even dead of winter and I'm down to about 2kW peak generation. Was over 6kW in the height of summer.

That’s not that bad yet, although you should consider the daily kWh production instead of peak wattage. My system generates only 1/5 of the kWh on a cloudless day in mid-December compared to a cloudless day in mid-June.

 

[seenhear]

That’s not that bad yet, although you should consider the daily kWh production instead of peak wattage. My system generates only 1/5 of the kWh on a cloudless day in mid-December compared to a cloudless day in mid-June.

I'll check. I have just noticed that for the past few weeks, my powerwalls never reach full, and my peak power midday is 1-2kW. Plus I live in the San Jose, CA area, so it's not like I'm in Seattle or Duluth or some other way north city.
EDIT: right now app is showing 2.6kW, so a little higher than I thought. Today is the first cloudless day in a few, so it's better than the last few days.
Total generation is around 15-17 kWh depending on the day.
Late June-Early July total daily generation was in the mid-40's kWh/day

 

[jjrandorin]

I'll check. I have just noticed that for the past few weeks, my powerwalls never reach full, and my peak power midday is 1-2kW. Plus I live in the San Jose, CA area, so it's not like I'm in Seattle or Duluth or some other way north city.
EDIT: right now app is showing 2.6kW, so a little higher than I thought. Today is the first cloudless day in a few, so it's better than the last few days.
Total generation is around 15-17 kWh depending on the day.
Late June-Early July total daily generation was in the mid-40's kWh/day

The numbers that you would be looking at are the last ones you mentioned. Mid 40s during summer, 15-17kWh during winter, for an average cloudless day. That sounds pretty normal. My own generation in summer is about 55kWh, and right now its about 28kWh on a cloudless day, and will get down to about 21-22kW around winter solstice.

 

[seenhear]

Par for the course with Tesla customer service: