Apparent discrepancy between metering systems

[sathornlover]

On 7/20/2024 at 4:10 PM, 4myr said:

@sathornlover

 Have you checked the PEA smart app? There you can see your monthly bills. I don't know if they will report credit bills as well.

Thank you for suggesting the PEA Smart App. I had installed it before but didn’t realize its potential benefits. Upon reinstalling, I found that the app allows access to all past bills, including the one for July, issued on August 1. Future bills can also be sent via email if desired. There is really nothing negative to report about this app and all the relevant data is presented relatively well, but also less comprehensibly if you look at it in more detail. Another positive thing I noticed is that the service fee is 24.62 baht, just like the old meter. This solves at least one of our problems regarding digital access to invoices, so thank you once again for this very useful information, which we unfortunately didn't receive from the PEA during our last visit for whatever reason ...

 

 

Even at first glance, I noticed that we now have a completely new problem. Strangely enough, there is a considerable discrepancy between the units used 302 shown on the bill for the month of July and what our smart logger from Huawei records (208).

 

 

 

 

 

Then on closer inspection of the July bill, I also noticed the feed was off by 100 units, this time in my favor. Around 790 versus 699 units.

I also found the first bill suspicious, which was presented to us during our last visit but we weren’t allowed to photograph. My rough calculations suggested a payout of around 1000 Baht, but the bill showed only about 650 Baht. This bill combined the last days of May, when the new digital meter was installed, with June, and I didn’t want to dispute it.

 

For the July bill, I expected a payout between 500-700 Baht, but it turned out to be only 357 Baht. I was confused and reached out to my PV installer via Line last night:

 

“Dear Anan,

 

I apologize for reaching out to you again, but I’ve noticed a significant discrepancy in the last two monthly statements from PEA. The discrepancy is between the units of electricity consumption recorded on the PEA bill and the units logged by the Huawei dongle logger. The difference is so substantial that I can’t explain it, and I doubt I’ll get satisfactory answers from PEA.

 

Basically, in my view there are three possibilities:

 

1. PEA is not correctly recording the units of electricity we consume from their grid.

2. The Huawei system is not accurately recording the consumed units from the PEA grid or is misconfigured (for example, the system might prioritize feeding electricity back to the grid over meeting your household’s consumption needs first).

3. I’m making a calculation error, or PEA is using an algorithm to calculate the units that I’m not aware of.”

 

 

I received an immediate response and assurance that he would look into it today, Sunday. He not only reviewed the July bill but also the combined May/June bill, created a data sheet, and advised me to present it to the PEA during our next visit, as he found both bills suspicious as well.

 

For those unfamiliar with digital meter bills, unlike the old analog meters, the digital ones have three reading marks: P (peak), OP (off-peak), and H (holidays, i.e., weekends and public holidays). These three values add up to 302 units. The upper part of the bill strangely shows values from the old analog meter, which don’t factor into the calculation and make no sense. I hope to get a reasonable explanation for this oddity soon …

 

Since I have no need for a TOU tariff and we charge our EVs for almost zero baht during the best daytime hours with our ABB charger, all units we draw from the PEA grid are charged at the standard electricity rate.

 

 

 

 

[lom]

You have a discrepancy of 94 unit in import but you do also have the same 94 unit discrepancy in your export.

At a first glance that seems to indicate that the 94 units you import flows out directly and the inverter doesn't see any of that.

Maybe it is just a coincidence that the error is the same in both directions..

 

[sathornlover]

14 hours ago, lom said:

You have a discrepancy of 94 unit in import but you do also have the same 94 unit discrepancy in your export.

At a first glance that seems to indicate that the 94 units you import flows out directly and the inverter doesn't see any of that.

Maybe it is just a coincidence that the error is the same in both directions..

 

I don't think it's a coincidence, I really didn't notice it. I had 690 export units in mind, thank you for taking the trouble to look into it more closely 😉 and for your further conclusions. I would like to give it more than a thumbs up! I'll just wait for the bill for this month and instead discuss the problem further with the installation company...

[sathornlover]

6 hours ago, sathornlover said:

I don't think it's a coincidence, 

"Coincidentally," my ABB charger used 186.7 kWh in July, which is almost exactly the sum of the export and import discrepancy in the July electricity bill. Another „coincidence“, or are we already on the trail of the culprit?

 

[UWEB]

2 hours ago, sathornlover said:

"Coincidentally," my ABB charger used 186.7 kWh in July, which is almost exactly the sum of the export and import discrepancy in the July electricity bill. Another „coincidence“, or are we already on the trail of the culprit?

 

Where do you get this Report from?

[lom]

3 hours ago, sathornlover said:

"Coincidentally," my ABB charger used 186.7 kWh in July, which is almost exactly the sum of the export and import discrepancy in the July electricity bill. Another „coincidence“, or are we already on the trail of the culprit?

I don't think it is related and I have a problem understanding the export discrepancy, that's why I suggested that the same units might be a coincidence.

The inverters metered import can be wrong if there is a consumer connected between the PEA smart meter and the inverters external current transformers which measures power flow and its direction. The inverter will not see the power going to that consumer because it is on the wrong side, before the current transformers

I can't understand though how you can export more than what the inverter think it has exported.

Is your system a single phase or three phase system? Where/how is your ABB EV charger connected?

Edited August 5 by lom

[sathornlover]

perhaps a moderator reading this could separate this discussion thread because it has nothing to do with the actual topic and it was not my intention to steer it in that direction.
Sorry about that!
 

The report is a statistic of my three-phase ABB charger, which also supports load balancing, for our electric car.

 

Two years ago I ordered a three-phase electricity meter for this. Then a year later a three-phase solar system was installed. The original house installation, which was still running on the old one-phase electricity meter, was also integrated, so that everything now runs on just one electricity meter and finally two months ago the switch from analog to digital electricity meter.

[Crossy]

43 minutes ago, sathornlover said:

perhaps a moderator reading this could separate this discussion thread because it has nothing to do with the actual topic and it was not my intention to steer it in that direction.
Sorry about that!
 

The report is a statistic of my three-phase ABB charger, which also supports load balancing, for our electric car.

 

Two years ago I ordered a three-phase electricity meter for this. Then a year later a three-phase solar system was installed. The original house installation, which was still running on the old one-phase electricity meter, was also integrated, so that everything now runs on just one electricity meter and finally two months ago the switch from analog to digital electricity meter.

 

Done.

 

If you want to adjust the topic title please let me know.

[lom]

1 hour ago, sathornlover said:

Two years ago I ordered a three-phase electricity meter for this. Then a year later a three-phase solar system was installed. The original house installation, which was still running on the old one-phase electricity meter, was also integrated, so that everything now runs on just one electricity meter and finally two months ago the switch from analog to digital electricity meter.

I would check your current transformers, it could be that one is faulty or disconnected which would make the inverter only measure power on 2 phases.  That is the only thing that  came to mind which will cause a discrepancy in both directions.

 

On 8/4/2024 at 8:28 PM, sathornlover said:

The upper part of the bill strangely shows values from the old analog meter, which don’t factor into the calculation and make no sense.

I think those are reactive power which they just measure but don't charge you for. I do also have a digital meter but not an export one and therefore get a bill looking a bit different from yours but it shows a monthly slightly increasing value for reactive power.

All digital meters display this, analogue meters can't measure it.

Edited August 6 by lom

[lom]

2 hours ago, lom said:

That is the only thing that  came to mind which will cause a discrepancy in both directions.

 

but I still don't like that the units in error are the same in both directions. There is something fishy going on..

[sathornlover]

21 hours ago, lom said:

I would check your current transformers, it could be that one is faulty or disconnected which would make the inverter only measure power on 2 phases.  That is the only thing that  came to mind which will cause a discrepancy in both directions.

I have to add to my three-phase ABB charger that I am not at all sure how it was actually wired, because two years ago the first charger installed was a no-name single-phase charger and this was then integrated into the solar system installation as already described. The single-phase charger was then simply replaced six months ago by the three-phase ABB charger. I have now asked the installation company to send a technician to me next month after the August electricity bill, as this is when the annual inspection should have been carried out anyway.

 

Quote

 

I think those are reactive power which they just measure but don't charge you for. I do also have a digital meter but not an export one and therefore get a bill looking a bit different from yours but it shows a monthly slightly increasing value for reactive power.

All digital meters display this, analogue meters can't measure it.

 

 

For this helpful and comprehensible answer alone, which even my installation company still owes me, I pity again that I can only give it a single thumbs up.

 

Quote

but I still don't like that the units in error are the same in both directions. There is something fishy going on..

 

Full agreement but at least a clear symptom to work on now 🙂

 

 

[lom]

Is your ABB charger able to feed back from the cars battery to the grid (V2G, vehicle to grid) ?

If it is then I think I know what is wrong.

[sathornlover]

The ABB charger TAC-W22-G5-R-C-0 was a "free" gift from BYD and to my astonishment is one of the better wallboxes, but the v2g/v2h capability is missing from this device, neither in the descriptions nor on the net can I find any reference to it.

 

[lom]

Ok, so then it isn't your ABB charger that is responsible for the additional export so it must be your inverter exporting more than itself is aware of.

I'd say that is very unusual, close to  impossible..  I'm looking forward to hear the result in end of August.

[UWEB]

9 hours ago, lom said:

Ok, so then it isn't your ABB charger that is responsible for the additional export so it must be your inverter exporting more than itself is aware of.

I'd say that is very unusual, close to  impossible..  I'm looking forward to hear the result in end of August.

I have had a Huawei Inverter as well. Even set to no export I had appr. 4 kwh ghost Export every day. You could not see it on the old disk Meter, but I have got a digital ones installed by PEA. After this my monthly Bill increased by 25%/

[lom]

47 minutes ago, UWEB said:

I have had a Huawei Inverter as well. Even set to no export I had appr. 4 kwh ghost Export every day. You could not see it on the old disk Meter, but I have got a digital ones installed by PEA. After this my monthly Bill increased by 25%/

Something must be wrong in your description, you don't get charged for true or ghost export.

Export is separately metered by PEA and you either get paid for it if you have an export contract with them or you will get nothing without a contract. It never affects your imported units.

 

Edit: Where do you see those 4 units of daily export?

Edited August 8 by lom

[sathornlover]

On 8/7/2024 at 6:22 PM, lom said:

Ok, so then it isn't your ABB charger that is responsible for the additional export so it must be your inverter exporting more than itself is aware of.

I'd say that is very unusual, close to  impossible..  I'm looking forward to hear the result in end of August.

 

As was to be expected, there is also an equally large discrepancy in August,
 this time of ~139 units between the two meter systems: import 424 units vs. 284.6 units and export 1025 units vs 886 units.
The charger for the EVs shows ~261 units for this period, which this time does not quite match the export/import discrepancy values
when these are added together. 278/261
In the month of July: 188/187

 

 I won't be in Thailand for the next whole month, so only my wife will be charging her car, which she only uses for the commute to work - that's an average of ~100kWh, so the discrepancy between the export/import values should be smaller, if the assumption that this problem is related to the charger is correct.

 

An electrician from the installation company is coming by on Saturday ...