App reading not matching up with meter

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cobiofodile
Posts: 1
Joined: Sun Feb 05, 2023 12:35 am

Hi,
Is anyone else noticing the same issue of the foxess mobile app readings for total power generated is not matching with the meter display readings on the solar power installed meter? How can this be rectified.

Also, the export reading figure displayed on my main meter electricity supplier meter does not match / tally with the export figure shown on the installed import/export meter of my solar install.
How can these be made to sync and match up?
Dave Foster
Posts: 862
Joined: Thu Oct 13, 2022 7:21 pm

The FoxESS inverter records it's inputs/outputs using a CT clamp (a clip on transducer), these are typically a few % points inaccurate depending on loads. Trying to compare the output of the inverter to it's inputs isn't a zero sum as there are losses in the ac/dc/ac conversions, in charging/discharging the batteries and in running the inverter itself (~70w)

To get better accuracy in the grid use and export you would need to replace the CT clamp with a meter like an Eastron SDM230 or CHINT DDSU666 they are far more expensive than CT clamps but the accuracy is similar to your smart meter.
Robbo622
Posts: 6
Joined: Sun Mar 12, 2023 2:56 pm

Hi,

I have a 4.8 kW solar system with hybrid inverter and 4.5 kw battery (mira)
The system was installed in June 2022 and the batteries in January this year. All seems to be working fine, but I’m confused about the data from the FoxESS app.

For December 2022 the app says my Grid Consumption was 810.0 kWh. Octopus Energy says my consumption was 1648 kWh. In January 2023 the app says 713.9 kWh against Octopus’ 1450 kWh.

Has something been wired up wrongly?
Dave Foster
Posts: 862
Joined: Thu Oct 13, 2022 7:21 pm

Robbo622 wrote: Sun Mar 12, 2023 3:01 pm Hi,

I have a 4.8 kW solar system with hybrid inverter and 4.5 kw battery (mira)
The system was installed in June 2022 and the batteries in January this year. All seems to be working fine, but I’m confused about the data from the FoxESS app.

For December 2022 the app says my Grid Consumption was 810.0 kWh. Octopus Energy says my consumption was 1648 kWh. In January 2023 the app says 713.9 kWh against Octopus’ 1450 kWh.

Has something been wired up wrongly?
It could be, but that's a big difference - do you by chance have an EV charger ?, if you do then it has been wired correctly to stop the solar batteries discharging when the car charges.
Robbo622
Posts: 6
Joined: Sun Mar 12, 2023 2:56 pm

Thanks Dave,

Yes, I've got an EV charger which was installed before the Solar system. The app shows the EV charge pretty accurately (against the EV charger app), which is done during the Octopus Go reduced rate period. I can't see how this would cause such a discrepancy in grid usage?
Dave Foster
Posts: 862
Joined: Thu Oct 13, 2022 7:21 pm

Robbo622 wrote: Sun Mar 12, 2023 7:22 pm Thanks Dave,

Yes, I've got an EV charger which was installed before the Solar system. The app shows the EV charge pretty accurately (against the EV charger app), which is done during the Octopus Go reduced rate period. I can't see how this would cause such a discrepancy in grid usage?
The CT clamp for the solar charger has been installed after the EV charger so it won't see any demand from the EV charger and be unaware of it - you can move the inverter CT clamp to be in front of the EV charger but then the EV charger would look like house load to the inverter and it would try to supply it from your batteries.

Your supplier grid consumption should be roughly equal to the inverter reported grid consumption + EV charge consumption ( I say roughly as CT clamps can be a few % inaccurate particularly at low loads).
=
Robbo622
Posts: 6
Joined: Sun Mar 12, 2023 2:56 pm

Dave,

Thanks again for your help.
I've checked the data comparing Inverter grid consumption with Octopus readings. when there has been no EV charging, the inverter figures are roughly half of the Octopus figures. When EV charge has taken place, the difference is between 60% & 160% of the Octopus figures. A small, top up charge gives the lower figure, a big charge more than 100%.

I then looked for CT clamps and found only one, attached to the main positive inlet to the consumer board and connected to the hybrid inverter.

I have a SyncEV compact charger installed which has it's own mcb in the consumer unit. I've traced the cable to the outlet and can't find another CT clamp. Before the charger was installed, the house supply had to be uprated to 100 amps with a new supply cable to the meter box. I think this negates the need for a CT clamp to monitor load as the 100 amp system should be more than enough to cope?

I'm puzzled?
Dave Foster
Posts: 862
Joined: Thu Oct 13, 2022 7:21 pm

That sounds very strange, it sounds like the CT clamp is in the wrong place and there is something else upstream of it taking power.

You would normally expect it to be connected to the live feed coming out of your meter, but when there is an EV charger installed they sometimes fit a henley block which splits the feed so that the house load/inverter is on one feed and the EV charger is on the other, from what you have said the EV comes off the main consumer unit so the inverter CT clamp should be measuring that load.

The CT clamps job is to measure the entire house load and to be able to detect the amount of power being exported back to the grid - It depends on the EV charger brnad as to whether they fit a CT clamp or not, it would be essential if the maximum demand of the house exceeded your main fuse, but at 100A you are quite safe.

CT Clamps can be disturbed by close proximity of other cables and interference, so it's possible something inductive is causing it to misread but the amount it's mis-reading by is extraordinary - it could also be faulty (or the wrong one fitted - it should be a white clamp with black cable) but that's very unusual.

So the big question, is there something in front of the main consumer unit, another house feed (garage, shed), split consumer unit ?

In an ideal world I would suggest the CT clamp is moved to the live tail coming out of your meter - that might not be so easy depending on where things are laid out - can you contact your installer and ask him to check the system/move the CT clamp.
Robbo622
Posts: 6
Joined: Sun Mar 12, 2023 2:56 pm

Thanks Dave,

I've moved the clamp as you suggested, it was very close to a bundle of cables coming out the top of the consumer unit. I'll report back on how it affects the data.....
Robbo622
Posts: 6
Joined: Sun Mar 12, 2023 2:56 pm

As promised, an update.

There is still a 50% difference between the Foxess app and Octopus energy data for grid consumption, Octopus saying I'm using twice the power the apps says. I contacted my installer to ask if the CT clamp might be defective, but they wouldn't have it!

So I sent an email with my data, screen shots of the app data and photos of the CT clamp and EV charger setup. So far, after four weeks, no reply.......
petr.domo
Posts: 1
Joined: Sun Nov 05, 2023 8:31 pm

Hello, is there a way to adjust the recovery time in the Foxcloud application or foxcloud webside from 5 minutes to maybe 2 minutes? Thanks
Dave Foster
Posts: 862
Joined: Thu Oct 13, 2022 7:21 pm

petr.domo wrote: Sun Nov 05, 2023 8:39 pm Hello, is there a way to adjust the recovery time in the Foxcloud application or foxcloud webside from 5 minutes to maybe 2 minutes? Thanks
No unfortunately not, it used to be configurable but as the numbers of users have grown they have fixed it at 5 minutes.

It is possible to connect the inverter via an RS485 link to a home assistant, that gives you near real time updates.- there is more information about that here https://github.com/nathanmarlor/foxess_modbus
Davyd
Posts: 1
Joined: Thu Apr 18, 2024 6:31 pm

I have an issue where my export as per my main meter is approximately half of what I think I am exporting. I have a clamp and also the PV manufacturer's app and they closely agree i.e. I think I am generating 2kWh but I am only being credited with 1kWh.
Is this a similar problem to what is on this thread ?.
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