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mismatched readings

Posted: Fri Aug 01, 2025 10:17 am
by Mountjoy House
Hi All,

We have a Fox H1-3.7-E-G2 inverter with a Fox EP11 and a Fox L07PC Car charger & 4.5Kw of Panels

We have noticed a few mismatches on what out octopus mini shows us is happening grid side, with what the inverter says is happening.

for instance this morning, the battery was full, the inverter said we were generating 2.274Kw, using 1.975Kw and exporting 0.299Kw, at the same time our smart meter was recording that we were exporting 1.733Kw, and as none was at home there would just be our base load of a bout 350w'ish

download/file.php?mode=view&id=1846&sid ... c3bfb55a93

I have checked that the CT clamp has the arrow pointing to the grid (and it does).

This causes problems with the car charger sometimes as it is set to use surplus to charge the car, but it never thinks there is enough.
Which has meant i have had to disable the solar linkage, and set a forced charge time on the battery, so that the car will charge from the grid, not the battery.

Any help greatly apreciated.

Stuart.

Re: mismatched readingsowing 1.9

Posted: Fri Aug 01, 2025 3:16 pm
by Dave Foster
Your Octopus mini is a near real time view of energy flow, the Fox screen is based on samples taken every 5 minutes and so it is almost impossible to compare the real time values with it.

Because the Fox system shows data samples every 5 minutes it is also possible to get artefacts where something has juts changed state i.e. if a larger appliance or fridge has just turned off you might see an artificial spike in the values if the sample has just been taken - it’s always better to view the graphs which show power over time and the daily statistics as they will give a better impression of how the system is performing.

I can’t comment on the Fox car charger other than to say that any EV car charger that can charge from solar has to see a a minimum of 1.4kW sustained (usually for 30 seconds) before it will charge.

When you were showing 1.975kw of house load was the car plugged in / charging ?

I should say as a rule whatever the Octopus mini says will be the correct ‘actual’ reading

Re: mismatched readings

Posted: Sat Aug 02, 2025 5:45 pm
by Mountjoy House
Hi Dave,

Thanks for the reply.

No the car wasn't plugged in.

What we have noticed watching the app and our meter is that as soon as the battery is full, the app shows our house load shoot up at the same time the meter shows we are exporting, as this is showing as load, not surplus, the car charge will not turn on.

To counteract this, I have set the battery to charge between 00:30-5:30 (our cheap rate) and turned the solar linkage off on the charger and set that to force charge the car at the same time.

I have included 2 graphs of the same day, one from our inverter and one from our meter.
Capture 1.JPG
Capture 2.JPG

Re: mismatched readings

Posted: Sun Aug 03, 2025 9:40 am
by Dave Foster
Hmmm yes, something wrong if the load goes up when you should be exporting - with a normal system without a Fox EV charger I would say your CT clamp was in the wrong place, but the Fox EV charger adds another complexity to it as I think it also measures the load and the cloud performs some maths so that your load, export and consumption figures show correctly.

The EV charger can be fitted with a separate meter as well and so you really need to know how it has been installed to asses the next steps - i'm not that familiar with the L series but I would agree that the system is not working as it should and so i;d recommend that you get your installer involved, they may need to speak with Fox but they will have a direct channel to their support team.