Net reading reducing

I'm sure this will have come up before but despite searching can't find anything. I have house battery and solar going through a bi directional meter and in winter have noticed the net reading is slowly reducing obviously affecting my FIT payments. I figure this is because I'm importing off peak to my battery and losing 10 % due to inefficiency in the conversion AC - DC - AC this discrepancy meaning when the meter reads the export it's 10% less and and this comes off the summers solar generation effectively. As there is not much sunshine at the moment and I'm charging for 5 hrs. off peak the solar isn't enough to match the 10 % loss and so the net reading reduces. Effectively it isn't recording my PV generation till it catches up in the better weather and reduce charging times losing me FIT payments.
Two questions to anyone who can help - Am I correct in my assumption that this is the reason it goes backwards and are there any meters that are fit compliant that can read off the DC from the PV array. If so could install one and wouldn't need anything on the battery side.

I'm struggling to picture your system. The way you describe the meter, it sounds like it has a single counter which adds +1 for each unit imported, and -1 for each unit exported, so that it only has a net figure, and it can't distinguish import from export. But I'm sure that can't be right.
I'm not sure why a battery should have any effect on your FIT payments: I was under the impression that, while you could add an AC-coupled battery afterwards, it would be metered separately from your solar, since you couldn't expect to receive FIT payments for anything you exported from your battery. But maybe you got the battery installed at the same time as the solar system - I think FIT arrangements did continue up until quite recently ?

It's true that battery will suffer approx 10% losses from input to output, but I assume that while you charge your battery from grid through the meter, you would consume it domestically, and so the power wouldn't pass back out through the meter again.

It's a bi directional meter which works like this:
it scrolls through 3 readings

The IMP register will record any power that is taken from the grid to charge your battery.

The EXP register will record any power coming from your battery or solar system into your home.

The NET register will record EXP minus IMP to give you what your solar system is producing (which is what you will give for FIT payments).

because of the 10% loss the imp and exp aren't equal if they did it would record your solar accurately as the excess. For instance on a 10 k charge it only registers 9 k going out so when you take exp minus imp your net goes down a unit. So if you get 5 kw of solar over say 10 days whilst doing a 10 k battery charge every night your net reading will have gone 10 kw because of the above inefficiency. This means your 5 kw of solar isn't recorded as it's lost in recovering the battery loss so no fit payment for it's generation.

GrahamVeevers ah, okay, I think I understand. It's as if you had a hybrid inverter, so in order to isolate just the solar for fit generation payment, you need to subtract battery import.
Presumably your FIT provider requires a properly calibrated meter, and won't trust the inverters own readings.
Not quite sure what you can do, really. Perhaps submit a reading at the start of December, to ensure that you get paid for generation up to that point. Accept zero generation for Dec/Jan, and then start February with a clean slate. Not ideal, but at least your net import through the worst months doesn't cancel out generation from the rest of the year.
Might be extreme, but guess regularly switching fit provider might be a way to enshrine that. (Sorry, don't a great deal about fit system.)