Generation Meter

We had our panels fitted last July and the generation meter appeared to be working fine; battery storage wasn't added until October (due to supply issues) and I have just noticed the red light flashing on a night and on checking the reading it is actually increasing overnight; I suspect that the generation meter now appears to be recording not just what is being generated by the panels during the day but also everything that is coming out of the battery on a night, which includes any grid power used to charge the battery. I can't believe that this is correct but after querying with my installer I received the following reply:
"As you have a Hybrid inverter there is No way of the inverter distinguishing between the solar generation & the battery/house demand as the generation meter is installed to the single line mains supply to the inverter so will register both. The generation meter is not installed as a client monitoring piece of equipment but a mandatory requirement to allow the DNO to see the generation as/when/if needed."
I cannot understand how the DNO would be able see our generation if the reading also includes everything going back to the house from the battery (double count of PV generation plus grid power used to charge the battery!).
I would appreciate the expert opinions from this forum.

MCusters
see this post and the system layout
Have you got a sketch - however crude of where everything is
https://community.givenergy.cloud/d/1859-plant-system-power-graph

MCusters that is correct. The "generation meter" is a requirement of the MCS and DNO processes.
It is a BiDirectional meter so it cannot distinguish between what is generated by your solar panels and what is supplied from the battery.
You should have an additional LED/LCD meter installed either an EM115 or EM418.
https://midsummerwholesale.co.uk/pdfs/giv-brochure-2019.pdf
These meters will show you what your actual PV generation values are.

Whoever your SEG is will probably require pics of the generation values from your DNO installed Smart Meter (the one in your meter box).

Which type/brand/model meter you have will determine how you obtain this.

Ours is an Emlite EML22 and the secret code was Press Button A Twice, then press and hold Button A for 3-4 seconds, then press Button A 9 more times......

MCusters Why does the DNO require to know your generation? Panels fitted last July will not qualify for FIT payments which is only for generation but any export will qualify for SEG payments. SEG payments are for export regardless of the source. If you export from battery you should get SEG payments for it. Your smart meter should be the arbiter for export.

MCusters As @dragon2905 says, it should be a meter with two registers; one that registers energy to the inverter from grid to charge the battery and the other that registers energy from the inverter which will be a mix of PV and battery. Some meters have a net register which subtracts one from the other which will be the amount of PV generated (less inverter losses charging and then discharging the battery). In theory, the meter should be accurate because all of the energy produced by solar panels will pass through the meter, either at the time it is generated, or later when discharging the battery. In practice, they don't seem to balance up when other means of measuring energy is added to the picture. Probably best to ignore this meter as it plays no part in controlling the inverter and no part in your relationship with your energy or SEG supplier. The only reason why it has been installed is because you want an installation with an MCS certificate which you need in order to get an SEG tariff and when you sell the property, it is an assurance to the buyer that the system complies with regulations.

dragon2905 These meters will show you what your actual PV generation values are.

In my experience, these meters can only provide gross PV when installed as a second meter on the Givenergy AC-coupled inverters. For a hybrid system (which this is), the role of the EM115 is to provide the inverter with a control signal to enable it to minimise grid import/export.

And @cluelesscris is right that the DNO doesn't care what you have generated as long as your instantaneous export power doesn't exceed the limit specified in the DNO agreement letter. That isn't measured anywhere unless your energy supplier meter (Smart meter) has a maximum power register for export, although the 30 minute DCC data could show an export in excess of the limit, if it was sustained for the whole period. Either way, the DNO isn't looking at your DCC data.