thanks Bruce , I'll try to digest it all.
Quick look , it seems strange that there's not clear guidance from Ofgem ; with higher effiency panels coming on the market , getting as close to 4kWp and more importantly the 16A limit ffor easy installation on to the grid , is surely in the interest of the FITS funded national PV project
Getting as big and cost efficient system on each household as poss. to maximise returns for all. ( including us the energy bill payers funding this FITs scheme)
use a 4000TL, change the maximum output setting to 3680W, change the installer password to prevent the customer changing the settings back, make a clear note of this on the DNO notification form stating that the inverter output is limited to 3680W / 16amps AC.
Job done.
Biggest system we've installed this way is 4.5kWp DC, with the rating for both G83 and MCS/FIT purposes being the 3680W or 16amps.