I think you are talking about a site's Export Limit . . . ??
That's the state or region DNSP, not any retailer.
It was probably 5kw in NSW not that long ago, and in recent past they moved to flexible export limits, similar (if not the same) as SA has had for many years.
You can have any size inverter you like, and there are many advantages with some systems to have a larger inverter besides what you can feed into the grid.
It's just exports are limited to 10kw max.
If it's like SA and 'flexible' exports, the DNSP can throttle exports to lower limits when there is too much feed in to the grid (to protect it), here in SA flexible exports are anything from 1.5kw to 10kw, and since we have had solar in late 2023, we have never had reduction of the 10kw upper limit, just the annual backstop test (had that yesterday) where the system is tested / shut down (for around an hour, once a year) to ensure they can shut down feed in if here is an emergency situation.
If you have 3 phase you can export the 10kw per phase.
Origins website states "System Limits: Plans like Origin Solar Boost generally require your solar system's total inverter capacity to be 10 kW or less."
If your DNSP has flexible exports you are not limited to any particular limit inverter, or it must be limited in the hardware by the solar company to comply with the DSNP export rules.
