I've seen no mention of arc fault
Me neither but I’m not sure how much of a concern that is with low-voltage single-panel ‘strings’.
Pretty certain that any ‘grid-tied’ inverter is rapid-shutdown by definition (grid signal goes away and output get cut off).
Any grid-tied inverter supports AC-coupling (by definition). Do you mean ‘frequency shift’ (throttling-back output when off-grid by increasing ‘grid’ frequency)?
but I've not looked. None of which I need for my current application but certainly not something to ignore. I will say that the supplier is very responsive and has been able to answer all of my questions.
The key missing spec that has caused me to hold off is efficiency - perhaps you can ask you supplier for power efficiency (how many Watts of DC input power needed t generate 1000W or 500W of AC output power?).
Also, I assume you know these inverters can be purchased through Amazon:
https://www.amazon.com/gp/aw/d/B07N...d2lkZ2V0TmFtZT1zcF9waG9uZV9kZXRhaWwp13NParams
With Amazon, if you get the vendor to indicate a Power Efficiency % either in an email or in an ‘Answer’ to a question you ask on Amazon, if the inverter fails to deliver the stated efficiency you can return it for a full refund.
In my experience, the premium of purchasing a first sample of any unknoen Chinese product through Amazon is generally money very well-spent…
[EDIT: no need to ask a question as that vendor indicates a power efficiency of 91.2%:
That’s actually better than I expected.
If you can get 1000W of AC output power from 1096.5W of DC input power, that’s only 96.5W of heat being generated.
Not as good as the 95.5% efficiency of the NEP Microinverters, but closer to them then the 80% Power Efficiency of the GTIL inverters…]