As you say, with Amber and the solar duck curve you'll be faced...

As you say, with Amber and the solar duck curve you'll be faced with the prospect of low or negative prices during the day so yes, battery(s) makes sense, but not so much solar panels when you can charge a battery for low or negative cost during the day. Even with other retailers the FIT you can get during the day (in QLD at least) is approaching zero in any case.

Where solar might make sense is if you have an EV and can charge it during the day from your own solar, but even then with Amber you may be able to get paid by charging it during sunny days when prices are negative so not necessarily any advantage having solar. Two or three years ago this would not have been the case...

I have a large solar system and batteries, which made sense a few years ago before FITs plunged, but not so much any more (the batteries do make sense for handling blackouts, not that uncommon where I live). At least I do get sufficient FIT to make the power bill negative over the long term, and the excess solar keeps the EV charged for free. Not Redflow batteries unfortunately - Energex inverter capacity rules (5 kW max per phase did not allow for AC-coupled batteries as well as a solar system in my situation (single phase grid supply with no possibility to upgrade to 3-phase).

Good luck with your system!