Hey @Lester & @Steve4567,
You're both right, standard solar feed‑in rates have fallen over time. The reason is supply and demand. So much rooftop solar now feeds the grid that midday exports are worth very little across most of the NEM, not just South Australia. The midday "sun tax" is set by SA Power Networks under the regulator, so it isn't something retailers add on.
But solar isn't a "dead duck", its value has simply moved. What matters now is when you use or export your energy. That's ...