This will kill new household solar instillation.

The payback time was already well in excess of 10 years, but now that power is free during the day, you can't count those hours as helping pay down your investment. Payback time will be 30 + years at least. You are much better just enjoying your neighbors solar rather than paying for your own.

(Feed-in is about 3c now I think. Was 12c when many people bought their panels.)

Note: My state 100% renewable energy so reduction of carbon footprint has not bearing on my solar decisions.

This also feels like a fairly heavy handed way to encourage investments in batteries. But in the famous words of George W, "can't fool me again". As soon as there are too many batteries and the grid companies are not making enough money, they will introduce fees to have the batteries, or increase connection fees.