In the long run this sort of model probably makes sense, but it's far too soon as it discourages solar and battery uptake and increases the relative burden on the poor.

Once we have more solar and batteries than we can possibly use, an unlimited model with a monthly fee would be best (like how we pay for internet access), but that's probably 10+ years away. Ideally, those on low incomes would have subsidised bills too so they are not eating proportionally more of the costs.