Re: "...$15,000 easily recoverable over ten years..."
Australian electricity seems to be around 14 AU cents/kWh so 15,000 AUD would buy 107 MWh of mains electricity. Your battery would have to provide a bit more than 29kWh per day every day for 10 years. Presumably the 15,000 AUD was only for 2 x 10kWh batteries since that is all the Hackett bloke said he would be trialling.
Of course that would only be if the electricity you are charging with is free which it isn't when it comes from a large and expensive set of solar panels which will also be half knackered in 10 years.
I would also be very impressed if their batteries manage daily deep cycling every day for 10 years, presumably they loose capacity and would have to be oversized to maintain an average over their life.
"you need to load shift 45,000 kwh to pay for them."
If it were economical to time shift electricity with batteries why don't the electricity generators do it with much more economy of scale?