Sunamp heat batteries

Recently I came across Sunamp heat batteries which are direct replacement to Hot water tank and very efficient way to store excess PV. They have efficiency of over 96% and no drop even after 45000 . Anyone on the forum using them?

Really like the idea, but have you seen the price? Over 3,000 for the 12kWh version which is roughly equivalent to a 250 to 275 litre regular hot water tank that can be had for under 500.