So the Powershop EV one is 83.6c/day supply charge, 9.9c/kWh "super off-peak" (12am - 4am). Meaning if you charge your car at least an average of 5.2 kWh/day in that 12am-4am window, you'll come out ahead (ignoring the effects of your peak usage, solar FIT etc.). Not sure how much you drive, but I tend to use about 12kWh/day charging the SR+.