I have had solar for 1 1/2 years and no battery and so far no bills. 6.6kw system (20 panels) my bills were around 450-550 per quarter BUT I live in Townsville and the sun today is directly above us and the solar output is good I'm allowed to export 5kw per hour and can do 4998kw per hour for most of the day My solar supplies the house first and what is left over is exported so working well Ian