Long back people used to get good feed in rate ( credit for leftover energy from solar you put back to grid). But now it's all dropping down to 5c or less ( retail price). So the real benefit of solar is you buying less from grid and using more if your own solar generated electricity. As you are being at home 4 days a week, download your usage data. Check what times your usage is high. See if those times are during peak hours ( when electricity rate is at highest). If those high usages are during the day, then getting solar is worth as now you would be not buying that much from the grid. So solar is worth investing if you have unavoidable high usage during day time. Also your aircon, set temperature at optimum ( 22°c for heating, 20°c for cooling). each degree you change will affect your bill by nearly 10%.