Are Solar Panel's worth it?

We have been connected to the grid for a whole month now which allows me to make some projections. Based on the projection calculated by experts for a 9kw system, I have used these figures to calculate our 6.5kw system. Our yield might be slightly lower seeing as we have a 5kw inverter, so it can't put in more than 5kw's at any one time. I was a bit skeptical of these figures at first but we averaged 30.92 kWh/day of solar production for October, so they could be right. With a feed in tariff of 11.3c, we should be in credit by $1,160 in a year. At present we are using an average of 4.9kWh of energy straight from the panels per day. We pay 17.853 (incl GST) per kWh from the grid, so that equates to a saving of about $320 a year. The cost of the solar system was $10,030 before any rebates were applied (Sept-18). The first rebate was $3,535 and the new Victorian Government incentive is $2,225, though we haven't received the second one yet. This will bring the tota