I have just installed a 5kw system in QLD. I have 24 panels which add up to 6kw and a 5kw inverter. Panels are Mono crystaline A grade and inverter SMA 5000TL. Price $11990. My roof faces directly north and all panels are on the same section. My installer came twice, once to rough measure and give us the info and the second time to sign us up. There were a couple of phone calls from us too. The last time was after the inverter was approved and when asked he said 4 weeks, when he realised the inverter was approved he said how about tomorrow, so now its on. About 4 blokes rocked up at about 11am and all done by 5pm.
Whilst getting quotes we encountered all types of sales people from the really pushy to the not so. But most quotes were not too far apart. I used this site for info which I found very good
http://www.solarquotes.com.au/index_a.html. I also found or was given a site which allows comparisons between panels, sorry cant remember it. Only time will tell how long it takes to pay for itself but installer reckons 3.5 years. Elec companies here in QLD are paying between 44 and 52c pkwh so check that also.
Happy solaring.