I have recently installed a 6kW system, and after investigation settled on 2 x 3kW Fronius inverters. Happy with the result and in particular the Fronius "solarweb" interface.
Fronius have published their API and I have managed to import data into Indigo for display on a control page - but a plug in is beyond my limited time availability - not to mention my even more limited coding skills
Having had this data visible has proved useful, as it identified an over-voltage issue on the grid, that was sending the inverters into power limiting mode and in extreme cases shutdown of export to the grid. This is regularly (almost daily) limiting the energy exported to the grid and the financial benefits of the associated feed-in tariff. The supply authority has acknowledged the issue and is in the process of rectifying it.
In making the decision on "matters solar", I found this web site useful:http://www.solarquotes.com.au
Although specific to the Australian market, it does provide some useful equipment comparisons and user reviews that may have more global application/value.
Good luck with your investigations!