You can download the SMA software from SMA Australia and then monitor your system on any bluetooth equiped device, It's free. we now advise people of this rather than flogging them a sunnybeam.
Yingli are good, I fitted them on my demo system and my mates house and they are performing very well. The demo system is a 1.8kW. I don't entirely agree with SRE. even a 1.8-2.0kw system will give you useful savings and a FiTs payment, it's still well worthwhile. Maximmise the output of what you have available (maybe by using 270 panels as he suggests), microinverters, or top of the range panels like panasonic IF, as I suggested before, it means you can get more panels on the roof. IF it doesn't it's probably not worth the cost.
A good quality inverter like SMA will be fine in your loft if you have nowhere more suitable.