I have. 9 panels producing 2.25 kW max.
I did it as an investment, not as an exercise in green living as I think if you're doing it to be green then solar thermal makes much more sense. Due to the Feed-in-tarriff scheme however, the solar PV business case is much greater.
Installation costs have come down with the feed-in-tarriff dropping. e.g. my father's system was about 9.5k to install, but has around 30p FIT whereas mine cost 4.5k with 15p FIT. So, payback timescales remain at 7 to 8 years, depending on how greedy the power companies are (FIT rates are guarenteed for 20 years)
I am blessed with an electricity meter that runs backwards (don't worry - I've informed the supply company so they know about it) but what that has shown me is that 2.25kW is plenty of energy. I was still exporting to the grid with the dishwasher, washing machine, freezer, fridge and TV/Sky box on and running!