I'm probably not much use to you as am in Australia but we have just had solar panels fitted. We had solar for the hotwater only done last year, and then had solar pv fitted 10 days ago, just in time to catch the govt rebates here.
Our system is a 2.7kW (12 panel) system, which will not supply all our electricity needs all the time, but it will probably reduce our bills by 50%. We also feed back into the grid, but our RECs (Renewable Energy Certificates) have been bought by the installation company, further reducing our installation costs. We do get paid for the energy we feed back in though, even though it is less than what we pay for any grid energy we use.
We couldn't afford, and didn't have the roofspace for, any more than 12 panels.
THe one thing that did piss me off after it was installed though was to find out that if there is a powercut, our solar will shut down too. Once thebloke explained it, it made sense of course - because we feed back into the grid, they can't risk having power going through the lines when someone is working on them - but it was bloody annoying nonetheless, as it was one of the (obviously poorly researched) reasons for getting it! That and the ever-increasing electricity costs over here.