Installed 3.96KWp solar PV system in April 2010. It is working very well and has generated 10% more electricity than expected, possibly due to the fine summer weather, but also lots of winter sun. Obtaining the FIT was easy and have received two payments already with a further due in Feb 2011. I would highly recommend PV to anyone who can afford it who has a suitable south facing roof or piece of ground.
Read my case study here:http://www.sustainablecrediton.org.uk/Pages/Energy/Photovoltaics%20case%20study-%20Well%20Cottage.pdf
Do all the easy things - insulate the loft, draught proof doors and windows, don't use tumble dryers, change out old fashioned light bulbs, don't use stand-by, limit time standing under electrically powered showers. All these have cut 40% off our electricity bills in one year.