Hi,
We recently had Solar Panels installed and whilst my husband was researching he came across a website created where people input their actual data from their systems!
It gives you an excellent indication as to what different size systems in all different areas will give you.
I shared this link with Raleighfarm who is currently looking at getting Solar Panels, she also found it very helpful and suggested I add it to the Eco Living section!
Hope you find it helpful too
http://pvoutput.org/list.jsp