seems like a pretty neat idea
i think the sort of panels ya are gonna want to power say a couple of 600w hps lights are gonna be quite expensive and very big in size too
a bit of research will help alot
here is a site for you to look at
http://www.unlimited-power.co.uk/Catalogue.html
and if you wanna try making ya own here is another link
http://www.bigginhill.co.uk/solar.htm
hope this helps m8
cheers all