Here is an interesting solar module I just found on EBay,
which is very flexible and you can put it onto round surfaces !
So if you have not a straight surface but need a solar cell to put
it around a curved track
check this out..It has 10 Watts...
http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=6062369967 (http://partners.webmasterplan.com/click.asp?ref=284148&site=1382&subid=&type=text&tnb=32&diurl=http%3A%2F%2Fadfarm.mediaplex.com%2Fad%2Fck%2F707-3922-3266-17%3Fmpro%3Dhttp%253A%252F%252Fcgi.ebay.de%252Fws%252FeBayISAPI.dll%253FViewItem%2526item%253D6062369967)