Are you interested in PV's ? If so have I got a site for you. The pictures below show an 8 vol. and article set that I got from Sandia Labratories. a leading American energy research lab. They shipped them to my door free of charge books and shipping. Boy hard to beat that. That was back in 2009, nowadays you can download all of these books and much more free of charge at the following link:
http://energy.sandia.gov/energy/renewable-energy/solar-energy/photovoltaics/pv-resources/publications/As you can see from the book titles the subject is well covered.
Cheers
CB