This book is my first edition of the books on thin-film deposition for Photovoltaic cell applications. In other books much concentration is on thin films classification, deposition and characterization techniques but in this book more has been added on solar cell theoretical approaches materials currently in use and those under investigation using modern deposition and their applications on solar cells. Current trends in solar technology is also highlighted. While thin film fundamentals have not changed, the industry has grown enormously. Included is an introductory Quantum Mechanics followed by mathematical approaches to thin film Semiconductor materials theory and applications which describes electronic transitions and energy changes that occur in thin films as they undergo growth and applications. In addition, many new manufacturing processes like chemical vapour, spray pyrolysis and Chemical Bath Deposition Techniques have become mature and are discussed. More on Solar Cell fabrication, Solar Cell operations, Solar cell modules and Solar utilization methods are further discussed in detail.