This book deals with existing technologies of solar energy conversion as well as novel  methods under consideration in academic and commercial R&D sites. The experimental results presented in the work are well crafted by both analytical and first-principle numerical simulations. The book highlights the real potential for economically justified use of solar energy at every household and/or commercial solar farms. The ever-improving methods of thin-film epitaxial growth combined with a better understanding of the sun light absorption and antireflection are highlighted.  While there was a period when the material quality was considered to be cornerstone of the conversion efficiency followed by substantial efforts to optimize multiple-cell architecture, it became clear that many old ideas such as variable band gap, multi-junction intrinsic region, as well as solar tracking mechanisms offer new possibilities for improved harvesting of energy. Amplifying the importance of materials selection efficient design of the photo-voltaic elements various aspects of the production cost and the impact on the environment are discussed. In addition, the eligibility of the proposed production technologies in the current photovoltaic market are evaluated and confirmed.