Dr. Marius Paulescu is an Associate Professor at the Physics Department of the West University of Timisoara (Romania). Since 2000 he has been active in the field of solar energy conversion, covering the whole range from solar radiation modeling and measurements to quantum physics applied to photovoltaic devices. His main scientific contributions are related to solar radiation estimation using statistical and fuzzy algorithms, state of the sky description and forecasting, development of solar radiation models based on air temperature data and modeling quantum solar cells. Dr. Eugenia Tulcan-Paulescu graduated in physics and mathematics from the West University of Timisoara (Romania), and earned a PhD in applied mathematics at the same university. Since 2005 she has been a lecturer at the Physics Department and was the person in charge of the Solar Platform project, including designing and building of the first Romanian station outfitted for systematic monitoring of solar irradiance on tilted surfaces, which has been in operation since 2008.Dr. Paul Gravila holds a PhD in Physics from the University of Zurich and is active at the Physics Department of the West University of Timisoara (Romania) in theoretical and computational physics. He covers a broad range from ab-initio methods in quantum solid state physics to elementary particle physics, is fluent with computer programming, numerical methods and symbolic calculus. Since 2008 he has worked in collaboration with the other authors of this book in the field of solar energy. Professor Viorel Badescu is a scientist presently affiliated with Candida Oancea Institute at Polytechnic University of Bucharest. His mainstream scientific contribution consists of more than 200 papers and 30 books related to statistical physics and thermodynamics, the physics of semiconductors, and various aspects of terrestrial and space solar energy applications. In addition, he has theorized on present-day Mars meteorology and Mars terraforming and on several macroengineering projects. He is a corresponding member of the Romanian Academy.