The solar light and heat that is harnessed using photovoltaics, solar architecture, solar heating and solar thermal energy is termed as solar energy. It is a form of renewable energy. Solar technologies can be characterized into two categories, namely active solar and passive solar. The former category involves the use of photovoltaic systems, solar water heating and concentrated solar power in order to harness solar energy. Passive solar technologies include building orientation towards the Sun, designing spaces with proper air circulation, etc. Solar energy, once harnessed, can be used for various purposes like water heating, cooking and water treatment, among many others. This book is compiled in such a manner, that it will provide in-depth knowledge about the concepts and applications of solar energy and solar technologies. It explores all the important aspects of solar energy in the present day scenario. This textbook will serve as a valuable source of reference for those interested in this field.