Solar energy-based technologies have seen remarkable development in the last decades. This is observed all across the world. The concerns related to cost and availability of fossil fuels, effects of climate change due to use of fossil fuels are the primary drivers behind the usages of these technologies. With such motivation, several research groups around the world are working in the field of solar energy. Since this field is quite diverse, it includes academicians of diverse background such as physics, chemistry, materials science, mechanical engineering, electrical engineering etc. This monograph is an effort to present the collection of such effort with an aim to present the developments at the system-level as well as the challenges and opportunities that are present at the technical level. It includes chapters covering the following themes—overview of energy usage in developing countries, solar thermal systems (heating and cooling), energy storage, and solar cells. © 2020, Springer Nature Singapore Pte Ltd.