Solar Energy: Principles and Applications

34 The ever-increasing demand of energy for development of the society is fulfilled by a variety of energy sources. Large-scale energy utilization has led to a better quality of life and faster all-round development; it has also generated many critical problems. The most prominent of these is the harmful effect on the environment in various forms leading to global warming and climate change. At the same time, the fossil fuel resources are also fast depleting due to over exploitation. Therefore, it is worth to explore the alternative energy sources, systems, and technologies for sustainable development, if not fully but at least to substitute an appreciable amount of conventional energy to mitigate the harmful effect to some extent. Other than fossil fuels, nuclear and large hydropower, there are a number of sources of energy which have started contribution in a small way to the world’s present energy demand and supply scenarios. These include energy sources like wind energy, small hydro, photovoltaic conversion, biomass, tidal, geothermal energy, and solar thermal power plants. Among the renewable energy sources, solar energy plays a vital role both for its thermal and photovoltaic applications. In this chapter, the authors have focused on the thermal conversion route of solar energy with respect to solar energy collection devices, working fluids, solar thermal energy storage, etc.