Physics of Solar Energy discusses the fundamental concept of solar energy, solar cells and nano fluids. It also includes the technologies used for the conversion of solar to fuels and performance assessment of nanofluids in the solar energy and thermal properties of carbon black aqueous nano fluids for solar absorption. This book also discusses about ab initio design of nanostructures for solar energy conversion, design of inp nanowires for maximal solar energy harvesting, optical simulations of p3ht/si nanowire array hybrid solar cells, dual effect of tio2 and co3o4 co-semiconductors and nano-sensitizer on dye-sensitized solar cell performance and spectrum splitting for efficient utilization of solar radiation: a novel photovoltaic–thermoelectric power generation system. It also provides the reader with the fundamental insights of solar energy and its conversion to fuels so as to get better understanding of designing nanostructures for the conversion of solar energy and the effect of external applied electric field on the thermodynamic efficiency of the silicon solar cell and calcination temperature on the properties of czts absorber layer.