This course deals with the Radiation outside the earth atmosphere, solar constant, spectral distribution, Atmospheric attenuation, Direct and diffuse radiation, measurement and characterization of solar radiation, laws of Plank and wien, Black and Gray bodies, spectral dependence of absorbance, emittance and reflectance, greenhouse effect, convention between sloping plane surfaces, suppression, Wind, Flat and concentrating collectors, spherical, parabolic, Fresnel and mixed, Thermosyphon-optimal flow rate, Photovoltaic cells, Desalination.