A single clear sheet of 4 mm glass has the perfect daylight transmittance factor of 0. This chapter examines the fundamental role of glass materials in photovoltaic (PV) technologies, emphasizing their structural, optical, and spectral conversion properties that enhance solar energy conversion efficiency. Despite the abundance of solar radiation, significant energy losses occur due. Sunlight contain wide range of solar rays some visible and some not, called Spectrum. Transmitted in space in a wide range of wavelengths and heat intensity. Calculation based on the optical. At the value of 60° of the incidence angle, the transmission of the solar spectrum is significantly attenuated.