This paper focuses on the concentration dependent spectroscopic and NIR UC properties of Er3+-doped tellurite glasses with an aim to be utilized for solar cell applications. Ellipsometric studies are performed on the samples and the refractive index and Abbe number are evaluated. Judd–Offelt parameters are investigated and used for the evaluation of radiative properties. The luminescence properties are derived from the emission spectra for the 4I13/2-4I15/2 transition. Decay curves are recorded for the 4I13/2 level of Er3þ ion and their lifetimes are estimated. The UC was measured by exciting at 1520 nm and a possible mechanism is proposed to explain the radiative and non-radiative processes.