The use of the upconversion emission in Tm3+ doped glasses for solar applications has been analyzed. The Tm3+ ions, that absorb photons from the near infrared range, perform an energy transfer upconversion process from the F-3(4) intermediate energy level to the H-3(4) excited state followed by the radiative emission of photons at 800 nm, which correspond to the H-3(4) -> H-3(6) electronic transition. These photons can be absorbed by a silicon solar cell and hence be used in the generation of photocurrent. From the analysis of the rate equations that describes the emission of the 800 nm photons, the dependence of the External Quantum Efficiency with the solar concentration value has been obtained. (C) 2015 Elsevier B.V. All rights reserved.