By applying Eu3+/Tb3+-doped phosphate glass as photovoltaic (PV) precursors, the performance of conventional amorphous-silicon and multicrystalline silicon (mc-Si) PV solar cells was improved. Rare-earth glass absorbs light at ultraviolet bands and subsequently emit light at visible bands. The shorter wavelength of the solar radiation is downshifted to longer wavelengths. Hence, the photon-to-current efficiencies (PCE) of a/mc-Si cells are higher, because the emitted photon matches with a higher spectral sensitivity region of a/mc-Si cells. For a phosphate glass, Eu3+/Tb3+ placed on top of an actual a/mc-Si cell experiments and simulations both showed maximum relative increases of 3.57% and 6.26% in PCE. The real PCE enhancement can be proved, thus the potential prospects of Eu3+/Tb3+-doped phosphate glass on the PCE of PV modules can be looking forward in the near future.