Coatings of fluorescent coloring agent (FCA) an the glass of a solar cell module were proposed to increase the energy conversion efficiency of the cells by preventing the layer of glass and filler From absorbing light at wavelengths below 400 nn. The FCA coating showed no reduction in reflectivity at wavelengths longer than that for excitation, because the refractive index of FCA was close to that of glass, Le., 1.5 Yellow FCA absorbed light at wavelengths below 500 nm as the excitation light and emitted Light at wavelengths longer than 420 nm, which are not absorbed in the layer of glass and filler. Thus the change in wavelength through the yellow FCA coating yielded a 6% increase in the energy conversion efficiency of the solar cell.