In this work, we evaluate the impact of solar spectrum down-converter (DC) on an energy yield of solar cells worldng in real world meteorological conditions. For this purpose, a simple model of PV device with a down converting layer is used, with inputs (spectra, irradiance, temperature) taken from the public NREL database for their outdoor test facility. The model assumes ideal external quantum efficiency (EQE). The analysis showed that in these conditions the energy yield increase from the use of DC system is 23.64% which is bigger than improvement due to DC calculated for the standard test conditions (20.1%). This effect is more profound in summer (24.8% for June-August) than winter months (22.1% for December-February). The average photon energy (APE) turned out to reasonably well reflect the overall impact of the DC layer on the energy yields with R-2 = 0.96. The primary conclusion is that the impact of spectral converters on PV device performance should be analyzed not only in the standard test conditions as in the real operating conditions the result of spectra converting layer may turn out substantially better, lowering the bar for commercialization and broad application of such layers.