The photovoltaic performance under operating outdoor conditions is affected by the variability of the solar spectrum. The spectral distribution is quantifiable using the average photon energy (APE). In the present study, we characterize the spectral distribution in a low-latitude location such as Lima-Peru through a decade of simulated solar spectra obtained on demand from the National Solar Radiation Database and taking as a reference one year of ground-based experimental data following the decade of theoretical spectra. This characterization utilizes annual and monthly averages of irradiance-weighted APEs. The results indicate a difference of only 0.2% between the average annual APE for the decade and the annual ground-based experimental APE. Additionally, the theoretical monthly APEs for the decade show a seasonality consistent with our experimental data for the summer months but not for the winter months.