Gaussian distribution of average photon energy and spectral gain and loss of several-type photovoltaic modules at different outdoor sites around the world

Distributions of actual average photon energy (APE) at several outdoor locations around the world are investigated and can be characterized using Gaussian distribution with average APE (mu) and standard deviation (sigma) values. For the comparison among different outdoor sites, their APE distributions must be calculated based on the measured solar spectra in the same wavelength range. The method to convert APE values based on different wavelength ranges into those based on same wavelength range is consequently proposed. It is shown that spectral gain and loss (G&L) of different-type photovoltaic (PV) modules calculated from actual APE distribution and its Gaussian fitted distribution are almost similar. General G&L contour maps of the different type PV modules as functions of mu and sigma values are then calculated. These contour maps readily allow us to quantitatively evaluate various-type test PV modules at several outdoor locations around the world, when the mu and sigma values are known.