Spectral measuring condition for solar cell

In order to evaluate solar cell, spectrum of spectral response & spectral irradiance of the incident light are multiplied and integrated. The wavelength resolution of the monochromator influences the spectral waveform so much that the evaluation would be influenced. We investigated the way to find the proper wavelength resolution for the evaluation from the wavelength dependence of the spectral shape of solar cell, solar light and transmittance of monochromator system. The wavelength resolution of the monochromator system should be higher than the inverse of the highest frequency component of the Fourier transformed spectral response. At the same time, the wavelength resolution should be high enough so that the transmittance of the monochromator system is considered to be constant within the wavelength area which is the same as the wavelength resolution.