Evaluating the value of subordinate standard spectra

Abstract

The purpose of this work is to investigate if a subordinate reference spectra in addition to the main standard spectra for different atmospheric conditions can enable an intuitive and more direct comparison of solar energy components. The main criterion for the evaluations of the value of the spectra is the change of the plant components efficiency with the spectra. As the number of subordinate spectra should be as small as possible and only as high as needed the spectra is investigate for similarities. The applicability of the subordinate standard spectra and the possible improvement of quick product comparisons is tested and discussed based on time series of spectral data from five exemplary sites that are of interest for solar energy plants. These time series are created from ground measurements of broadband solar irradiance, aerosol optical depth, perceptible water vapor and other auxiliary parameters. A model to derive DNI spectra based on this input is enhanced so that also GTI can be derived. If the intuitive selection of a subordinate spectrum based only on the average atmospheric parameters for the example sites leads to more accurate estimation of the components efficiency (e.g. responsivity, absorptance, transmittance etc.), this suggests that this concept has some practical value. On the other hand, if this is not the case for some of the exemplary sites, it proofs that there are sites where this concept or at least the suggested 8 subordinate spectra are not applicable.