To what extent does the radiation of a solar simulator meet a reference sun? A quantitative approach

Solar simulators generate radiation which should simulate a defined reference sun as perfectly as possible, and most important is the fitting to the spectral distribution. So far, the fitting is described verbally only, e.g. in standards concerning artificial weathering, and the user has to decide for himself whether the spectral distribution (E lambda) indicated by the producer of the solar simulator agrees well enough with the reference sun for his specific application. Occasionally, the classification describes the fitting to a wanted reference sun only insufficiently (e.g. qualification approvals for photo voltaic modules). This paper deals with a procedure for the determination of factors characterising the grade of fitting in quantity. For various solar simulators which are commercially available (e.g. for artificial weathering tests or design qualification tests), characteristic factors for different wavelength ranges are indicated, and a proposal is made for a classification regarding the grade of fitting of the spectral distribution of solar simulators to a defined reference sun. As examples of characteristic factors regarding action spectra with especially distinct wavelength dependence, characteristic factors for the UV erythema and the C=O formation of PE are given. (C) 2012 Elsevier Ltd. All rights reserved.