ABSTRACT
This chapter provides a brief summary of the importance of spectral distributions to renewable energy applications, an overview of the principles behind various complex and simple spectral models, and the equations behind one of the most simple and straightforward spectral models. The combination of the variability in natural spectral distributions and spectral response functions presents significant challenges in designing, evaluating, and predicting the performance of renewable energy systems, including daylighting, photovoltaic (PV) systems, and optical properties of materials in general, especially in outdoor applications. Architects and illumination engineers rely on the CIE for many technical aspects of their design needs and with respect to replacing artificial lighting with daylighting. Highly detailed descriptions of the SMARTS model are provided in Gueymard and others. The approach is essentially a more sophisticated application of parameterized models of Bird and others, but using transmittance functions with additional terms for trace gases.
