
286 Principles of Sustainable Energy Systems
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In summary, monthly averaged, daily solar radiation on a surface is calculated by rst
decomposing total horizontal radiation into its beam and diffuse components using
Equation 5.53 or 5.54. Various tilt factors are then used to convert these horizontal compo-
nents to components on the surface of interest.
5.6.3 Daily Solar Radiation on Tilted Surfaces
Prediction of daily horizontal total solar radiation for sites where solar data are not measured
can be done using the Angström–Page model. Instead of monthly values, however, daily val-
ues are used for percent sunsh ...