This section provides a concrete example of how a comparative performance as­sessment study can be conducted when a large number of models is involved. In the present case, a rather exhaustive literature survey provided a list of 35 clear – sky broadband irradiance models that can predict instantaneous or short-term (e. g., hourly) direct and […]

Many of the issues discussed above become much more noticeable and complicated for validation of models based on satellite input data. The questions of temporal and spatial consistency are particularly vexing, as satellite data, while uniform, are usu­ally sparse in time compared to surface observations. Spatial concerns are an even greater problem, since surface observations […]

With physical and empirical model evaluation of single or multiple models, an im­portant problem is that, often, the performance evaluation units and temporal reso­lution used in the new evaluation are different from those in the original validation. This is a much larger problem for satellite-based model evaluation, discussed briefly in the next subsection. For example, […]

Independent evaluation of models based on input parameters and measured data for different sites is prevalent in the literature. One or more model is evaluated with one or more new and independent validation data sets.

One informative segment of model performance is the comparison of model ele­ments or functions to previously-developed similar model components. Examples include so-called “simple” broadband or spectral transmittance models. These types of models were briefly mentioned in Sect. 4, and described in Eq. (20.4). Compar­isons of individual transmittance functions from some similar models are detailed elsewhere […]

Solar radiation model performance is usually carried out from two different perspec­tives. First, the assessment of models made by their developers is usually referred to as validation, as discussed in previous sections. Secondly, models can be evaluated by testing against independent data sets, usually by authors independent from the model development.

The solar radiation literature is rich in validation reports of new, isolated models, or in performance assessment studies of similar models being intercompared. But, readers or users might ask, what is the significance of all these results? Interest­ingly, from a philosophical perspective, it has been boldly postulated that “ Verifi­cation and validation of numerical models […]

Most generally, the performance of various models is evaluated against a single dataset, in the aim of selecting the best performing model for this particular dataset, and by extrapolation, for the climatic conditions represented by the dataset. Using qualitative information from plots such as Figs. (20.3)-(20.5) would be too diffi­cult or subjective for this task. […]