Table 3
Description of DNI-variability classes based on Schroedter-Homscheidt et al. [38] and Nouri et al. [39]. Each DNI variability class indicates a certain sky condition and a specific level of variability.
| Class | Sky conditions | Variability |
|---|---|---|
| 1 | Mostly clear sky | Low |
| 2 | Almost clear sky | Low |
| 3 | Almost clear sky | Intermediate |
| 4 | Partly cloudy | High |
| 5 | Partly cloudy | Intermediate |
| 6 | Partly cloudy | High |
| 7 | Almost overcast | Intermediate |
| 8 | Mostly overcast | Low |
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