Evaluating solar ramp rate correlations by simple radiation and wind measurements

Abstract

The stability of photovoltaic (PV) energy output is critical to power supply and is a crucial factor for the reliability of power supply systems but is significantly influenced by the unpredictable shading caused by clouds. Assessing the variability of solar radiation across a spatially dispersed PV fleet can be challenging, as it is usually lower than that taken by routine measurements at a singular, localized point. This study refines the previously developed spatial radiation variability model by depicting the attenuation mode of solar irradiance correlation across spatial distances and considering the differences in the along-wind and cross-wind directions under various weather and solar radiation conditions. These modes are further connected to the variables that properly depict the weather conditions and are straightforward to measure. The data being adopted in developing and validating the model are collected from 17 pyranometers over a 0.56 km2 area for about half a year with a 1-s resolution. The model's performance, with a percentage root-mean-square error that surpasses isotropic models by 2.42 %–10.6 % for solar ramp intervals ranging from 5 to 240 s, underscores its accuracy and potential for optimizing the integration of PV fleets into power grids.