Uncertainty Calculation Method for Photodiode Pyranometers

For all measurements, a provision of uncertainty for each measurement point is good practice. So far, a comprehensive methodology for uncertainties for rotating shadowband irradiometers (RSIs) has not been established, as the typical methods for calculating uncertainty are oversimplified, too time-consuming, or both when the instrument exhibits significant spectral dependence. The method presented herein allows the estimation of the uncertainty for each measurement provided by the RSIs. The methodology is tested on data from different climates, producing a comprehensive study focused mainly on measurements made with RSIs using photodiode pyranometers. The calculated expanded uncertainty for the RSI measurements matches the deviation from colocated thermopile sensors 95% of the time. Common uncertainty estimations of RSIs from the literature are confirmed using the comprehensive methodology in this article for the deviation and uncertainty calculations. The method is therefore well suited for the application in real measurement campaigns. In this study, photodiode pyranometers are also studied and the methodology for the RSI measurements also works for global horizontal irradiance measurements from photodiode pyranometers.

Automated summary

This study introduces a comprehensive methodology for estimating uncertainties in RSI measurements and successfully applies it to data from different climates. Through testing with data from varying climates, the method demonstrates good matching accuracy in RSI measurements.