Estimating net short-wave radiation with the Bellani pyranometer

Two methods were developed by which daily net short-wave radiation $\text{(K∗)}$ can be evaluated from Bellani pyranometer readings. The first method involves a simple regression equation. The second method uses a physical approach taking into account the effect of the Bellani's geometry on its response to direct and diffuse radiation throughout the day. Both methods, when tested on experimental data, tended to underestimate the measured $\text{K∗}$, the regression approach exhibiting a higher variance of the error.