Global hor radiation and global hor illuminance

Hi¡…I created an epw with data that I obtain from a weather station in my home (temperatures and relative humidity) and radiation and illuminance by a model found in papers of Muneer(2004) and Collares Pereira(1979). With the model needs the min/max temperatures, latitude, longitude and some solar geometry.

I discovered that LBtools respects muy values of direct and diffuse radiation and illuminance (I saw that in the panel are the same hourly values).

Is there a document that explains how LBtools calculates the global hor radiation and global hor illuminance?