This model calculates the input of heat and visible light into the room due to solar irradiation. Therefore it uses the calculations of VDI 6007 part 3. It considers the correction values for non-vertical and non-parallel radiation incidence.
VDI. German Association of Engineers Guideline VDI 6007-3 June 2015. Calculation of transient thermal response of rooms and buildings - Modelling of solar radiation.