Calculation of solar radiation on a surface with any orientation and inclination according to VDI 6007-3

Engin Bagda, www.heizen-co2-sparen.de

The code SunSimulation_VDI_6007_3.py calculates the daily and yearly solar irradiance on a surface with any orientation and inclination for a given place, located by its longitude and latitude. The code is based on standard VDI 6007-3:2015, confirmed 2021 “Calculation of transient thermal response of rooms and buildings – modelling of solar radiation”. This code differs from DIN 5034-2 “Daylight in interiors-Principles” explained in https://github.com/Heating-and-cooling/sun_daily in the calculation of the amount of diffuse radiation to inclined surfaces.

Figure 1: Turbidity factors according to Linke over the year with a measured minimum value at day number 181

To calculate from horizontal diffuse radiation to a surface with any orientation and inclination VDI-6007-3 uses conversions factors R. These differ for clear and overcast skies. For skies with mixed clouds is a coefficient SSW for solar probability is used. SSW can be between 1 for totally clear sky and 0 for totally overcast days. In the code SSW can be changed. In average for the year a value of 0.7 for SSW is appropriate. The code generates an Excel file SunRadiation.xlsx. This includes a sheet Solar_radiance for the solar radiation on a chosen day to different oriented surfaces with different inclinations, calculated in steps of 5 minutes (see figure 2).

Figure 2: Solar radiation at day number 180 (30.June) for the place Mannheim with SSW: 1 and TF: 1.9

In the sheet ‘Daily-Values’ are the daily values for the solar radiation on different oriented surfaces with different inclinations (see figure 3).

Figure 3: Daily solar radiation for the place Mannheim with SSW: 1 and TF: 1.9

For more information to the code SunSimulation_VDI_6007_3.py see: Berechnen der solaren Bestrahlungsstärke auf beliebig geneigte Flächen in Anlehnung an VDI 6007-3 - Heizen-Kühlen-Sparen (heizen-co2-sparen.de)