When the leaves or panels of the doors are made wholly or partly of glass or other transparent materials, solar radiation contributes to the heat inside the building. This is an effect which is generally favourable in winter and unfavourable in summer.
The solar factor is the relative amount of the total solar radiant heat energy entering the building through the glass.
In general, the value of the flow of heat by solar radiation depends also on the geographic latitude and the orientation of the elevation. The model takes these factors into account in average terms.
In real building environments, there are other external factors like the presence of shadows due to neighbouring buildings, the existence of parasols or solar protection elements, etc.
Since access doors are at levels close to ground, the influence of the solar factor is lower than for windows, and in general is of a lower order than other factors, even more so when looking at the effect over the whole year.