For a window with an overhang, this model outputs the fraction of the area that is exposed to the sun. The models can also be used for doors with an overhang.
The overhang can be asymmetrical (i.e. wR ≠ wL is allowed) about
the vertical centerline of the window. However, the overhang must
completely cover the window, i.e., wL ≥ 0 and wR
≥ 0. wL and wR must be measured
from the respective corner of the window.
The figure below shows the parameters.

The surface azimuth azi is as defined in Buildings.Types.Azimuth.
The model assumes that
The implementation is explained in Buildings.HeatTransfer.Windows.BaseClasses.Overhang.
lat because the latitude is now
obtained from the weather data bus.wL and wR to be
measured from the corner of the window instead of the centerline.
This allows changing the window width without having to adjust the
overhang parameters.