Self-shading : Sky Diffuse Shading Factor

Hi,

I have question regarding equation in section 9.2 from latest PV Technical Refference (www.nrel.gov/docs/fy18osti/67399.pdf).

1. What is Gd in equation 9.7 ? Is it equal to Id? so let's say Id is based on equation 6.4, then Gdh is equal to Ed (sun diffuse radiation)? Because if you compare the eq. 6.4 and 9.7, the angle adjustment (1+ cos (beta))/2 will be canceled out.
2. In the equation 9.11, Sdss is somehow proportional to Gsky,red, where in equation 9.9 Gsky,red is affected by number of rows. But as I concerned, the Sdss value will not change if the number of rows is changed. So what is this 'sky diffuse irradiance factor' in result?

Thank you
Daniel