1. You can find detailed descriptions in textbooks like Iqbal's 'Introduction to solar radiation' or Duffie & Beckman 'Solar Engineering of Thermal Processes', and in https://www.researchgate.net/publication/236314639_Direct_and_indirect_uncertainties_in_the_prediction_of_tilted_irradiance_for_solar_engineering_applications 2. There have been many papers investigating different avenues: https://doi.org/10.1016/0038-092X(79)90076-8 https://doi.org/10.1016/0038-092X(66)90025-9 https://doi.org/10.1016/0038-092X(88)90002-3 https://doi.org/10.1016/S0360-5442(00)00003-7 https://doi.org/10.1016/0038-092X(80)90349-7 https://doi.org/10.1016/0038-092X(93)90145-E https://doi.org/10.1016/0038-092X(80)90394-1 https://doi.org/10.1016/0038-092X(84)90007-0 https://doi.org/10.1016/0038-092X(78)90074-9 https://doi.org/10.1016/0038-092X(77)90027-5 https://doi.org/10.1016/0038-092X(82)90281-X https://doi.org/10.1016/0038-092X(81)90161-4 https://doi.org/10.1016/S0038-092X(99)00009-2 doi:10.1016/j.solener.2005.09.008 https://doi.org/10.1016/0038-092X(80)90490-9 https://doi.org/10.1016/0038-092X(93)90145-E https://doi.org/10.1016/0038-092X(95)00058-Y https://doi.org/10.1016/0038-092X(85)90103-3 http://dx.doi.org/10.1016/j.solener.2013.01.015

Chris

dear Chris

I still have a copy of the book here and am gladto hear from an expert it is apparently still up-to-date

Harry ten Brink

Dear Mart Dave, I am dropping here the link of paper, it might be helpful for you. Please check the link.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.tandfonline.com/doi/pdf/10.1080/07055900.1986.9649238&ved=2ahUKEwjLtZaF_bXsAhXBxYUKHbwJA3sQFjANegQIARAB&usg=AOvVaw2zz_4QWIsmaZ2JxeOMWskV

Here it is downloaded

Abderrahim Habchi Thanks Sir, I really appreciate this, i will download it right away and read through it

Chris Gueymard Thanks so much sir, I will go through them sir.

Meer Zafarullah Noohani Thank you sir. I will download it right away

Thank you, Chris!

Regarding the net radiation you can also see the formulation used in the aermod atmospheric model available at (page 16):

https://www3.epa.gov/scram001/7thconf/aermod/aermod_mfd.pdf

As mentioned above, there is a lot of literature on this topic. I also have a publication on this topic (Innov Ener Res 2019, Vol 8(1): 223 ) and below is a fragment from this work.