Dear Ali 

There are different solar radiation models to predict DHI and DNI including ASHRE and Duffi many of them are described and validated in the following article:

http://www.sciencedirect.com/science/article/pii/S019689041500285X 

I hope it will help you 

best wishes 

visit this site  set your country location and direction 

http://solarelectricityhandbook.com/solar-irradiance.html

Hi,

Thanks for your reply. But I am looking for the equations so that I can implement them in my code.

 i hope it will help

Dear MM Ali: find attached an article contains the required equations. Also, you will find more information in my books as follows:

1.     Hussein A. Kazem and Tamer Khatib, “Photovoltaic Power System Prospective in Oman, Technical and Economical Study”, 1st Edition, ISBN: 978-3659372957, LAP LAMBERT Academic Publishing, Germany.

 2.     Hussein A. Kazem, “Renewable and Sustainable Energy, Principles and Applications”, 1st Edition, 978-3-659-46238-2 LAP LAMBERT Academic Publishing, Germany.

 3. James Watson, Lawrence Kazmerski, Dave Renne, Hussein A Kazem, K. Sopian, Nader Al-Bastaki, Dr Shaker Haji, Mohd. Yusof Othman, Winfried Hoffmann, Stefan Krauter, D. T Swift-Hook, and Tony Book “Practical Photovoltaic for Sustainable Electricity and Buildings”, Editor: Prof Ali Sayigh, 1st Edition, Springer 2017, ISBN10 3319392786, ISBN13 9783319392783, Switzerland.

𝐼𝑠𝑢𝑟=((𝜏0−𝜏0𝜚𝐵−𝜏0𝛼𝑤−𝜏0𝛼𝑎𝑒𝑟))/([(1−𝜚𝐺)+(𝜚𝐺𝛼𝑤−𝜚𝐺𝛼𝑎𝑒𝑟)]) I TOA,

Dear Dr. Hussein,

Thanks for your message. I sent you a mail. Please reply.

Regards

Ali

As far as I understand future IEC 61853-3 & IEC 61853-4 intend to define this: http://www.iec.ch/dyn/www/f?p=103:23:2836371872084::::FSP_ORG_ID,FSP_LANG_ID:1276,25

Peter

http://www.solar-estimate.org/?page=solar-calculator

Books like those issued by "G.N. Tiwari and "B.H. Khan" include a sequential methodology that may conduct your estimation. Regards

Dear Ali 

There are different solar radiation models to predict DHI and DNI including ASHRE and Duffi many of them are described and validated in the following article:

http://www.sciencedirect.com/science/article/pii/S019689041500285X 

I hope it will help you 

best wishes 

 Hi, 

I share to my students the following information (http://pveducation.org/pvcdrom/2-properties-sunlight/solar-radiation-earths-surface) to elaborate quick estimation of solar radiation in a surface. The relevance of this website is that includes interactive examples so you can compare your results with previously coded information. However, there are other factors that are relevant and are not considered in this assessment. 

Thank you very much Alexis for the information. The information you share with your students would be certainly educative to me.

Can the two softwares freely downloadable?

Can you please share you email id so that I can share some of the doubts/problems I have been facing?

Basim: 

The paper referred by you is very informative. I have two more questions: 

1. Please provide a link to down load the two software. I googled for UDFFI (correct spell?) software but could not locate. 

2. Please answer my second question of estimating power from GHI/DNI.