Hourly Shading file for computation of production numbers(KWh)

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Muhammad Farhan
Hourly Shading file for computation of production numbers(KWh)

I am using the SAM SDK for finding the production numbers using our own calculated Solar Access. Then problem that i am facing right now is that the production number are different on SAM tool and SAM SDK using the same weather file and same data. I would like to know that the way your are following for the computation of solar Access (both monthly and Annually) using the hourly based shade CSV. Because when i am putting my solar Access in your SDK then the results are pretty close when the solar access is greater then 90% and the difference between production numbers increases as solar access < 90% using the SAM SDK and SAM tool.

Is there any way to put our own hourly based shade CSV file in your SDK? as we do in SAM tool.
or any API for this!

Best Regards,
Farhan

Paul Gilman

Dear Farhan,

First, please make sure that you are using the same version of SSC in your API calls that SAM is using. To see the SSC version number for SAM, open the Help browser and click About.

It is possible that the inputs in SAM are not identical to the inputs in your code. You can press the Shift-F5 key in SAM to generate an LK script that lists all of the SSC input variables and their values.

You can use the subarray1_shading variable to read your own shading data. For example, if you have an 8760 column of beam shading losses stored in a variable called shading_losses for Subarray 2, you would assign it as follows (in LK script):

var( 'subarray2_shading:hourly' , shading_losses ) 

Similarly, you can assign month-by-hour shading factors to subarray1_shading:mxh, and azimuth-by-altitude losses to subarray1shading:azal. Note that the number suffix to subarray determines which subarray the shading losses apply to.

Best regards,
Paul.

Muhammad Farhan

thanks Paul for your reply.
I am working on php (ubuntu 64 bit) and i am using the pvwattsv5 module for my project.
I am adding a single line to my code and i have seen no impact on production number after adding or removing this line.

line: "sscphp_data_set_number($dat,"shading:hourly", [ 0, 0, 0, 0, 0, 100, 100, 100, 100, 75, 0, 0,...,75, 100, 100, 0, 0, 0, 0 ]);"

Best Regards,
Farhan

Paul Gilman

Dear Farhan,

Have you been able to change the values of other SSC variables in your PHP script? The shading:hourly variable is a one-dimensional array of 8760 percentage values, so if you correctly assign the values, you should see a difference in outputs like gen and annual_energy.

Best regards,
Paul.

Paul Gilman

Also, because the shading:hourly variable is an array, you should use the sscphp_data_set_array() function instead of the sscphp_data_set_number() function to assign it a value.

Best regards,
Paul.

Muhammad Farhan

Thank you paul for your reply,
I have already implemented this feature.
I have other questions as well.
Can you give me your email? so that i will discuss it with you.

Muhammad Farhan

The results of SAM SDK and SAM tool are now matched. Everything is working. I need to know few more things.

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