Sandia Library Modules mounting configuration

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nino
Sandia Library Modules mounting configuration

Hello,

I am using SAM to perform Flat Plate PV analysis with 'Sandia PV Array Performance Model with Module Database'.
Each module from Sandia Library comes with predefined irradiance/wind speed/temperature factors: 'a' and 'b' and 'dT'.

I am wondering: is it possible to identify the mounting configuration of the Sandia module, based on its 'dT' value?
This is basically my question.

I am fully aware that I can somewhat define the mounting configuration of the module by picking it from the 'Module Structure and Mounting' drop list. But I do not want to do this. I would like to use only those 'a', 'b' and 'dT' Sandia Modules Library values which are specifically set for that module. Not manually enter them, nor use those default ones defined by 'Sandia Cell Temperature Model'.

I am also aware of the fact that 'CEC Performance Model with Module Database' does much better job in terms of setting custom mounting configuration. But I do not want to use CEC, I would like to use Sandia Model.

Please let me know, if my question was not clear enough.
Basically, I am trying to predict the mounting configuration of Sandia Library's module, based on its 'dT' value.
https://s6.postimg.org/n7feft8ld/delta_T.jpg

Can something like this be predicted:

dt is 2 or 3: Open rack
dt is 1: Close roof mount
dt is 0: Insulated back

?

Thank you for the reply.

Paul Gilman

Hello,

Yes. The approach you describe makes sense, and is consistent with the description of the dT parameter in the King (2004) description of the Sandia module model.

Best regards,
Paul.

nino

Thank you for the quick reply Paul!

I was wondering if I could ask another, just a bit different question:
In SAM application, I am looking at 'CEC Performance Model with User Entered Specifications'.
In 'SAM Photovoltaic Model Technical Reference.pdf' I've read that it is based on: Dobos A.(2012)
“An Improved Coefficient Calculator for the California Energy Commission 6 Parameter Photo-voltaic Module Model".

Is it possible that some similar coefficients calculator exists for Sandia Performance Model?

If not, then how are values from Sandia Modules Library .csv file generated?

Paul Gilman

Hello,

The Sandia module model differs from the CEC model in that the Sandia model uses equations with coefficients that must be determined empirically from measurements taken during module testing. Those coefficients cannot be determined mathematically without the test data.

This empirical approach is described in King (2004) "Photovoltaic Array Performance Model."

Best regards,
Paul.

nino

Thank you once again for the clear explanation Paul.
Regards, Nino.

nino

Paul, just one more question please:
I took a look at your 'Libraries' page on sam.nrel.gov website:
https://sam.nrel.gov/libraries

It contains Sandia Modules Library from 2015/6/30.

Does this mean that the Sandia Modules Library hasn't been updated since 2015?
If not, then are there plans to update this library?

I am currently not able to check this, but could it be that the newest SAM 2017.1.17 software comes with updated Sandia Modules Library?

Paul Gilman

Hello,

The libraries we posted on the SAM website are from an earlier version of SAM, when we used a special text format for equipment libraries that were difficult to read. Since then, in more recent versions of SAM, we changed the library file format to a more straightforward comma-separated (CSV) format that is easier to read and work with.

You can find the latest libraries in the libraries folder of your SAM installation. For more details, see the Libraries topic in the SAM Help system.

Best regards,
Paul.

nino

Thank you once again for the detailed reply Paul.
I just downloaded the SAM 2017.1.17 Windows version and its 'Sandia Modules.csv' file from 'SAM install folder\libraries' folder is literally the same as the 'sam-library-sandia-modules-2015-6-30.csv' you have on your website:
https://sam.nrel.gov/libraries
The 'Sandia Modules.csv' file is dated as: 25th of November 2015.

Does this mean that maybe the OS X or Linux versions of SAM software have different (updated) 'Sandia Modules.csv' files?

Paul Gilman

That means that we have not received an update for the Sandia library since then.

Best regards,
Paul.

nino

Thank you once again Paul.
Regards,
Nino

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