CEC Modules Library mounting configuration

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CEC Modules Library mounting configuration


Paul Gilman recently helped me with a similar issue related with default mounting configuration of the Sandia Modules Library. This is the topic:

I am wondering if something similar can be done with the CEC Modules Library: can one guess the mounting configuration of the module from CEC Modules Library?

When using SAM software I noticed that modules from CEC Modules Library can use NOCT cell temperature module which enables different mounting configurations based on the length of the standoff. But this is an alteration of the chosen module from the Library. What about the module's default mounting configuration? Can it be known/guessed?

When CEC Modules Library .csv file is opened there is a "BIPV" column with values "Y(es)" and "N(o)".
This is sufficient do determine whether the module is BIPV/Insulated back or not.
But what if we would like to know whether the module from the library had Open rack or Close (flush) roof mounting configuration? Is it possible to know this?

I hope my question is not too confusing. If it is, please let me know, I will try to redefine it.

Thank you in advance for the reply.

Paul Gilman


When you choose a module from the CEC library, SAM populates the inputs in the "Module Characteristics at Reference Conditions" and "Additional Parameters" boxes on the Module input page from the CEC module library file that comes with SAM. Those parameters are provided to us by the California Energy Commission.

The mounting specifications for determination of the T_noct parameter for BIPV modules are described in Appendix B of the California Energy Commission "Guidelines for California's Solar Electric Incentive Programs (Senate Bill 1)."

The SAM inputs for the NOCT temperature model are independent of the module parameters. Therefore, it is possible to choose a module from the CEC library indicated as a BIPV module and with T_noct measured according to the CEC BIPV specifications, and choose the rack-mounted option for the temperature model.

SAM's NOCT temperature model adjusts the T_noct value according to the option you choose:

Building integrated, greater than 3.5 in, ground rack mounted: T_noct + 0 (no adjustment)
2.5 to 3.5 in: T_noct + 2
1.5 to 2.5 in: T_noct + 6
0.5 to 1.5 in: T_noct + 11
Less than 0.5 in: T_noct + 18

For a detailed description of the NOCT cell temperature model, see Section 9.7 of the SAM PV reference manual, which is listed with other useful references on the Performance Model Documentation page. Be sure to also download the errata document for the PV reference manual.

Best regards,


Thank you once again for the quick and useful reply Paul!

I just checked the Appendix B of the California Energy Commission "Guidelines for California's Solar Electric Incentive Programs (Senate Bill 1)." and this the only part which deals with BIPV mounting specifications:

1.Mounting Specifications for NOCT Testing for Building Integrated Photovoltaic (BIPV) Modules Intended for Roof-Integrated Installations
The test modules shall be in the middle of an array that is at least four feet high
and four feet wide. The array shall be surrounded on all sides with a minimum of three feet of
the building system for which the BIPV system is designed to be compatible, and the entire
assembly shall be installed and sealed as specified by the manufacturer for a normal

What I would like to know if whether I can identify the default mounting configuration of the picked module from the CEC Modules Library?
I understand that I can alter its mounting configuration through NOCT cell temperature model.
But is it possible to somehow predict what is the default mounting configuration of the module picked from the CEC Modules Library?

In previous topic:
you helped me identify the default mounting configuration of the picked module from Sandia Modules Library.
We assumed these based on their 'dT' values:
dt is 2 or 3: Open rack
dt is 1: Close roof mount
dt is 0: Insulated back

I would like to do the same thing, but this time for modules from CEC Modules Library.

CEC Modules Library does not contain the 'dT' column, but it does contain the "BIPV" column with values "Y(es)" and "N(o)". At least the "BIPV" column is visible once the CEC Modules Library.csv file is opened.
So based on these, maybe we can assume that if the chosen module has "BIPV" = "Y", then its mounting configuration can be insulated back (or BIPV without airflow behind it).
But if "BIPV" = "N", then I assume that it that case module's default mounting configuration can be either Open rack or Close (flush) roof mount.
But which one of these two? Isn't there a way to assume which one, based on some value from the CEC Module Library?

Thank you for the reply in advance, and sorry for disturbance.


The Sandia and CEC models handle the effects of mounting very differently. The CEC requires that BIPV modules be tested as they are intended to be installed, which results in much higher NOCT values for those modules than for non-BIPV modules. Therefore, no NOCT adjustment is performed when running the model, since the CEC data can be reasonably expected to represent the module's performance in actual conditions of use.

The CEC library data for non-BIPV modules is based on an open mounting system with unobstructed airflow (see IEC 61215 section 10.5, referenced in the CEC Guidelines document you are familiar with). The model as implemented in SAM has provisions for adjusting both the wind speed and the NOCT, if the module is not installed in an open rack.

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