Hello,
There appears to something about the formatting of the revised TMY3 files (with "TYA" in the file name) that causes SAM to be unable to read them. (My initial investigation suggests that the problem might be caused by the number of columns in those files being different than in the original TMY3 files, and that the revised files appear to use Windows line endings instead of Unix line endings.)
SAM can read the original TMY3 files (with "TY" in the file name). Also, the complete TMY3 dataset is included with SAM as part of the solar resource library, so you don't really need to download TMY3 files from the NSRDB -- you can just choose the file from the list on the Location and Resource page.
If you want to download TMY3 files from the NSRDB site to use with SAM anyway, use the link under "Previous TMY3 Files (2008/08/20)" to download files from the original TMY3 dataset. I am working with the NSRDB team to resolve this issue.
The Notice dated January 19, 2015 on the
NSRDB 1991-2005 Update page
explains that the difference between the revised and original TMY3 dataset is mostly for data that SAM does not use (visibility, ceiling height, etc.) The only exception is any revisions to albedo values, which may have a small effect on photovoltaic simulations in SAM.
Best regards,
Paul.
