"The pssexcel module provides Python functions to export PSS ®E data or solution results to Excel spreadsheets."
"The excelpy module provides Python functions to interface with Excel. Use this module to create, populate
and format Excel workbooks from Python."
The pssexcel module exports results files in PSS/E format to Excel, whereas excelpy is a more "general purpose" module for exchanging data between PSS/E and Excel. I suspect that it is excelpy that you want. You could use openpyxl instead of excelpy, but I find that excelpy has all of the functionality that I want, and it is included with PSS/E so there's no need to do an additional python module installation (as with openpyxl).