Hi Sara,
In general, we recommend converting weather files to the SAM CSV format to use with SAM. You can use the Solar Resource File Converter macro to convert from EPW to SAM CSV. (click Macros under the Simulate button to see a list of macros.
That said, you can add EPW files to the solar resource library on the Location and Resource page:
1. Click Add/remove weather file folders.
2. In the Solar Resource Folder Settings window, click Add, and select the folder that contains your EPW file(s).
3. Click OK.
SAM scans the folder and adds any valid weather files to the library. You may need to scroll to the bottom of the library list to see the newly added files. Before adding files to the library, SAM checks to see that they are valid, so if there are any problems with your EPW files, it will not add them to the library.
Best regards,
Paul.