Large Temp File when Loading a Huge Dataset

Hi jasonyu623 - If changing the TEMP directory isn’t possible or practical, expanding the C drive may be necessary, especially if Power BI and other applications are heavily using it. You can consider moving or uninstalling unnecessary applications and data from the C drive or reallocating space if your system allows.

or 

If you’re only working with incremental data changes in your 340GB data source, consider using Dataflows or Incremental Refresh in Power BI. These options allow you to load only new or updated records, significantly reducing the volume of data processed at once, which helps manage temporary file size.

any of this process works as expected.