How can I open an Excel file directly from the explorer in a new instance? The registry key disableMergeInstance has already been added but this doesn't have an effect on opening files from the windows explorer.
Create a shortcut for Excel.EXE file on the desktop (open its folder and use "RightClick - SendTo - to Desktop(create shortcut)", do not copy the shortcut from Main menu or QuickLaunch pane).
Drag the XLS/XLSX file over the shortcut - it will be opened in new, separate, Excel instance.
You can also open new Excel instance by Alt-Click on its icon or by starting it from command line by
excel /x command (or create shortcut with this command) - separate process will be started, then open the file.