Is there a way to export posted invoices into excel in NAV?
you can try by clicking send to excel in posted invoice list…
Click on the excel button avaliable in the menu bar of NAV.
If you want some thing specific then you will have to develop the same.
Depends on your version. You can copy and paste into Excel (all versions), click the Export to Excel button (5.0 and up) or write a custom report to do it (all versions)