When your invoice is ready to be reviewed by PGE, click the "Submit to PGE" checkbox on invoice header tab. Doing so will verify all required documents have been uploaded, and mark the invoice as "Pending Review". That indicates to PGE that the invoice is ready to be reviewed for payment.
If there are any missing documents, the user will be warned that some are missing, but they are still able to submit the invoice anyway.
You are now asked to confirm your submission. Click Yes and the Submit to PGE is checked, the invoice status changes to "Pending Review", and the invoice can no longer be edited by the user. Once submitted, you have a brief period of time (currently 24 hours) where you are allowed to unsubmit the invoice as long as PG&E has not started the review process, which will allow you to make additional changes to an invoice.
If you wish to make edits, as long it has been less than 24 hours since invoice was last submitted, and the review process has not been started by PGE, you can un-Submit the invoice by un-checking the Submit to PGE checkbox, make any desired changes, then click Submit to PGE again.