No, you will not be charged a fee to pay your bill online using your bank account if you sign in to Your Account.
However, if you pay your bill with a debit or credit card, or use the One Time Access tab (which does not require you to create a username and password), you will be charged a $1.35 convenience fee.
Note: The convenience fee is charged by an independent provider. PG&E does not receive any monies from convenience fees.