In Texas, an ESI ID (Electric Service Identifier) is a unique number assigned to each point of electric service delivery to a residence or business. This number is used to identify a specific location in the deregulated electricity market of Texas. It's similar in concept to an account number, but it's linked to the physical location rather than a particular customer.
If ever needed, the number is typically found on your electricity bill or inside of your NextVolt Energy MyAccount.