The MPAN or S Number is 21 digits long, consists only of numbers and uniquely identifies your supply point to your energy supplier. It is printed on your electricity bill - normally found on the front summary page or the detailed breakdown pages.
Here is an example of what the number should look like
The top half (sometimes referred to as the top line) of the MPAN tells us what kind of electricity you need. The bottom half (bottom line) identifies the location. The 13 digits from 9 to 21 (Distribution ID, Meter Point Number ID Number and Check) - is needed particularly when you switch supplier.