Non-metered wireless system and method to render usage based invoices for storage tank consumables

A method, system and computer-readable medium for managing usage of storage tank consumables in a storage tank are provided. This is achieved by receiving and storing by a central server comprising a processor and a storage device, measurements of storage tank consumables from a remote system associated with a storage tank; periodically calculating by the processor usage-based data for generating invoices for storage tank consumables based on sensor measurements representative of an estimated usage of the storage tank consumables; receiving and storing by the central server a fill value representing an actual usage reported to the central server when the storage tank is filled; and reconciling the estimated usage with the actual usage by the processor by summing all estimated usages since a last fill of the storage tank, calculating a difference between the sum of the estimated usages and the fill value, and issuing a debit or credit based on the difference for reconciliation.