Patent ID: 7840493

Claim:
A prepayment method of electric energy using: i) a contactless prepayment smart card having microcontroller with a memory storing a credit value for an amount of prepaid electrical energy to be purchased; ii) an electronic electricity energy meter comprising reader-writer means of contactless smart cards located within the electronic electricity energy meter and a memory; and iii) a network including a terminal of sale point having a pair of security modules, a server connected by a communication interface to a collect system that maintains information about a clients' bills and of information stored in a data base of a supplier; the method comprising the steps of: emitting a radiofrequency signal from the electronic electricity energy meter by means of a contactless prepayment control board; detecting a presence of a contactless prepayment smart card inside a detection field of the electronic electricity energy meter, wherein the electronic electricity energy meter is airtight and watertight; interchanging information between the electronic electricity energy meter and the contactless prepayment smart card by means of radiofrequency; authenticating the contactless prepayment smart card and the internal reader-writer means of contactless smart cards, in mutual form, by two or more digital signatures and a serial number of the electronic electricity energy meter; determining if the contactless prepayment smart card has a credit value greater than zero of the amount of prepaid electrical energy; discharging a part or the total amount of the credit value from the contactless prepayment smart card; receiving and storing the part or the total amount of the credit value of prepaid electrical energy from the contactless smart prepayment card into the memory of the electronic electricity energy meter; reading remaining credit in the electronic electricity energy meter; adding the total or partial credit discharged from the contactless prepayment smart card to the remaining credit in the electronic electricity energy meter to generate a new value of prepaid credit; and storing the new value of the prepaid credit in the memory of the electronic electricity energy meter; generating information about the state of the electronic electricity energy meter; and recording the information generated about the state of the electronic electricity energy meter into the contactless prepayment smart card, wherein the information comprises energy consumed by the user during the life of the electronic electricity energy meter, a credit of the meter, meter tampering, and a number of disconnections, interruptions, derivations, energy accumulated during use during the derivations and the inversions.