DESCRIPTION

TECHNICAL FIELD [0001] The present invention relates to improvements to the systems and methods for producing and delivering electric energy. More in particular, the present invention relates to innovations in the systems and methods for producing energy in order to improve the efficiency thereof and to increase the security and efficiency in transferring data relating to the energy production, especially in order to pay the electric energy produced and delivered to a transport and/or distribution network, for example (although without limitation) generated from renewable sources.

BACKGROUND ART

[0002] In order to overcome the increasingly growing energy demand and to reduce the environmental impact of large electric power plants, especially fossil-fuel or nuclear-fuel thermal electric power plants, the construction of small, medium and large electric power plants is incentivized, especially of those using renewable sources, spread over the country area and owned both by physical persons and public entities. These plants produce energy that can be partially used to satisfy the demand of the power plant owner orproprietor and partially (or totally) sold on the energy market. [0003] One of the most common installations of this type is that using photovoltaic

(PV) panels for converting sun energy into electric energy. Also concentrating solar power (CSP) plants use the sun energy, indirectly converting it into electric energy by means of thermodynamic circuits. Further electric stations using renewable sources are wind plants, hydropower plants (impoundment facilities or diversion facilities), biomass power plants, biogas power plants, geothermal power plants, and others.

[0004] For autonomously producing electric energy, and selling the surplus electric energy produced in excess with respect to that required by the power plant owner or proprietor, it is also possible to use traditional energy sources, for example and especially natural gas, in cogeneration plants, where small-sized gas turbine generators, or other endothermic engines, are used for producing electric energy and thermal energy for the use in industrial cycles. These plants, even if generally using non-renewable sources, especially hydrocarbons, have high energy performance thanks to the use of waste heat from the thermodynamic cycle for producing the mechanical power used for operating the electric generators. In this case again, in case of an excess of produced electric energy, the surplus can be delivered to an electric energy transport and/or distribution network and sold to an operator of the electricity market.

[0005] In some countries, public financing and incentives are provided for incentivizing the investments in this kind of plants, in order to reduce the use of large thermal power stations, characterized by high environmental impact and high costs, and efficiently to exploit renewable sources through small-sized power plants.

[0006] One of the significant aspects for efficiently stimulating the diffusion of the plants for producing electric energy from renewable sources, or other plants, for example high energy efficiency cogeneration plants, is the economic yield for the power plant operator owner or proprietor, constituted by the public incentives and, in particular, by the payment of the produced energy made by the operator of the electricity market or any other energy market authority.

[0007] At the present time, each electric power plant for producing electric energy is equipped with a certified fiscal meter measuring the energy produced and delivered to the electric energy transport and/or distribution network. Based on the data from the fiscal meter, the energy market authority pays, at scheduled intervals, the due amount to the plant operator, owner or proprietor. The payment times are particularly long.

[0008] This is due to two factors. First of all, the amount to be paid is calculated on time intervals in the order of dozens of days or even months, usually sixty days. Moreover, the amount due for each time interval is paid after a further time interval, for example ninety days or one hundred and twenty days.

[0009] Practically, this means that the power plant owner, selling the produced energy delivering it to a transport and/or distribution network, receives the payment with a delay up to one hundred and fifty days from the date when the energy delivery began. This causes many inconveniences to the power plant operator, owner or proprietor, not only due to the delays in payment but also for the strictness of the accounting methods, the acceptance of the due amount and the payment thereof.

[0010] US 2010/0293045 discloses a system for producing electric energy from renewable sources, wherein the produced energy is delivered to the network. A large power plant is owned by a plurality of different owners (co-owners). The energy produced and delivered to the network is calculated and credited to each co-owner of the power plant based on his/her percentage ownership. The share of the energy produced and delivered to the network that is assigned to each co-owner is deducted from a meter that each co-owner has on his/her line, that records the electricity consumption of each co-owner. In this way, large centralized power plants, for example photovoltaic power plants, can be constructed, owned by more co-owners. All the energy produced by the plant is delivered to the network. Each co-owner can deduct, from his/her energy consumption, his/her share of energy produced by the centralized plant. Substantially, the energy produced by the centralized power plant is deducted from the consumption of each co-owner at the place where he/she lives, that can be far from the centralized power plant. This is simply done by deducting, from the energy amount recorded by the power meter, the energy delivered by the centralized power plant to the network. If the energy produced is more than the energy consumed, the money credit due to the plant co-owner is managed by the operator of the electricity market in a traditional way, and the money credit is thus paid with a long delay with respect to the date when the sold energy has been actually produced and delivered to the network.

[0011] It is therefore useful to provide a method that, without prejudice to the local law requirements in force in the single jurisdiction, allows greater efficiency in energy production and greater efficiency and security in managing the data on energy production.

SUMMARY OF THE INVENTION

[0012] According to a first aspect, a method is disclosed for increasing the efficiency in managing electric energy production through a power plant and for managing, more efficiently and securely, data relating to the production and useful for selling the produced energy by delivering it to a transport and/or distribution network. In a known manner, information is acquired on the energy delivered to the network by the plant, through a fiscal meter, with which the power plant is equipped. The information is transmitted to the operator of the electric system, in charge of paying said energy delivered to the network. Characteristically, and in order to overcome or alleviate the drawbacks and the limits of the current methods for managing the production of energy by private persons and the sale thereof to the operator, the method disclosed herein provides for a further step of transmitting to a credit providing entity, through a safe mutual authentication protocol, data containing information on the energy delivered to the network over time.

[0013] In the present context, the term“power plant” refers, except otherwise specified, to a plant adapted to generate electric energy, and therefore electrical power, using any energy source, renewable or not. A power plant may use, as primary energy source, a renewable source, for example (although without limitation) wind power (through PV conversion or thermal cycles), sun power, hydropower, wave power, tidal power, marine current power, biomass power, geothermal power, fuel cell energy; or it may use a non-renewable source, for example fossil fuels (gaseous, liquid or solid fuels).

[0014] In the present context, the term“network” or“distribution network”, or “transport and/or distribution network” generically refers, except otherwise specified, to a electrical network allowing to transport the energy produced by a power plant towards the outside of the plant that has produced it, in order to make it usable by users other than those belonging to the power plant in question.

[0015] Generally, data can be directly provided by the fiscal meter. Data from the fiscal meter may be directly transferred to the credit providing entity. Alternatively, data from the fiscal meter may be acquired by means of intermediate tools, hardware and/or software, which transmit them to the credit providing entity. It is also possible to acquire data through dedicated sensing devices, physically distinct from the fiscal meter, provided that data are consistent with those of the fiscal meter. To this end, data acquired through means distinct from the fiscal meter may be compared with those acquired through the fiscal meter and corrected, if so required. [0016] In this way, the operator of the energy market performs the financial performance (payment of the amount due for the energy produced and sold, including any incentives), in compliance with the laws in force in the jurisdiction where the agreement between the power plant owner and the operator of the energy market has been signed. However, the credit for the sold energy is granted by the credit providing entity to the power plant owner in shorter time. The credit providing entity may be, for example, a factoring company, a bank or any other entity adapted to grant a credit based on the measurement of the fiscal meter.

[0017] This results in greater efficiency and swiftness in payment.

[0018] In this context, unless otherwise specified, the term“credit” refers to an amount in currency, i.e. a money amount, that is a money credit (i.e. a money value) granted to the power plant operator, owner or proprietor, for instance, on the basis of an agreement signed with the electricity market operator. This money credit corresponds to the value of the energy delivered to the network (at the agreed price, that can vary, if necessary, depending on several parameters, as described below), including any incentives as provided by laws in force. It should be noted that, when the credit providing entity makes the money credit available for the power plant operator, owner orproprietor, this credit has already become due, that is the right to the corresponding amount is already granted by the agreement signed with the electricity market operator.

[0019] The use of a secure transmission protocol, for example an encrypted protocol, provided with a mutual authentication system of the communicating parties (transmission side and receiving side), technically ensures reliability, consistency and integrity of the received data.

[0020] In some advantageous embodiments, the transmitted data may be also configured so as to allow calculating not only the amount of energy delivered to the network, but also the amount of any incentives therefor. These incentives can vary from plant to plant, depending on several parameters. For example, the incentives granted to the energy producers may vary according to the type of primary sources, from which energy is obtained. Renewable sources, like wind, sun, water, geothermal sources etc., can have different incentives. Incentives can also vary depending on the size of the power plant, the jurisdiction within which the agreement has been signed, and other parameters. With the method and the system disclosed herein, (once known the base parameters for the calculation) it is possible to calculate automatically the incentives due for the energy produced and delivered to the network. In this way, the credit line of the power plant operator or owner (proprietor) can be credited, on a daily basis, not only with an amount corresponding to the energy actually produced and delivered to the network, but also with the amount corresponding to the incentives.

[0021] In practice, the credit providing entity receives, from the power plant, information on the sold energy that is consistent with the information given to the operator of the energy market. Based on this information, the credit providing entity can determine the amount that the operator of the energy market will grant to the power plant operator or owner, including any incentive for the production of renewable energy and/or any other type of incentive. Based on this information, the credit providing entity can credit the current account of the power plant owner with the amount corresponding to the amount that will be granted by the operator of the energy market. The current account of the power plant owner can be credited with this amount in a very short time and highly frequently. For example, the credit providing entity can calculate the credit on a daily basis, i.e. based on the energy produced and delivered to the network every day, and can convert it into a credit (i.e. money) that will be already available to the power plant owner the following day.

[0022] In this context, reference will be often done to a daily crediting of the amounts corresponding to the value of the energy delivered to the network. However, this shall not be understood as limiting in scope, and is a mere example, even if, in some cases, the preferred one. In fact, the system and method disclosed herein technically allow measuring the energy delivered to the network and communicating the corresponding data in real time. In theory, it is therefore possible to grant the money credit, i.e. the money amount corresponding to the energy delivered to the network, also in real time, i.e. on a time basis in the order of seconds or fractions thereof. The energy delivered to the network, and thus the value thereof, are known at any instant thanks to the measurement performed by means of the fiscal meter (or of any other independent instrument supplying data consistent with those from the fiscal meter). Such data can be transmitted to the credit providing entity at time intervals that can be defined at will, i.e. with the desired granularity; the credit providing entity can thus make the money amounts immediately available to the power plant operator, owner or proprietor. [0023] On the other hand, by continuously measuring data on the energy delivered to the network, it is possible to have aggregate data on longer time intervals, for example in order to decrease the costs for calculating and transmitting data. It is for example possible to supply data to the credit providing entity on a hourly basis (i.e. every hour), or on a daily or weekly basis. What is important is that data necessary for calculating the money credit granted to the power plant owner are available to the credit providing entity in shorter times than the payment processing times adopted by the electric energy market operator, and thus that the credit providing entity can grant the power plant operator, owner or proprietor the due money amounts in advance with respect to the actual payment made by the operator of the energy market.

[0024] As such, the time frequency for communicating data and/or making the corresponding credit available in advance by the credit providing entity can be very high, in practice by adopting, as mentioned, a real-time credit granting, or it can be lower, for example on a weekly or monthly basis, for example every three months or every ninety days. In this case again, the time interval is significantly shorter than that required by the electricity market operator for making the payment.

[0025] The frequency, i.e. the time granularity for calculating the money credit and for making the advance payment thereof available to the power plant operator, owner or proprietor, can be agreed between the power plant operator, and the credit providing entity. This frequency can also vary from a power plant operator to another. In some cases, the credit providing entity can ensure a higher frequency upon a payment made by the credit beneficiary, i.e. by the power plant operator, owner or proprietor, for example in the form of a higher or lower commission on the amounts credited or given by the credit providing entity to the power plant operator.

[0026] If necessary, the power plant owner can use the credit available on his/her account; in this case he/she will pay a commission to the credit providing entity. Just by way of example, this commission may depend on the amount and/or the period of time between the withdrawal of the credit from the account and the actual payment made by the energy market operator.

[0027] To this end, the credit providing entity can provide an online platform, which the power plant operator, owner or proprietor can access using personal credentials, or a specific app. Using a specific function, available under his/her profile in the online platform or under the corresponding app, the power plant owner has the option of accumulating the calculated amount corresponding to the produced energy, without transferring the corresponding money amount from the platform to an available current account. Alternatively, the owner can opt for having the money amount corresponding to the electric energy produced by the power plant immediately credited to his/her current account hold at a partner bank, for example. It should be highlighted that this is an option; similarly, the“where”,“when”, and“how” the service commissions and the interests, if any, are debited, shall be optional and shall be decided and agreed by the parties.

[0028] In the present context, the term credit providing entity refers to any entity adapted to receive certified information on the energy produced and sold by the single plant, and adapted to manage financial transactions for crediting the power plant owners with money amounts corresponding to the future amount that will be granted by the operator of the energy market.

[0029] In the present context, the terms“operator of the energy market”, or“operator of the electrical market”, or“operator of the electrical system” refer, in general, to the entity in charge of managing the financial transactions related to the energy sold and delivered to the network by the power plant operators, owners or proprietors. [0030] According to a further aspect, a system is disclosed, comprising at least an electric power plant, configured to produce electric energy and to deliver it to a public and/or private transport and/or distribution network. The electric power plant comprises at least one fiscal meter, adapted to give certified information on the energy, delivered to the network by the power plant, to a operator of the electric system in charge of paying the energy delivered to the network. Moreover, the plant has means for generating data, containing information on the energy delivered by the power plant to the network over time, and for transmitting them to a credit providing entity.

[0031] Further advantageous features and embodiments of the method and the system according to the present invention will be described hereunder and are set forth in the attached claims, which form an integral part of the present description. BRIEF DESCRIPTION OF THE DRAWING

[0032] The invention will be better understood by following the description below and the attached drawing, showing a non-limiting embodiment of the invention. More specifically, in the drawing:

Fig.l shows an exemplary block diagram of two power plants using renewable sources, interfacing with an electric energy transport and/or distribution network and with systems for measuring the delivered energy; and

Fig.2 shows a flow diagram.

DETAILED DESCRIPTION OF AN EMBODIMENT [0033] Fig. l shows a system comprising, by way of example, two power plants for producing electric energy from two different renewable sources. The two power plants are indicated with the reference numbers 1A and IB, respectively. Just by way of example, the plant 1 A is a photovoltaic plant, the plant IB is a wind plant.

[0034] In the illustrated exemplary embodiment, the provided plants use renewable sources. However, this shall not be considered as limiting. In fact, situations may be foreseen, wherein a private power plant owner or proprietor can sell, to an operator of the energy market, energy produced from traditional sources, i.e. non-renewable sources, for example produced using endothermic engines utilizing fossil or vegetable- based fuels. [0035] In the exemplary embodiment of Fig.1, the power plant 1 A comprises a field of photovoltaic panels 3, connected to one or more inverters 5. In the PV panels 3 the sun energy is directly converted into electric energy in the form of direct current.

[0036] The inverter 5, or a set of more inverters 5, converts the DC into AC at grid frequency. This current can be partially used for self-consumption, i.e. for powering a local network schematically indicated with the reference number 7. In the diagram of Fig. l, El indicates the energy delivered by the inverter 5 to the local network 7. In case of a domestic plant, the local network 7 can power, for example, domestic appliances, light systems or other electric devices usually used in a house. In other embodiments, the plant 1A may be an industrial plant for producing electric energy, which is partially used for self-consumption for powering industrial equipment. [0037] E2 indicates the energy delivered to a electric power distribution network 9, to which the output of the inverter 5 can be connected, for example through an electric cabin 10. A fiscal meter 11 may be provided for measuring the amount of energy E2 delivered to the transport and/or distribution network 9. The fiscal meter 11 is configured in compliance with the fiscal laws in force in the country where the plant 1 A is installed, and provides certified data on the energy production.

[0038] The fiscal meter 11 is adapted to provide an operator of the energy market, in charge of managing the purchase of the electric energy delivered to the network 9, with data on the energy produced and delivered to the network 9. In the diagram of Fig.1, the block 13 schematically represents the operator of the energy market or operator of the electric system. The reference number 15 indicates a communication channel, through which the information from the fiscal meter 11 is transmitted to the operator of the energy market 13. The communication channel 15 is illustrated as a physical entity distinct from the network 9, but it should be understood that the communication between the fiscal meter 11 and the operator of the energy market 13 may occur using, as physical channel, the same cables of the transport and/or distribution network 9.

[0039] The plant 1A further comprises a control system 19. In Fig.l the control system 19 schematically comprises, just by way of schematic example, a control panel (control dashboard) schematically indicated with 21, and a system 23, typically a computer with related processing software to be run on the computer, generating a flow of data containing information adapted to detect the plant 1 A and also containing information on the energy delivered by the inverter 5 to the network 9. This last information comes from the fiscal meter 11; thus, it perfectly corresponds, in a certified manner, to the data provided by the fiscal meter 11 to the operator of the energy market 13. As an alternative, as schematically shown in the diagram of Fig. l, data may arrive to the control system from a different sensor or group of sensors associated with the inverter (as indicated with a continuous line), provided that data from the sensor associated with the inverter are consistent with data from the fiscal meter. [0040] It should be understood that the control system 19 may be arranged close to the plant, as schematically shown in Fig.l, even if this is not necessary. It is also possible to transfer data on the produced energy, and/or other data on the plant operation, to a remote control system, through adequate communication channels and protocols.

[0041] The control system 19 transmits, through a transmission channel 25, the flow of data to a credit providing entity schematically indicated with the reference number 27. The transmission channel 25 may be any channel. Data generated by the software of the system 23 and the methods for transmitting these data to the credit providing entity 27 may be of any kind, provided that they are adequate to ensure authenticity and integrity of data received by the credit providing entity 27, and adapted to allow this entity to link certainly the received information to the plant, from which the information comes.

[0042] In some embodiments, the communication between the power plant 1A and the credit providing entity 27 may occur, for example, through WEB-API interfaces, allowing to exchange data through the Web in a structured, authenticated and encrypted way. [0043] In other embodiments, the communication of data from the control system 19 of the power plant 1A to the credit providing entity 27 may occur, for example, by sending text files, for instance XML files, for example on an external FTP server.

[0044] In yet further embodiments, the communication of data from the control system 19 of the plant 1 A to the credit providing entity 27 may occur, for example, via certified or uncertified email.

[0045] In practical embodiments, in the block schematically indicated with 23 a data analytics and workflow automation software can be provided and run, i.e. a software that substantially collects the energy production data, automatically processes them and sends them, for example in the form of digital/IT command or device, to a platform for money transactions and/or trading, or to a similar structure of the credit providing entity 27, in order to perform one or more transactions, as described below.

[0046] In order to automatize the process disclosed herein, integrity and security of data, supplied by the control system 19 to the credit providing entity 27 through the generic communication channel 25, are particularly important. To achieve this goal, data shall be exchanged through an authentication method (using for example user name and password, fingerprint recognition, retinal scanning and/or facial recognition, as well as any other digital/IT method of recognition), and through a protocol ensuring data security and integrity. In some embodiments, a TLS (Transport Layer Security) protocol may be used, or a security certificate. Advantageously and adequately, the transmission protocol is preferably a mutual authentication protocol, for example a mutual TLS protocol (briefly mTLS).

[0047] As schematically shown in Fig. l, data on channel 25 can be directly transferred to the credit providing entity 27, or to an intermediary 26 that can provide a data reception and authentication service, for example,. [0048] In all the above cases, data are exchanged though a safe and authenticated channel. At the present time, for example, the use of a WEB-API ensures higher security in data exchange, thanks to the intrinsic feature of this service.

[0049] Independently of the type of channel and the methods used for transmitting data, the credit providing entity 27 receives, from the plant 1A, certified data containing information on the amount of energy produced and delivered by the plant 1 A to the transport and/or distribution network 9. Data can be sent periodically, at an adequate frequency. Data can be advantageously aggregated, so that the credit providing entity 27 is able to know the amount of energy delivered from the plant 1 A to the transport and/or distribution network 9 every day, every hour, every minute, every second or fraction thereof. This allows granting the owner of the plant 1A a money credit on a daily basis.

[0050] According to particularly advantageous embodiments, the credit providing entity 27 is therefore able to determine, for each day, the money amount due to the owner of the power plant 1 A for the energy produced and delivered to the network, i.e. sold to the energy market. This credit can consist the energy price and any incentives in compliance with the local laws, and is made available to the owner of the plant 1 A the following day.

[0051] As already mentioned in the introductory part of this description, the calculation of the energy delivered to the network and the grant of the corresponding money credit to the power plant operator, owner orproprietor on a daily basis is just by way of non-limiting example, even if it is significantly useful. However, the method and system disclosed herein are technically adapted also to provide for a very higher frequency, i.e. a significantly shorter time interval, up to fraction of seconds. Conversely, lower frequencies than a daily frequency can be used, for example every two days, once a week, once a month, or even lower frequencies. [0052] If the energy price granted to the producer, i.e. to the owner of the plant 1A, in compliance with the local laws, varies according to the time slots when the energy has been delivered to the network 9, the credit providing entity 27 may calculate the credit taking into account also this variable. To this end, it is sufficient to collect the information on the energy delivered to the network by time slots. In other words, the control system 19 transmits information on the energy produced and sold by time slots, and the credit providing entity 27 receives the data and calculates the credit due to the operator or owner of the plant 1 A for each time slot.

[0053] Independently of the calculation method, and independently of whether the price of the energy sold by the operator or owner of the plant 1 A and delivered to the network 9 varies over the day, the credit providing entity 27 daily credits the single operator or owner of the plant 1A a credit corresponding to the sold energy. This is schematically indicated in block 29A, which may represent a current account for crediting the money amounts due to the operator or owner of the plant 1 A.

[0054] In Fig. l, to the block 27, schematizing the credit providing entity, more blocks 29 (29 A, 29B...29N) are connected, schematizing a plurality of current accounts corresponding to a plurality of power plant owners or to a corresponding plurality of production plants. Each owner may have, for example, a single current account, or a plurality of current accounts, each of which is associated with one or more production plants owned by the owner. [0055] The credit providing entity 27 manages the current account 29, that the owner of the plant 1 A can access to draw amounts in advance with respect to the date when the operator of the electric system 13 will actually pay for the energy sold by the owner of the plant 1 A. In practice, the credit corresponding to the sold energy (including any incentives) is immediately available to the owner of the plant 1A the day after that when the energy has been actually delivered to the network. The plant owner has therefore the opportunity to draw out of his/her current account (i.e. to collect from the credit providing entity 27) an amount equal to, or lower than, the sum of all credits due up to a certain date, for the energy sold up to that date, independently of the delay, of some months, of the operator of the electric system 13 in actually paying the amount due for the sold energy.

[0056] The power plant owner can decide whether to draw all, or part of, the credit, out of his/her current account, or to leave it in the current account.

[0057] The money amount that will be then paid by the operator of the electric system 13 can be credited, for example, directly to the credit providing entity 27, or to the power plant owner who will pay the credit providing entity 27 this amount increased by a given commission, that can be proportional to the part of credit that has been drawn out, and possibly variable depending on the interval between the withdrawal date and the deposit date. If the money amount is paid by the operator of the electric system 13 directly to the credit providing entity 27, this latter can withhold a commission, deducting it from the current account of the owner of the plant 1 A; this commission can be proportional to the part of credit drawn out by the owner and to the time between the credit withdrawal date and the date of deposit by the operator of the electric system.

[0058] Even if a daily credit of the amounts due to the power plant owner is particularly advantageous, it is also possible to grant the credit according to different modalities, for example every week, or with higher frequency, up to fraction of seconds, as mentioned above.

[0059] Essentially, the credit providing entity 27 grants the power plant owner the money value of the produced energy, and makes it available in the form of credit on a daily basis or on a different basis as agreed by the credit providing entity 27 and the power plant owner.

[0060] As clearly schematized in Fig. l, the credit providing entity 27 can manage a plurality of plants of one or more owners, through a plurality of distinct current accounts. In Fig. l is schematically shown, just by way of example, a second power plant IB for producing electric energy, interfacing with the same credit providing entity 27, which manages a current account 29B associated with the power plant IB. [0061] As the various electric energy production plants can use different energy sources, preferably renewable sources, in the diagram of Fig.1 the plant IB uses, just by way of example, a wind farm 4 instead of photovoltaic panels 3. The other components of the plant IB are substantially the same as those described with reference to the plant 1A, and are indicated with the same reference numbers. These components will not be described again.

[0062] Even if in the diagram of Fig.1 power plants 1A, IB are represented for the production of electric energy intended both for sale (delivery to the transport and/or distribution network 9) and self-consumption, it should be however understood that the managing system and method described above can be also used for plants producing electric energy only intended to be delivered to the network 9, i.e. only intended for sale.

[0063] In Fig.2 a functional block diagram is shown, summarizing the criteria for managing the electric energy production, for managing and granting credits by the credit providing entity 27, as well as for paying the money amount due by the operator of the electric system 13 for the sold energy. In the diagram of Fig.2, DT1 indicates the time interval, based on which the operator of the electric system 13 calculates the money amount to be paid for the sold energy. This time interval can be, for example, equal to sixty days. DT2 indicates the delay in paying the money amount due by the operator of the electric system 13 for the energy produced and sold in the interval DT 1.

The second time interval DT2 can be for example equal to ninety days or to one hundred and twenty days.

[0064] The advantages of the system disclosed herein are clearly apparent from the diagram of Fig.2. While the amount for the produced energy is calculated over intervals DT1 (for example sixty days) and paid after a further interval of DT2 days

(for example ninety days or one hundred and twenty days), the power plant owner shall not wait for a time DT1+DT2 (in the example, one hundred and fifty days or one hundred and eighty days) for having available the amount corresponding to the energy sold in the interval DT1; on the contrary, he/she can use the credit corresponding to the produced energy starting from the day after the production day. The power plant owner will decide whether or not to use this credit. The service fees can be freely agreed between the power plant owner and the credit providing entity 27. [0065] The method and system described herein can be used in a plant intended for both sale and self-consumption, i.e. a plant where part of the produced energy is used by the local users, ancillary to, or autonomous from, the power plant, such as equipment, machinery or apparatuses intended for domestic, commercial or industrial use. A self-consumption power plant can be typically a domestic plant with PV panels, where the electric power produced by the plant is partially used for powering the domestic users. However, the method and system disclosed herein can be also used in energy production plants where all the produced energy is intended to be delivered to the network. In both cases, what is taken into account for calculating and paying the money credit automatically granted to the power plant operator owner orproprietor by the credit providing entity is the energy delivered to the network, independently of whether part of the produced energy is used for self-consumption.