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Self-generation (Net-Metering) Industrial buildings - Average voltage


Net-Metering is the energy netting of the produced energy of a photovoltaic plant with the consumed energy of a consumption supply.

 The production station can be installed either in the same or adjacent space as the consumption installation or in a space remote from the electrical installation as long as it is electrically connected to a dedicated interconnection line which will be part of the internal electrical installation.

The PV system can be installed on a building or on the ground.

During the operation of a PV system, the need for energy from the supply to which the PV system is connected is first covered by the PV, while if this energy is not sufficient to cover the demand, then you absorb energy from the grid. While in the event that the PV system produces more energy than the supply needs at the given moment, this is channeled into the grid in order to offset the energy you absorb from the grid when the PV is not producing.

It is also possible, in a PV Net metering system, to add accumulators where during the day in case of excess energy it is stored in the batteries in order to be used in the evening hours thus reducing the energy you absorb from the network.

The power of a PV plant cannot exceed 10kWp for domestic supplies and 100kWp for professional supplies.

The right to install a PV system within the framework of Net Metering are natural persons and legal entities of public or private law who have the legal use of the installation space (in the case of leasing, the written consent of the owner is required) and who have an active power supply.

A photovoltaic system can be connected exclusively to a single consumption supply, while a supply that has a PV self-production system does not enter into another energy offset. The calculation of the produced energy and its offsetting with the consumed energy is carried out by the provider in each settlement account, in case of surplus energy you transfer it to the next settlement account up to 3 years. In the event of excess energy during the final settlement after the three-year period has passed, it is channeled into the grid for free and a new 3-year cycle begins.

A Net-Metering system consists exclusively of the photovoltaic frames with those of the support bases, the power converter, the electrical material (i.e. cables, electrical protection panels and switchgear) as well as the metering device of the HEDNO which receives data on the production of the photovoltaic station, while in the case of Net metering with storage it is used to accumulate with the appropriate management unit The concept of self-generation is already applied in many countries, while in Greece it has been a state law since 2015.

In the latest law 5037/2023, all the procedures, conditions and margins for installing a PV system in the context of self-generation are defined, while the differences of Net metering and Net Billing.

Example of depreciation of a 100 kW professional installation:

2. Virtual Energy Netting (Virtual Net Meteing)

With virtual net metering, it is permissible to offset the energy injected into the grid by a PV production station with the absorbed energy from one or more supplies of the self-producer, without the restriction that the PV system be in the same place as the consumption facilities.

Legal entities of public or private law that pursue public benefit purposes, farmers by profession (for agricultural benefits) and energy communities have the right to join the virtual energy netting.

The consumption benefits to be offset and the supply of the PV station must meet the following conditions:

1. They must all be in the name of the self-producer (TIN).

2. Be represented by the same provider

3. They must all belong to the same network administrator.

4. Be in the same regional unit.

5. Not to engage in another netting.


Net-Billing is the new energy netting method for energy-intensive businesses seeking installations over 100kW based on Law 5037/2023. The way the system works is similar to that of Net-Metering with the difference that the injected energy is not offset but compensated in one of the ways provided by the current legislation.

The equipment required to install a Net-Billing system is no different from that of Net-Metering. The only difference is in the way the investment is priced and amortized. Net Metering and Net Billing Differences

• In Net-metering, kilowatt-hours are offset, while in net-billing, a financial offset is made to the electricity bill.

• Energy netting in Net-metering concerns all the energy produced by photovoltaics, while in Net Billing only the percentage of the energy produced is self-consumed in real time.

• In net-metering, the generated energy that is not self-consumed in real time is injected into the network where it is 'stored' for a period of up to three years. After the three years, there is a liquidation and any excess energy for the consumer is not compensated. On the contrary, in net-billing all excess energy is injected into the network and compensated in one of the ways provided by the legislation.

• In Net-metering there is now a maximum power limit of 10 kWp for domestic services & 100 kWp for professional businesses, while in Net-Billing there is no limit, only that of the installation's supply.

• For businesses you do not allow virtual net-metering. On the contrary, virtual net-billing can be done by a single company or through a renewable energy community.

Ways of compensation for injected energy according to current legislation:

• €65.74/MWh (until August 2024) for energy injection into the Grid less than 1,500MWh per year

• Participate in a competitive bidding process or directly in electricity markets through FOSE or enter into bilateral agreements (PPAs) for the injection of energy into the Grid greater than 1,500MWh per year.


3.1 DEPRECIATION - RETURNS Example of amortization of Net billing system by selling the injected energy.



Virtual Net billing is the possibility of installing a PV station, in a different place from the location of the consumption supply. In Virtual Net billing you allow the virtual offset of energy from a PV station with more than one consumption supply of the self-producer.

All the energy produced by the photovoltaic plant is fed into the grid and offset in real time with the consumption at the user's premises.

Self-consumer installations normally receive energy from the grid

The incoming energy drawn from the grid by the self-consumer, the energy simultaneously produced by the photovoltaic station is subtracted.

The remaining cost of the energy drawn from the grid (after deducting the energy simultaneously produced by the photovoltaic station) will be offset against the amount corresponding to the energy sold (offsetting in €).

The installation location of the PV plant can be in any region, regardless of where the consumption facilities are located.


The rapid development of A.P.E. and especially of photovoltaic networks have now become saturated. In practice, the energy produced by photovoltaic plants is high enough that the transmission networks cannot handle it.

The solution to energy management is offered by Zero Feed-In. With the Zero Feed-In solution, the generated energy of the photovoltaic system is available exclusively for the consumption of the installation without being injected into the grid and affecting its limits.

The equipment governing a Zero Feed-In self-generation system is exactly the same as that of Net-Metering with the additional addition of an energy analyzer which blocks the flow of energy to the grid.


The self-consumer can install a generating station without injecting the produced energy into the Network, but for its own consumption, with an installed power up to 100% of the Agreed Power of the consumption supply. The zero feed-in scheme makes it possible to connect the generating station to a saturated network, as long as the saturation is due to exceeding the nominal power of the network elements or exceeding the desired voltage limits at network nodes.


Example of system depreciation with zero feed in


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