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Meter for photovoltaic energy: how does a bidirectional meter and other types work?

If you have a photovoltaic self-consumption installation with surpluses, or are thinking of doing it, you have surely heard of the bidirectional meter. It is an essential device since it will allow the marketer to pay you for your surpluses and in this way, reduce the price of your electricity bill.

Meter for photovoltaic energy: how does a bidirectional meter and other types work?

One of the essential elements of modern photovoltaic installation equipment is an energy meter. Investors who decide to install PV can choose from many types of metering devices.

  • Which of them are the most popular and why is the bi-directional energy meter the most popular choice?
  • How to correctly read the values ​​displayed on the device?

We answer these and many other equally important questions in our post. We invite you to read!

The principle of operation of the electricity meter

A photovoltaic energy meter is a device that indicates the amount of electricity consumed by the recipient, allowing him to settle accounts with the seller. Today, the choice of meters is quite large and investors can buy both older and newer inductive devices, based on smart technology solutions.

In addition, there are also  bi-directional meters  , which are primarily intended for prosumers. This group includes people who produce electricity from renewable energy sources; in practice, electricity is most often produced by photovoltaic panels. What is worth knowing about the popular two-way electricity meter? 

What is a bidirectional electric meter?

The bidirectional meter is the device that is responsible for counting the energy that flows in both directions: from the electrical network to the user (like any other digital meter), as well as the energy that the user pours into the network.

This  photovoltaic component  is essential in self consumption facilities  with surpluses . When you do not consume the energy produced by the  solar panels  and inject it into the electricity grid, the marketer will compensate you for the energy surpluses and will mean a significant saving in the price of your bill.

Owners of photovoltaic installations most often decide to install a bidirectional energy meter.

Meter for photovoltaic energy

How does this type of device work?

It not only counts the amount of electricity drawn from the grid, but it also shows the amount of electricity produced by solar panels and the surplus entering the grid at the same time.

It is worth noting that in most installations, the amount of electricity produced by photovoltaic cells is not completely consumed. In this case, it is necessary to send it to the power grid. This type of investment in photovoltaic energy is known as  a grid-connected system  . It is thanks to the use of bi-directional active energy metering that prosumers can effectively settle bills with the energy company without losing anything.

Therefore, it can be safely stated that a bidirectional meter is used when the energy receiver is at the same time its producer. When do you ride most often? When it comes to comprehensive equipment for micro and small photovoltaic installations.

It should be added that according to the law, a micro installation is a photovoltaic installation whose total power does not exceed 50 kWp.

Replacing the meter or counter with a bi-directional one

The installation of a suitable energy meter for photovoltaics is the basis for a proper  settlement with the energy company  . Therefore, it is convenient to know that   it is not the receiver (inverter) but the network operator who is responsible for replacing the measuring device with a bidirectional one  . In order to discuss failure to pay the costs of such replacement, the facility owner must submit a proper application with all necessary attachments. They will mainly refer to the presentation of documentation for your photovoltaic installation.

If the request is submitted correctly, the network operator is obliged to install a new meter  within 30 days from the date of receipt of the document  . There are no costs incurred by the inverter when installing a two-way meter if the user owns micro-installations up to 50 kWp.

App profitability

Meter for photovoltaic energy

It is worth knowing that the owners of a photovoltaic installation should use a bidirectional meter.

What would happen if the photovoltaic installation coexisted with a unidirectional meter? Then the surplus energy sent to the grid would be recorded as imported energy. Therefore, it is easy to guess that this would result in very high electricity bills.

Therefore, it is worth avoiding such a situation and making sure to submit an application for the installation of a device for bi-directional measurement of active energy. Without it, PV is classified as a low-profit investment.

What makes bi-directional electricity meters so different from other energy metering devices? Your action deserves attention. These meters often monitor the quality and stability of the power supply to indicate any deviations from the norm.

They are also often used in various energy consumption management and control systems, helping to increase the energy efficiency of small businesses.

It is worth adding that some of the bi-directional meters available on the market are devices manufactured to   an industry standard  . Therefore, they will prove their worth in DIN rail mounting and prove to be a great solution used for installation in standard switchboards. Their distinctive feature is that they combine high strength, small size and a wide measuring range in one. In addition, they have many important communication interfaces built in and do not require additional calibration in countries throughout the European Union. 

How to read a bidirectional counter?

An extremely important concept related to a photovoltaic installation and a bidirectional meter is also  the net metering, that is, the net metering  . What does it mean?

The term refers to the possibility of storing electricity in a collective power grid. Users of modern photovoltaic installations know very well that not always all the electricity produced by solar cells is consumed continuously.

Net metering allows the sale of surplus electricity and its safe storage. Users using this option can store electricity on the grid and collect it when needed.

How to read a bi-directional meter?

How to read a bi-directional meter?

It is worth remembering that the device displays several parameters:

  • current state of energy consumption,
  • date,
  • hour
  • and the current electricity tariff, that is, the OBIS Code (displayed as three digits separated by a period).

Additionally, bi-directional meters operate on a single or multi-zone rate. Users who are billed in the actual consumption system should remember to round the status to full kWh. 

Diagram of the operation of a bidirectional meter

The use of a bidirectional meter in a photovoltaic installation allows the occurrence of one of the   three possible scenarios of electricity consumption  .

  1. The first is when the installation   has  not produced enough electricity  to cover all consumption. The meter then records the amount of energy transferred to the receiver from the public grid, for which the receiver will have to pay.
  2. The second scenario assumes a situation in which, after the end of the accounting period, the  balance of energy produced and consumed will be 0  . So, the recipient does not pay extra for the energy, but only assumes the costs of operating the network, that is, he pays the so-called meter fee.
  3. In the third scenario  , the photovoltaic installation produces more electricity than the farm’s consumption  in a given accounting cycle. The excess energy is transferred to the public grid and the bidirectional meter’s task is to record the exact amount of kWh consumed by the operator. In such a situation, the recipient does not pay for the energy and in the future can recover 70 to 80% of the energy delivered. It is worth adding that it must be done within a year of its delivery. Failure to comply with this period causes the irrecoverable loss of the stocks stored.

Where is the one-way counter installed?

There are investments in which there is no obligation to install a bidirectional energy meter. Speech incl. on buildings without photovoltaic installation. In such objects, current and voltage measurement is only possible in one direction and refers only to power consumption from the network.

One-way meters can be found most often in classic domestic buildings. The task of these devices is to read data on electricity consumption, so that the energy company can issue a proper bill on its basis.

Other types of energy meters

Do you currently use only bi-directional meters? As for PV users, the answer will be yes. If we refer to recipients who live in facilities not equipped with photovoltaics, the answer will not be so clear. 

In homes or other facilities, both the one-way meters found in older inductive models and much newer electronic devices can be used. A characteristic feature of induction meters is that they have an aluminum disc, but at the same time they also have a built-in blocking of their reverse rotation. On the other hand, electronic meters measure the amount of energy consumed, regardless of the direction from which it flows. In the case of a photovoltaic installation, if we do not use all the electricity it produces, this settlement will be very unfavorable.

Other types of energy meters

Furthermore, the measuring devices can be  single-phase or three-phase  . It should be added that nowadays modern and intelligent meters are also used, which allow the energy seller to download their status remotely. In addition, higher-class devices are often equipped with functions such as notifying the power distributor about failures or automatic uploading of software updates. However, the main task of each meter is to measure the energy consumed by the consumer. 

Summary in one word 

The best measuring device for photovoltaic installations is a bidirectional meter. It is the only meter that allows the correct calculation of electricity consumption and the determination of the amount of energy put into the network for storage.

In most photovoltaic installations, all the electricity produced is not consumed continuously, therefore its storage is recommended.

If you want to use the many functions of this device, you must send a request to the network operator. The latter, in turn, within 30 days following the date of receipt of the notification, is obliged to replace the traditional meter with a bi-directional active energy measurement device.