Regulations concerning the connection of inverters to the electricity grid are evolving. The NF EN 50549 standard is gradually replacing older directives, notably DIN VDE 0126-1-1. This transition, framed by the European network code RfG, aims to harmonise requirements and simplify procedures. The vfr2019 in France marks an important step in this update, impacting electricity generation installations, particularly those over 800W. It is therefore essential for professionals to fully understand these new rules to ensure the conformity of their equipment and avoid any inconvenience.

Key Points to Remember

• The NF EN 50549 standard becomes the new benchmark for inverter conformity in France from 2025, replacing DIN VDE 0126-1-1, following the European network code RfG.
• Electricity generation installations over 800W, for which the connection request is submitted after 1st January 2025, must comply with NF EN 50549.
• Decoupling protection, integrated into low-voltage inverters, is a crucial safety function to prevent risks during interventions on the public grid.
• Annex C of NF EN 50549 specifies the required grid operating parameters, with the possibility for each grid operator to define its own specificities.
• Derogatory provisions and temporary relaxations exist, particularly for installations with power less than 36 kVA, but it is crucial for installers to verify equipment conformity with manufacturers.

Evolution of conformity requirements for inverters

The regulatory landscape concerning inverters, these essential components of our photovoltaic installations, is undergoing significant change. The objective is to standardise electricity grid connection rules, which should, in the long term, simplify procedures and reduce equipment certification times. This evolution is part of the European network code Requirements for Generators (RfG), whose specificities are detailed in France by the technical decree of June 2020.

Transition from DIN VDE 0126-1-1 to NF EN 50549 standard

Until now, inverter conformity, particularly for the decoupling protection function integrated into low-voltage (LV) installations, was primarily attested by the DIN VDE 0126-1-1 standard. However, this standard is gradually being replaced. From 1st January 2025, the reference standard for connection requests will become NF EN 50549. This new standard, which is an integral part of the European network code, defines the technical requirements for the operation and protection of electrical installations connected to grids. Installations for which the connection request is made after this date and whose power exceeds 800 W will imperatively have to provide a certificate of conformity to NF EN50549-1 (for LV) or NF EN50549-2 (for HV A).

Impact of the European network code Requirements for Generators (RfG)

The European network code RfG aims to harmonise connection requirements across Europe. The NF EN 50549 standard is the text that transposes these European requirements at national level. It details the protection functions and operational capabilities that equipment must possess to be connected to the grid. This includes crucial aspects such as the inverter’s response to grid frequency and voltage variations, as well as its ability to disconnect in the event of a problem on the public grid. Compliance with this standard is therefore a mandatory step for placing new equipment on the market and installing it.

New deadlines for equipment certification

The entry into force of the NF EN 50549 standard on 1st January 2025 marks a turning point. It is important to note that the equipment conformity certificate can be provided at the latest during the commissioning of the installation, without blocking the completeness of the initial connection request. Derogatory provisions are planned for Annex C of the standard, which specifies the grid operating parameters. Initially, an attestation of equipment settings according to this annex will be tolerated if the certificate of conformity does not explicitly mention it. For installations with power less than 36 kVA, an exception is granted until 1st January 2026: the NF EN50549 conformity certificate will be accepted even if it is not established according to the test standard NF EN50549-10. Installers must therefore ensure the conformity of Hoymiles inverters with manufacturers to avoid any unpleasant surprises.

The NF EN 50549 standard: a key reference

The NF EN 50549 standard now represents the technical pillar for connecting electricity generation installations to the grid. It stems directly from the European network code Requirements for Generators (RfG) and specifies the requirements relating to equipment protection functions and operational capabilities.

Details on protection and operational functions

This standard details the essential safety mechanisms, notably the decoupling protection function. For low-voltage (LV) installations, this device acts as a safety interface between the photovoltaic installation and the public grid. It is designed to quickly detect and react to grid anomalies, such as multiphase faults, loss of synchronisation, or interruption of the main supply. These functions are ensured by the precise measurement of frequencies and voltages, which must remain within intervals defined by the grid operator. Compliance with these intervals is fundamental to guarantee the safety and stability of the electricity grid.

Application to electricity generation installations

From 1st January 2025, any new connection request for installations whose power exceeds 800 W must be accompanied by a certificate of conformity to NF EN 50549-1 (for LV) or NF EN 50549-2 (for HV A). This certificate must confirm the equipment’s conformity to the standard itself, as well as to associated test standards, such as NF EN 50549-10, and to Annex C.

Specific requirements for low voltage (LV) and high voltage (HV A)

The standard clearly distinguishes requirements according to voltage level. In low voltage, the focus is on decoupling protection integrated into inverters, which must meet strict criteria for grid fault detection. For high voltage (HV A), requirements concern more complex aspects of power management and grid stability. It is important to note that for installations with power exceeding 36 kVA, conformity to NF EN 50549-10 becomes mandatory from 1st January 2025, as stipulated in the regulatory updates for electricity generation installations.

The adoption of the NF EN 50549 standard aims to harmonise connection rules across Europe, thereby simplifying procedures for manufacturers and installers while strengthening the safety and reliability of electricity grids.

Scope and power thresholds concerned

The new vfr2019 regulation, which aligns with the European network code ‘Requirements for Generators’ (RfG), redefines the connection conditions for electricity generation installations. It is important to note that these new requirements apply to installations for which the connection request is made after 1st January 2025, and this, as soon as their power exceeds 800 W. This means that even small residential solar installations are affected by these changes.

Installations over 800 W subject to new requirements

From 1st January 2025, any inverter intended to be connected to the public grid and whose installation power exceeds 800 W must comply with the NF EN 50549 standard. This standard, which gradually replaces the previous reference DIN VDE 0126-1-1, specifies the protection functions and operational capabilities required to ensure a safe and stable connection to the grid. The certificate of conformity to this standard is now an essential document.

Connection request deadlines impacted by vfr2019

The date of your connection request is a key element in determining which regulation applies. If your request is submitted before 1st January 2025, the old rules based on DIN VDE 0126-1-1 remain valid. However, for any request made from this date, conformity to NF EN 50549 is mandatory. It is therefore advisable to anticipate your procedures to avoid any delays related to equipment conformity. Complete connection requests submitted before 22nd September 2025, for installations up to 500 kWp, still benefit from certain provisions of the October 2021 tariff decree, but the inverter standard remains an essential point see the decree criteria.

Tolerances for certificates not compliant with Annex C

Annex C of the NF EN 50549 standard details specific operating parameters that inverters must comply with to interact correctly with the grid. Initially, for installations with power less than 36 kVA, a tolerance is granted: if the certificate of conformity does not explicitly mention Annex C, an attestation of equipment settings according to this annex will be accepted by Enedis. This provision is valid until 1st January 2026. However, it is planned that eventually, installations will have to be verified by a control body, and discussions are underway to define the conditions applicable to low-voltage installations exceeding 36 kVA.

Here is a summary table of key thresholds and dates:

Installation Type	Power	Connection Request Deadline	Inverter Conformity Standard	Annex C Tolerance
New installation	> 800 W	Before 01/01/2025	DIN VDE 0126-1-1	Not applicable
New installation	> 800 W	After 01/01/2025	NF EN 50549	Yes, until 01/01/2026 for < 36 kVA
Existing installation	All powers	N/A	N/A	N/A

It is therefore essential for installers to ensure with manufacturers that the inverters they offer comply with the requirements of the NF EN 50549 standard, including the specificities of Annex C, to avoid any unpleasant surprises during commissioning.

Essential functionalities: decoupling protection

Decoupling protection, often called an automatic disconnection device, plays a leading role in the safety of electrical installations connected to the grid. Its main objective is to interrupt energy production when the public grid experiences an outage. This function is absolutely vital to prevent any risk of electrocution for technicians working on power lines. For systems connected to low voltage (LV), this protection is generally integrated directly into the inverter. In contrast, for high voltage (HV A) installations, equipment distinct from the inverter is required to provide this external safety function.

Historically, the European inverter market was largely influenced by German standards, notably DIN VDE 0126-1-1. Although this standard has been replaced, its reference has persisted in some technical documentation, including the VFR2014 and VFR2019 versions used by Enedis. However, from 1st January 2025, the reference standard for the conformity of grid-connected equipment becomes NF EN 50549. This evolution is part of the European network code Requirements for Generators (RfG), aiming to harmonise connection requirements.

Role of the automatic disconnection device

The automatic disconnection device acts as an essential safety interface between your generation system and the public grid. It is designed to quickly detect grid anomalies, such as multiphase faults or loss of voltage. By measuring key parameters like frequency and voltage, it determines if these values fall outside the acceptable ranges defined by the grid operator. If so, the device triggers an immediate disconnection to protect both the grid and people.

Integration into low-voltage (LV) inverters

In the case of low-voltage photovoltaic installations, decoupling protection is a functionality integrated directly into the inverter. This simplifies installation and reduces the number of necessary components. The inverter must then meet the requirements of the NF EN 50549-1 standard, which specifies the characteristics of this protection for LV systems. It is important to ensure that the chosen inverter has this certification to guarantee the conformity of the installation. You can verify equipment conformity with manufacturers to ensure they comply with the new standards.

Specific requirements for high-voltage (HV A) installations

For installations connected to high voltage (HV A), decoupling protection cannot be provided solely by the inverter. A dedicated external equipment is mandatory. This additional device must meet the specifications of the NF EN 50549-2 standard. Grid operators can also define specific parameters in Annex C of this standard, which must be taken into account for parallel grid operation. Eventually, these installations may require verification by an independent control body.

The transition to the NF EN 50549 standard marks an important step for the safety and interoperability of electricity generation installations. It is essential for installers and manufacturers to fully understand these new requirements to offer compliant equipment and guarantee grid safety.

Annex C: grid operating parameters

Annex C of the NF EN 50549 standard details the specific parameters that electricity generation equipment must comply with to operate in parallel with the electricity grid. These parameters are essential to guarantee grid stability and safety. They cover various aspects, such as acceptable voltage and frequency ranges, as well as how the equipment must react to grid variations, such as a frequency drop. Each grid operator can define its own values for these parameters, to adapt them to the specific characteristics of its operating grid.

Parameters required for parallel grid operation

Annex C establishes a list of settings and behaviours that inverters and other generation devices must adopt. These requirements aim to ensure harmonious and secure integration of decentralised installations into the public grid.

The main parameters concern:

• Voltage ranges: The voltage limits within which the equipment can operate without disconnecting.
• Frequency ranges: The grid frequency limits for normal operation.
• Active power response: How injected power must be adjusted according to grid frequency variations.
• Overvoltage and undervoltage protection: The thresholds and response times for disconnecting in case of abnormal voltages.
• Overfrequency and underfrequency protection: The thresholds and response times for disconnecting in case of abnormal frequencies.

Specificities defined by grid operators

Although the NF EN 50549 standard provides a general framework, it allows distribution network operators (DNOs) leeway to adjust certain parameters. These specificities make it possible to take into account the local particularities of each network. For example, a DNO may require narrower voltage ranges or faster response times for certain protections, depending on the density of generation installations or the network configuration. It is therefore essential to consult the specific requirements of each DNO, such as Enedis.

Future developments with verification by a control body

Ultimately, the conformity of installations to the requirements of Annex C, and more broadly to the NF EN 50549 standard, will be subject to verification by an independent control body. This additional step aims to strengthen the reliability of connections. Discussions are underway to precisely define the application modalities of this verification, particularly for low-voltage installations whose power exceeds 36 kVA. This evolution is part of a global approach to improving the management and safety of electricity grids in the face of increasing decentralised renewable energies.

It is important to note that if the certificate of conformity does not explicitly mention Annex C, an attestation of equipment settings according to this annex will be temporarily tolerated by some grid operators. However, this tolerance has time limits.

Derogatory provisions and temporary relaxations

To facilitate the transition to the new standards, temporary measures have been put in place. These provisions aim to lighten the burden for certain types of installations and to allow market players the necessary time to adapt.

Exceptions for installations with power less than 36 kVA

Installations with power less than 36 kVA benefit from special treatment. For these systems, the NF EN 50549 conformity certificate will be accepted even if it has not been established according to the specific test standard NF EN 50549-10. This tolerance is valid until 1st January 2026, the deadline for the complete connection request. This allows owners of these installations not to be immediately impacted by the strictest testing requirements.

Extension of certificate validity until 2026

In addition to the exception mentioned above, another measure concerns the validity of certificates. For installations with power less than 36 kVA, existing certificates, even if they do not comply with Annex C of the standard, will be accepted. A simple attestation of equipment settings according to this annex will suffice. This provision is also effective until the beginning of 2026, thus offering a grace period for full conformity.

Adaptations for installations with power exceeding 36 kVA

Although larger power installations are generally subject to more rigorous requirements, adaptations are also planned. Discussions are underway to define the conditions for applying the new standards to low-voltage (LV) installations whose power exceeds 36 kVA. The objective is to find a balance between grid safety and technical feasibility for these larger systems. Installers are advised to stay informed of regulatory developments concerning these installations.

It is important to note that these relaxations are temporary. Professionals must anticipate the full application of the standards to avoid any problems during future connection requests or commissioning.

Responsibilities of installers and manufacturers

With the entry into force of vfr2019, the roles and duties of installers and inverter manufacturers are redefined. It is now imperative to ensure that each installed equipment meets the new conformity standards, notably NF EN 50549. The responsibility for placing compliant equipment on the market primarily lies with manufacturers. They must provide clear and complete technical documentation attesting to the conformity of their products with current regulatory requirements.

Verification of equipment conformity with manufacturers

For installers, the first step is to demand valid conformity certificates from manufacturers for the inverters they offer. It is no longer enough to rely on a simple declaration; official documents must be presented proving that the inverter complies with the specifications of NF EN 50549, including relevant annexes such as Annex C for grid operating parameters. Transparent communication between manufacturer and installer is therefore paramount to avoid any unpleasant surprises during inspections or connection requests.

Importance of inverter technical documentation

The technical documentation provided by the manufacturer is a key element. It must precisely detail the inverter’s characteristics, its protection functions, and above all, the grid operating parameters it is capable of managing. This documentation serves as a reference for the installer and will be examined by grid operators and, potentially, by control bodies. The absence or insufficiency of this documentation can lead to the rejection of a connection request or significant delays in the commissioning of the installation.

Anticipation of normative evolutions

The regulatory landscape for renewable energies is constantly evolving. Manufacturers, in particular, must demonstrate active normative watch to anticipate future requirements. This involves investing in research and development to design inverters that not only meet current standards but are also prepared for future updates. Installers, for their part, must stay informed of changes and ensure that the products they choose come from manufacturers renowned for their commitment to conformity and innovation.

Compliance with international and European standards

For your inverters to circulate freely on the market, they must comply with a certain number of rules, both at European and international levels. It’s a bit like having a technical passport for trade. These requirements are not there to annoy people, but to ensure that everything connected to the grid is safe, reliable, and will not create strange interferences. We are talking here about electrical safety, compatibility with the grid, and electromagnetic compatibility. Without this, no sale is possible in the European Union, for example.

CE certification and associated directives (LVD, EMC)

The first step, and it’s mandatory to sell anything in the EU, is CE certification. This means your equipment complies with several European directives. The two most important for inverters are the Low Voltage Directive (LVD) and the Electromagnetic Compatibility Directive (EMC).

• Low Voltage Directive (LVD): It ensures that your inverter operates safely, especially if it uses voltages between 50V and 1000V AC, or 75V and 1500V DC. For photovoltaic inverters, the reference standard is EN 62109, which is divided into two parts: Part 1 for general safety and Part 2 for more specific applications.
• Electromagnetic Compatibility Directive (EMC): This concerns two aspects: firstly, the inverter’s ability not to emit too many electromagnetic disturbances that could interfere with other devices, and secondly, its own resistance to external interferences. Commonly used standards here are in the EN 61000 series, such as EN 61000-6-1 (immunity) and EN 61000-6-3 (emissions), as well as EN 55032 for multimedia equipment.

Specific standards for the safety of photovoltaic inverters (EN 62109)

As mentioned, the EN 62109 standard is truly the reference for the safety of solar inverters. It details everything necessary to prevent electric shocks, fires, and other potential dangers related to the use of these devices. It is a rather technical standard, but it is essential to prove that your product does not pose a risk to users or property. It applies to large systems as well as small installations. We can say that it is the absolute foundation for safety.

Electromagnetic compatibility requirements

Beyond basic safety, one must also consider the electromagnetic environment. An inverter, by its operation, can generate waves. The EMC standard aims to limit these emissions so as not to disturb the neighbourhood (radio, television, other electronic devices). Conversely, it guarantees that the inverter itself will not be easily disturbed by external electromagnetic fields. It’s a bit like making sure your inverter doesn’t shout too loudly and isn’t too sensitive to the noise of others.

Compliance with international and European standards is not a mere administrative formality. It represents a commitment to user safety, electricity grid stability, and the overall performance of installations. These standards, such as the EN 62109 series for safety and EMC standards for compatibility, are the foundation upon which trust in photovoltaic inverter technologies rests.

It is important to note that each European country may have additional requirements or specific adaptations. For example, France has its own regulation, vfr2019, which is based on these European standards but may add specific details. Germany, with the VDE-AR-N 4105 standard, also has its particularities. Staying informed of these national specificities is therefore essential for successful commercialisation. Grid operators, such as Enedis in France, provide technical guides that specify these points, and it is essential to consult them for a compliant installation.

In summary, for an inverter to be accepted on the market, it must successfully pass safety and electromagnetic compatibility tests, often based on European standards such as EN 62109. This is a process that requires a good knowledge of the requirements and is fundamental for the reliability of photovoltaic systems. Manufacturers must therefore ensure that their products meet these criteria even before thinking about placing them on the market, which often includes specific certifications such as CE marking, which is a basic requirement for access to the European market.

Country-specific regulatory adaptations

Each country has its own way of managing the rules for grid-connected inverters. It’s a bit like having different rules for each game you play. So, you need to be well-informed before you start.

Specific requirements for the French market (vfr2019)

In France, regulations are evolving. Previously, the DIN VDE 0126-1-1 standard was used to verify that inverters were properly synchronised with the grid, especially for decoupling protection. But that is changing. Since 1st January 2025, the NF EN 50549 standard is the authoritative one. This is a requirement stemming from the European network code, ‘Requirements for Generators’ (RfG). All installations over 800 W that request a connection after this date must have a certificate compliant with this new standard. This concerns the conformity of the equipment itself, but also how it was tested, and specific points mentioned in Annex C of the standard. The attestation can be provided later, upon commissioning, but it is important to remember to request it.

Applicable standards in Germany (VDE-AR-N 4105)

Germany has its own standard, VDE-AR-N 4105. It is quite similar in spirit to the European standard, as it also aims to guarantee the stability of the electricity grid. It defines the parameters that the inverter must comply with to be able to connect to the German grid. It is necessary to ensure that the equipment is certified according to this standard to avoid any problems during installation. This is an important step for installers working in the German market.

Certifications required in other European countries

Europe is a bit of a patchwork of rules. For example, in Italy, the CEI 0-21 standard applies to low-voltage installations. In the Netherlands, the EN 50438-NL standard is found. In Belgium, it’s C10-11. Each country has its specificities, even if the general objective is the same: to ensure a safe and reliable connection to the grid. It is therefore essential to check local requirements before proposing a solution. Sometimes, a European certification is sufficient, but often, country-specific validation is required. For example, the United Kingdom now has its own UKCA certification, distinct from CE marking.

Here is an overview of the standards in a few countries:

Country	Main Standard
France	NF EN 50549-1
Germany	VDE-AR-N 4105
Italy	CEI 0-21
Netherlands	EN 50438-NL
United Kingdom	G99 / UKCA

It is important to note that these standards evolve. It is necessary to stay informed of the latest updates to guarantee the conformity of installations. Understanding these different regulations is a key step for any professional wishing to operate in several European markets. For more detailed information on connection requirements, consulting the technical documents of local grid operators is good practice such as those from Enedis.

The diversity of national standards, although rooted in common European objectives, requires constant vigilance from manufacturers and installers. A good knowledge of these specificities allows anticipating constraints and ensuring a smooth market launch of equipment.

Certification process and accredited bodies

For an inverter to be marketed and connected to the grid, it must go through a rigorous certification process. This process ensures that the equipment complies with current technical and safety standards. It generally involves several steps, from submitting an application to issuing a final certificate, including thorough testing.

CE marking is an essential preliminary step, attesting to conformity with relevant European directives, such as the Low Voltage Directive (LVD) and the Electromagnetic Compatibility Directive (EMC). However, for grid connection, specific certifications, often defined by national or European grid operators, are required.

Testing and certification bodies play a central role in this system. They are responsible for evaluating the conformity of inverters according to applicable standards, such as NF EN 50549. These bodies must be accredited to guarantee the reliability and impartiality of their evaluations.

Here are the key steps in the certification process:

• Submission of the technical file: The manufacturer must provide complete documentation including technical specifications, diagrams, preliminary test reports, and a description of the protection functions.
• Laboratory tests: Samples of the inverter are subjected to rigorous tests in accredited laboratories. These tests verify compliance with grid operating parameters (voltage, frequency, decoupling protection, etc.) defined by the standards.
• Factory audit (if applicable): For certain certifications, an audit of the production site may be necessary to verify the consistency of quality and manufacturing processes.
• Issuance of the certificate: Once all requirements are met, the certification body issues the certificate of conformity, authorising the marketing and connection of the inverter.

It is important to note that requirements may vary from country to country, even within the European Union. For example, Germany uses the VDE-AR-N 4105 standard, while France relies on NF EN 50549 within the framework of vfr2019. Manufacturers must therefore ensure that their products are certified for each target market.

The complexity and duration of the certification process require anticipated planning. Manufacturers must plan certification cycles that integrate into their product development schedule to avoid any delays in market launch.

To ensure your solar project is in good hands, it is essential to know the rules and the groups that validate installations. We explain how it works and who the recognised experts are. Want to know more about the steps to obtain certification? Visit our website to discover all the details and find the trusted organisations.

Conclusion: Adapting to new inverter requirements

The entry into force of the NF EN 50549 standard from 1st January 2025 marks an important step for inverter conformity in France. This evolution, aligned with the European network code RfG, aims to harmonise connection requirements and simplify procedures for electricity generation installations. Installers must now ensure that the equipment they offer meets these new standards, particularly NF EN 50549-1 for low voltage. Although transitional periods exist for certain requirements, such as Annex C, it is preferable to anticipate these changes to guarantee conformity and the smooth running of connection projects. This adaptation is necessary to ensure the safety and stability of the national electricity grid.

Frequently Asked Questions

What is the NF EN 50549 standard and why is it important?

The NF EN 50549 standard is a very important new rule for electricity-generating devices, such as inverters. It replaces older rules and ensures that these devices work well with the electricity grid, especially in case of problems. It’s like a driving licence for inverters that want to connect to the grid.

What types of installations are affected by these new rules?

If your installation produces more than 800 Watts, it is affected. This includes most solar installations for homes. If you apply to be connected to the grid after 1st January 2025, you will need to show that your inverter complies with the NF EN 50549 standard.

What is ‘decoupling protection’ and what is its role?

Decoupling protection is an essential safety function. Imagine the electricity grid suddenly shuts down. This protection automatically disconnects your installation to prevent current from flowing back into the grid while technicians are working on it. This prevents them from being electrocuted. It is often integrated into inverters for small installations.

What is Annex C of the NF EN 50549 standard?

Annex C provides precise instructions on how the inverter must react to changes in the grid, such as voltage or frequency variations. Each country may have slightly different rules in this annex to adapt to its own grid. It’s a bit like specific settings to ensure everything works perfectly together.

Are there any exceptions or deadlines for complying with these new rules?

Yes, there are a few exceptions. For installations under 36 kVA, there is a little more time to obtain full certification according to the NF EN 50549 standard, until 2026. This allows manufacturers and installers time to adapt.

What are the responsibilities of installers and manufacturers?

Manufacturers must ensure that their inverters comply with the NF EN 50549 standard. Installers, for their part, must check with manufacturers that the equipment they purchase is compliant. They must also keep all important documents and certificates. It’s a team effort to ensure safety.

Is CE certification still necessary?

Absolutely. CE certification remains a basic requirement for selling products in Europe. It shows that the inverter complies with electrical safety and electromagnetic compatibility rules. The NF EN 50549 standard complements this for aspects specific to grid connection.

How do I know if an inverter complies with the NF EN 50549 standard?

You should consult the technical documentation provided by the inverter manufacturer. It must clearly indicate compliance with the NF EN 50549 standard, and ideally, mention the tests carried out according to the NF EN 50549-10 standard. If in doubt, it is best to request an official certificate of conformity.