New law in Germany from February 1, 2025: 33 questions and answers about the ZEREZ requirement for photovoltaic systems

A far-reaching legal change affecting operators of photovoltaic systems will come into effect on February 1, 2025: the so-called ZEREZ obligation. This step is a significant milestone for the standardization and digitalization of the grid connection process in Germany. Below you will find everything you need to know about the ZEREZ obligation, how it works, and what it means for private and commercial system operators.

What is ZEREZ?

ZEREZ stands for "Central Register for Unit and Component Certificates". This central database system was created to efficiently and transparently record certificates for the components of power generation plants, such as photovoltaic systems and battery storage. ZEREZ serves as a digital register in which all relevant unit certificates, which play a central role in the security and reliability of the electricity grid, must be stored.

Centralized data collection is intended to ensure that all components of a plant meet the prescribed technical standards. Furthermore, ZEREZ facilitates communication between network operators, manufacturers, and plant operators.

The ZEREZ requirement is, for once, not another bureaucratic hurdle, but a sensible step towards standardizing and accelerating the grid connection process for renewable energy plants. Although the introduction of ZEREZ initially involves some effort, the long-term benefits of a more efficient, standardized grid connection process outweigh this. It is therefore not "bureaucratic madness," but a necessary modernization and simplification to support the expansion of renewable energies, which significantly contributes to reducing red tape. Previously, plant operators had to submit extensive documentation and certificates for their components when connecting to the grid. This was often a time-consuming and bureaucratic process. With the introduction of ZEREZ, this changes fundamentally. In the future, the ZEREZ registration number (ZEREZ ID) will suffice.

The ZEREZ requirement marks an important step towards the digitalization and standardization of the German electricity grid. For operators of photovoltaic systems, especially in the private sector, it is crucial to familiarize themselves with the new requirements early on. Careful planning and coordination with installers and manufacturers can help avoid delays in grid connection.

ZEREZ not only improves grid security but also paves the way for a more efficient and sustainable energy supply. Plant operators should see the introduction of the ZEREZ obligation as an opportunity to optimize the processes surrounding their photovoltaic systems and contribute to the energy transition.

New obligations for operators of photovoltaic systems

With the implementation of the ZEREZ obligation, operators of photovoltaic systems are required to register all relevant unit and component certificates for their systems in the central register. This obligation applies to both existing and newly installed systems. The following specific requirements must be observed:

• Transmission of the ZEREZ registration number: Operators must transmit the corresponding ZEREZ number of their components to their network operator.
• Prerequisite for grid connection: Systems may not be connected to the grid without correct ZEREZ registration.
• Inverter registration: Especially for private PV systems in the low-voltage network, it must be ensured that the inverter is properly registered.

Failure to comply with these requirements may result in grid connection being refused. Operators should therefore ensure early on that all relevant steps are followed.

Objectives of the ZEREZ obligation

The introduction of the ZEREZ registry pursues several central goals:

• Standardization and simplification: The grid connection process is standardized and accelerated through the digitization of certificates.
• Transparency and security: Network operators can check the conformity of the systems more quickly and easily, which improves network security.
• Efficient error prevention: Centralized data collection helps to identify faulty or insufficiently certified components at an early stage.

In this way, ZEREZ makes a significant contribution to the modernization and increased efficiency of the energy supply in Germany.

Special requirements for larger plants

For installations with a feed-in capacity exceeding 270 kW, stricter requirements apply. These installations require a comprehensive installation certificate that demonstrates the technical suitability of the entire system. Operators of such installations must ensure that:

• All unit certificates for the components (e.g., inverters, battery storage) are stored in ZEREZ.
• Additionally, a plant certificate is available, which includes the feed-in capacity and other technical details.

Important information for private plant operators

Private operators of photovoltaic systems, which are usually operated in the low-voltage network, should pay particular attention to the following points:

1. Registration by the installer: It is generally the responsibility of the installer or manufacturer to take the necessary steps for ZEREZ registration. Operators should clarify this in advance.
2. Inverter verification: The inverter is the central element that must be registered in ZEREZ. Operators can verify the registration themselves via the ZEREZ database.
3. Early planning: To avoid delays in network connection, it is advisable to clarify the registration before installation.

How do you verify the registration of an inverter in ZEREZ?

Checking whether an inverter is correctly registered in ZEREZ is a simple process that can be done online. Proceed as follows:

1. Accessing the ZEREZ registry

• Visit the official ZEREZ website at https://zerez.net.
• Basic information can be viewed without registration.

2. Use the search function

• Enter the manufacturer and model of your inverter into the search box.
• The database shows you whether the inverter is registered and which certificates are available.

3. Fix problems

• If your inverter is not registered, contact the manufacturer or your installer.
• When performing new installations, ensure that only registered components are used.

Which systems and components require ZEREZ certificates?

The ZEREZ requirement affects a wide range of power generation plants and their components. Here is an overview:

1. Installations in the low-voltage network

• Typical private photovoltaic systems for personal use.
• Usually, only a unit certificate for the inverter is required.

2. Installations in the medium, high and extra-high voltage grid

• Larger plants require additional certificates for individual components.
• Plant certificates are required for a feed-in capacity exceeding 270 kW.

3. Performance limits

• Systems with a total output of up to 500 kW and a maximum feed-in capacity of 270 kW do not require a system certificate. Simple proof is sufficient, which can primarily be provided by certificates from the manufacturers of units and components.
• Systems exceeding these performance limits must undergo comprehensive certification.

4. Additional components

• Battery storage systems.
• Combined heat and power plants and other electricity generation facilities.

Advantages of the ZEREZ obligation for operators and network operators

The introduction of ZEREZ brings numerous advantages, including:

• Time saving: Digital data collection significantly speeds up the grid connection process.
• Improved communication: Network operators can access relevant information and make decisions more quickly.
• Increased reliability: Faulty or insufficiently certified systems are detected early, which improves network security.

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What is meant by the term "ZEREZ obligation" and why is it relevant for photovoltaic systems?

The term "ZEREZ obligation" refers to the requirement that all photovoltaic systems (PV systems) and other electricity generation plants must be registered in a central register called ZEREZ ("Central Register for Unit and Component Certificates") from February 1, 2025. This entails the obligation to upload all necessary certificates for the systems and their components. This applies particularly to the inverter for private individuals and additional system components for larger PV projects. This registration allows grid operators to check more quickly and reliably whether a system is functioning correctly and in compliance with current regulations. This increases grid security and simplifies the grid connection process.

Why are photovoltaic systems becoming increasingly important in the context of the energy transition?

Photovoltaics is a key technology for a sustainable energy supply, as it produces emission-free electricity using sunlight. Over the years, PV modules have become more efficient and cost-effective, which has greatly accelerated their adoption. Given the efforts to increase the share of renewable energies and reduce CO₂ emissions, more and more homes and businesses have installed photovoltaic systems. However, this development also requires appropriate regulations to ensure grid stability and improve the interaction between electricity generation, grid operators, and consumers. For this reason, legal requirements such as the ZEREZ obligation exist, which aim to promote transparency and reliability throughout the entire energy system.

What exactly is ZEREZ and how does this registry work?

ZEREZ stands for "Central Register for Unit and Component Certificates" and represents a large, nationwide database. It centrally records certificates for power generation plants and their components, such as inverters, battery storage systems, and transformers. Operators are required to register all necessary certificates in ZEREZ. Based on these entries, grid operators can precisely verify whether a planned PV system meets the relevant safety standards and technical specifications. The information in the register is managed digitally and made available centrally. This simplifies the grid connection process, reduces potential queries, and increases the security of the entire power grid.

What are the goals of introducing ZEREZ?

The introduction of ZEREZ serves several purposes. First, it aims to "increase the security and reliability of the electricity grid" by allowing only systems whose components are certified and registered in ZEREZ to feed into the public grid. Second, it "standardizes and accelerates the grid connection process" because the required documents are stored centrally and can be accessed directly by grid operators. Third, it creates greater transparency for both PV system operators and manufacturers and grid operators. These structured processes lay an important foundation for the further growth of renewable energies.

What specific obligations will operators of PV systems have from February 1, 2025?

By the deadline of February 1, 2025, operators of photovoltaic systems must ensure that all essential certificates for their system – for example, the unit certificate for the inverter – are registered in ZEREZ. The law also stipulates that system operators must provide their ZEREZ registration number to the grid operator. Without this registration, the photovoltaic system cannot be connected to the grid. Even systems that have been in operation for some time must be retroactively registered if this has not already been done. Private operators, especially those in the low-voltage sector, should therefore check early on whether their documentation is complete and whether the inverter they are using is correctly registered.

What are the consequences of ignoring the ZEREZ obligation?

Operators who fail to register their systems with ZEREZ by the deadline face significant consequences. The grid operator can refuse to connect a new or even an existing system if all required certificates are missing. This can lead to lost revenue if the PV system is not permitted to feed into the grid. A system that is already connected but not properly registered may even be temporarily disconnected from the grid. Therefore, it is advisable to ensure compliance with ZEREZ regulations as early as possible. This is the only way to guarantee smooth system operation and avoid financial losses.

What types of installations are subject to this registration requirement?

In principle, all types of electricity generation plants are affected. This includes photovoltaic systems on private homes as well as larger solar parks or commercial installations. The regulations also cover plants that feed into medium-, high-, or extra-high-voltage grids. Furthermore, the registration requirement applies to other renewable and conventional generation methods, such as combined heat and power plants (CHP) or battery storage systems. It is important that every component that is significantly relevant to the operation and security of the electricity grid is registered in the ZEREZ database. This includes the unit certificate of the inverter as well as – depending on the plant size – comprehensive plant certificates and documentation for transformers or other technical equipment.

What distinguishes unit certificates from plant certificates?

Unit certificates typically refer to individual components, such as the inverter of a PV system. They certify that this individual component complies with specific standards and technical guidelines. System certificates, on the other hand, are primarily required for larger projects. They cover the entire system, including all connected components, and confirm their proper interaction. For a feed-in capacity exceeding 270 kW, but with a maximum installed capacity of 500 kW, a comprehensive system certificate is often required. For smaller, privately owned PV systems, a unit certificate is usually sufficient.

What role do battery storage systems play in this context?

Battery storage systems are enjoying increasing popularity because they can store excess solar power and release it when needed. This not only improves self-consumption rates but also contributes to grid stability. From February 1, 2025, such storage systems must also comply with the applicable certification guidelines and be registered in the ZEREZ database. The reason for this is that an improperly installed or technically inadequate storage system could compromise grid security. Operators should therefore ensure that their chosen storage system has the necessary certifications and is registered in a timely manner.

How can operators check if their inverter is already registered in ZEREZ?

The easiest way to find this information is via the official website zerez.net . There you'll find a search function where you can enter the manufacturer and the specific model of the inverter. If the device is listed, a ZEREZ ID will be displayed. If you can't find an entry, you can contact the manufacturer or your installer and ask about the registration process. It's also possible that older documents need to be updated or that an entry is still being processed. If you're still in the planning phase, it's advisable to only select inverters that are already registered.

How does ZEREZ simplify the grid connection process?

Thanks to the centralized storage of certificates in ZEREZ, network operators no longer need to request individual documents from each operator or engage in lengthy correspondence. Instead, they can immediately check online whether the components used from a specific manufacturer comply with current standards. This saves time and speeds up the verification process. At the same time, it provides the plant operator with clear guidance on which documents are required. This is particularly helpful when multiple components (e.g., inverters, battery storage, and other technical components) are working together, as ZEREZ offers a standardized assessment basis.

What steps should operators of new plants consider during the planning phase?

Anyone planning a new PV system should familiarize themselves with the requirements for certificates and ZEREZ registration early on. The following steps are helpful:

1. Create a plant concept: Define the size and performance of the planned plant with regard to self-consumption or possible feed-in.
2. Select a specialist company: Hire installers who already have experience with ZEREZ and the associated certifications.
3. Select components: For inverters and battery storage, choose models that are easy to register and already ZEREZ-compliant.
4. Inform network operators: Contact your local network operator early and clarify the registration process.
5. Check documentation: Ensure that all certificates for the register are available.
6. Time planning: Arrange for registration in ZEREZ in good time to avoid delays in network connection.

Does this registration requirement also apply to existing PV systems?

The registration requirement applies to existing electricity generation plants only in certain cases:

In case of major changes

• If a power generation plant (type C or D) is modernized or modified so extensively that the grid connection agreement needs to be fundamentally revised.

By decision of an authority

An authority can stipulate that an existing installation must comply with all or certain requirements of the regulation. This happens, for example, when the grid operator makes proposals to accommodate changing grid requirements (such as increased renewable energy).

More information here:

• The regulation on the verification of electrotechnical properties of energy installations (NELEV) states: This regulation applies to generation plants that are already connected to an electricity supply network at the time this regulation enters into force only under the conditions of Article 4 of Regulation (EU) 2016/631.
• Article 4: Existing electricity generating plants are subject to the requirements of this Regulation only in certain cases.

What challenges can arise when switching to ZEREZ?

One potential hurdle lies in obtaining missing certificates. With older systems, it's not always guaranteed that all components meet current technological standards. If relevant documents are missing, it may be necessary to contact the manufacturer or installer. Another issue concerns coordination between the various parties involved: network operators, installers, manufacturers, and system operators must work closely together for a smooth process. However, once this process is established, all parties benefit from faster and more efficient registration.

What advantages do private operators gain from the ZEREZ obligation?

At first glance, the ZEREZ requirement seems like an additional bureaucratic burden. Nevertheless, it offers tangible advantages for private operators:

1. Faster network connection: Since all the necessary information is available in a central database, the network connection can be checked and approved more quickly.
2. Increased security: Only certified devices are listed in the register. This reduces risks caused by faulty technology or improper operation.
3. Simplified documentation: All relevant documents are stored centrally, which can be useful in the event of maintenance, damage or system modifications.
4. Future-proof: Anyone who operates their plant in accordance with the ZEREZ specifications meets the requirements of current and likely future regulations within the framework of the energy transition.

What benefits does the energy industry as a whole derive from ZEREZ?

For the energy sector, ZEREZ primarily offers planning certainty and increased efficiency. Network operators gain an improved data foundation, enabling them to plan their networks more precisely and coordinate the steadily growing share of decentralized generation plants. Looking ahead to a future where electricity is increasingly produced and consumed regionally, such a register makes it possible to map complex feed-in structures. A growing number of private individuals and businesses can thus be integrated into the electricity grid without compromising security and stability. This promotes the growth of renewable energies and facilitates sector coupling, for example, towards heating or e-mobility.

What happens if the technical situation of a system changes, for example by replacing an inverter?

In this case, the newly installed inverter must be registered again in ZEREZ if it is not already listed. Any component change that affects the operation of the system therefore requires updated documentation. This ensures that it is always clear which types of equipment are in use and that the components comply with legal standards. A key advantage is that only one registration per model is required. If the inverter manufacturer is already listed, the relevant entry can be accessed directly, and the serial number of the new unit can be added.

Why are larger facilities in particular affected by more comprehensive certificates?

Larger installations with high feed-in capacities have a greater impact on the electricity grid than smaller ones. Therefore, legal regulations stipulate that installations with a feed-in capacity exceeding 270 kW require a comprehensive installation certificate. This certificate covers the entire system, including modules, inverters, switching and protective devices, and, where applicable, transformers. This ensures that the interaction of all components remains stable and safe, even under higher loads. In contrast, a unit certificate is usually sufficient for smaller installations, as their impact on grid stability is more manageable.

To what extent are combined heat and power plants and other generation facilities also affected by the ZEREZ obligation?

Combined heat and power plants (CHP plants) and other types of power plants, such as wind turbines or biogas plants, must also comply with the ZEREZ regulations. If they feed electricity into the public grid, they are subject to identical obligations regarding certification and registration. Since CHP plants often produce both heat and electricity, it is also necessary to verify which technical and safety requirements they must meet. The register ensures uniform standards in this regard, regardless of the technology used.

How will the transition to the cut-off date of February 1, 2025 be structured?

Officially, all newly connected power generation plants must comply with ZEREZ requirements from February 1, 2025. Operators of older plants that are not yet registered will face an obligation to catch up. While grid operators may initially grant a grace period to distribute the significant processing workload, all owners of power generation plants should act promptly. Those who ignore the regulations risk shutdowns or at least temporary outages. Therefore, it is advisable to familiarize yourself with the necessary documents and certificates before this date.

To what extent does the ZEREZ obligation contribute to the modernization and digitalization of the energy sector?

The introduction of a central, fully digital register is a key building block for modernizing the energy sector. Instead of paper documents and scattered datasets across various authorities or manufacturers, ZEREZ consolidates all information in one place. This accelerates the grid integration of PV systems and other power generators. Operators, manufacturers, and grid operators communicate more effectively because they have access to the same datasets. In the long term, this system can be expanded to better integrate intelligent controls, smart grid concepts, and future technologies.

Why is it sensible to also focus on future technologies such as smart meter gateways or charging stations?

The energy sector is undergoing dynamic development, with many new components becoming relevant. Smart meter gateways enable precise measurement and control of electricity demand. Charging stations for electric vehicles generate additional electricity demand and may need to be integrated with the home grid or other generation sources. When these new components are also certified and documented in the same data register, a comprehensive picture of the energy system emerges. This facilitates safe operation for both grid operators and end consumers and ensures that all units are compatible and reliably connected.

What practical tips are there for owners of smaller PV systems in their own homes?

Anyone who operates or plans to operate their own small rooftop system should specifically consider the following points:

1. Current documents: Carefully keep all certificates for the inverter and any storage systems.
2. Manufacturer support: If there are any uncertainties or documents are missing, contact the manufacturer, as they can usually provide documentation in digital form.
3. Involve a specialist company: Many craft businesses offer support with ZEREZ registration or can handle it for you.
4. Keep deadlines in mind: All entries should be completed by February 1, 2025 at the latest.
5. Choose reliable components: Manufacturers whose products are already ZEREZ-listed generally offer greater planning security.

Why do manufacturers also benefit from the ZEREZ requirement?

Manufacturers who successfully list their products in ZEREZ gain a competitive advantage. Operators and installers rely on certified components to guarantee a smooth grid connection. Products that are not listed or require an overly complicated certification procedure may become less attractive. Furthermore, the clearly defined guidelines and the central register promote product quality, as manufacturers must provide valid certificates for their entire product range. This contributes to increasing the reliability and competitiveness of the industry as a whole.

What lessons can be learned from the ZEREZ obligation for the further development of renewable energies?

The ZEREZ mandate demonstrates the importance of clear framework conditions, transparency, and standardization for the smooth growth of renewable energies. Those who introduce new technologies in the future, such as smart storage systems, cross-sector solutions, or advanced metering and control devices, can draw on the experience gained with ZEREZ. A central register facilitates market access for new products, accelerates approvals, and establishes reliable standards that could be applied both in Germany and potentially across Europe. In this way, the ZEREZ mandate could serve as a model for further digital solutions in other energy sectors.

What is a proven process for optimally preparing for the deadline of February 1, 2025?

Those who already operate a PV system or are planning to build one can organize themselves as follows:

1. Inventory: Review current documents and certificates and check for completeness.
2. Contact the installer: Ask the specialist company if they can handle the registration and what documentation is required.
3. Obtain information from the manufacturer: If something is missing, the manufacturer can often be contacted directly to obtain updates.
4. Inform network operators: Clarify which additional documents the network operator requires or in what form the ZEREZ registration number must be provided.
5. Meet deadlines: Make sure you don't start the registration at the last minute so that any problems can be resolved before the deadline.
6. Future planning: When planning expansions (e.g., battery storage, e-charging station), check in advance which certificates are required.

What role does politics play in the introduction of ZEREZ?

Policymakers have recognized that the expansion of renewable energies requires a clear and reliable framework. The introduction of ZEREZ establishes binding standards and norms that simplify the work of grid operators and serve as guidance for other operators. Such policy measures ensure that the electricity grid remains protected from unnecessary risks and increase public acceptance of solar power and other renewable technologies. By enacting binding regulations, the expansion of renewable energies is promoted while simultaneously ensuring that this expansion proceeds in an orderly and regulated manner.

How does the ZEREZ system support operators in the event of maintenance work or damage?

If the system or one of its components is correctly registered in ZEREZ, all relevant data is stored centrally in digital form. During repairs or maintenance, the responsible technician can see at a glance which components were originally installed and which standards must be met. This significantly simplifies the search for compatible spare parts and reduces system downtime. In the event of damage, insurance claims can also be processed more quickly because it is easy to verify which certified components were installed and whether all safety requirements were met.

Is the ZEREZ requirement merely a bureaucratic obstacle, or does it also have long-term advantages?

The ZEREZ requirement may initially seem like a bureaucratic hurdle, as operators now have to handle registrations when previously a simple grid connection application sufficed. However, in the long run, the advantages outweigh the disadvantages, because standardized processes and transparent certifications make the entire system more reliable and efficient. This creates a kind of quality control for the growing renewable energy market. As a result, the foundation is laid for integrating new technologies more quickly, designing precise grid expansion plans, and driving the energy transition forward even more effectively.

What are the prospects for the near future once the ZEREZ obligation is fully implemented?

Once the ZEREZ mandate is fully in effect and all affected installations are registered, a comprehensive database of the entire decentralized power generation fleet will be available. This will allow for more efficient grid management and control when needed. Furthermore, future innovations, such as artificial intelligence in load management or automated balancing reserves, could be implemented more easily due to the higher data quality and greater accessibility. In a networked world of energy generation and consumption, it is essential that all components work together seamlessly. ZEREZ provides precisely the necessary infrastructure and transparency for this purpose.

Finally, what should operators do to prepare their PV system for the ZEREZ obligation?

Early information gathering and collaboration with trusted experts are crucial. Operators should familiarize themselves with their existing documentation and contact their grid operator, installer, or manufacturer now. This will clarify whether all necessary certificates are present or if anything else needs to be provided. Those planning a new installation are well advised to use only products whose ZEREZ compliance has already been verified. This head start ensures that their contribution to the energy transition is not hampered by formal hurdles and guarantees trouble-free operation in the long term.

Does the ZEREZ requirement also apply to balcony power plants?

Yes, the ZEREZ requirement also applies to balcony power plants.

For which types of plants is ZEREZ mandatory?

• Photovoltaic systems: Both private and commercial systems must be registered in the ZEREZ.
• Wind energy plants: Wind turbines are also subject to the ZEREZ obligation.
• Battery storage systems: Registration is also required for energy storage systems.
• Combined heat and power plants (CHP): CHP plants and other conventional generation plants must also be recorded in the ZEREZ.
• Other power generation plants: This includes, for example, hydroelectric power plants and biogas plants.

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