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Install Solar Panels and produce your own electricity at home. But when you hook your system into the grid, there’s some planning that needs to be done. Your Distribution Network Operator (DNO) will need to be aware of your installation. Possible approval prior to work depending on size.
The DNO Solar Panel Application assists in safeguarding local electricity networks. It checks whether your equipment can connect safely. Most small domestic systems follow G98 requirements. Larger installations usually need a G99 application.
Battery storage can also affect your connection requirements. Export limits and network upgrades may sometimes become necessary. This guide is written in a simple manner to explain this process. It includes information on applications, approval letters, cost, timeframe and frequently asked questions.
1. Understanding Your Local Electricity Network
What does DNO mean?
DNOs are Distribution Network Operators. Your DNO is responsible for all electricity connected to your property. It supports the cables, substations and equipment which provide electricity.
Your electric company plays another role. It is a company that sells electricity and runs your energy tariff. The DNO manages the physical network connecting your property. Therefore, your supplier cannot approve your solar grid connection.
Your local DNO depends on your property’s location. You can identify it using your postcode. The Energy Networks Association provides an online network operator checker.
Why does the DNO need to know about solar panels?
Solar panels produce electricity during daylight hours. Your property can use this electricity before importing grid electricity. Any unused electricity may flow into the local network. This process is called exporting electricity.
Solar export can affect local voltage and electricity flows. The DNO must check whether its network can support your system.
This matters when several properties export electricity simultaneously. Their combined output could affect local network conditions. The DNO therefore assesses your proposed generation and export capacity. This helps maintain a safe electricity supply.
2. Does Every Solar Installation Need DNO Permission?
Most grid-connected solar installations require DNO notification or approval. However, notification and prior approval are different processes. Some small installations qualify for G98. Their installers usually notify the DNO after commissioning.
Larger installations generally require a G99 application. The DNO must normally approve these before installation. Your installer should identify the correct route before work starts.
The process also could be used for battery storage. Electricity is able to be exported from batteries connected via inverters.Electrical export is possible from batteries connected via inverters. Even systems designed for self-consumption need proper assessment. Their equipment could still export under certain conditions.
What determines the correct application?
The DNO considers your equipment and proposed connection.
Important details include:
- Inverter rating and operating characteristics
- Total generating capacity
- Single-phase or three-phase electricity supply
- Battery inverter specifications
- Maximum permitted export
- Existing generation at your property
- Local network capacity
- Electrical protection arrangements
The number of solar panels alone does not determine approval. Two solar PV systems may have different panel counts. Yet, their inverter ratings could be similar. The inverter’s electrical output is therefore especially important.
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3. G98 and G99: Choosing the Correct Route
G98: Smaller generating systems
G98 generally covers compliant installations up to 16A per phase. At 230V, this equals approximately 3.68kW per phase. Many standard domestic solar systems fall within this limit. Under G98, prior DNO approval is usually unnecessary. However, your installer must notify the DNO after commissioning. The notification normally needs submitting within 28 days. Your installer should provide the required technical details. The DNO can then record the new generating equipment.G99: Larger or more complex installations
G99 generally applies when equipment exceeds G98 limits. It can cover larger domestic systems and commercial solar projects. Your installer submits the G99 application before installation. The DNO assesses the proposed grid connection. The DNO may request further technical details. It may also identify restrictions or necessary network work. You should wait for the required approval before proceeding.G98 versus G99: Quick comparison
| Feature | G98 | G99 |
| Typical installation | Smaller domestic solar | Larger domestic or commercial systems |
| Common threshold | Up to 16A per phase | Above applicable G98 limits |
| Approximate single-phase threshold | 3.68kW per phase | Above 3.68kW per phase |
| Main process | Notification after commissioning | Application before installation |
| Prior approval | Usually unnecessary | Usually required |
| Technical assessment | Generally simpler | May require detailed assessment |
| Who handles paperwork? | Usually your installer | Usually your installer |
| Possible restrictions | Export controls may apply | Export limits or network works may apply |
4. What About Solar Batteries, Heat Pumps and EV Chargers?
Battery storage can change your property’s electrical connection. A battery stores electricity for later household use. However, its inverter may also export electricity. The DNO must consider the combined generating equipment. Your installer should assess both solar and battery specifications.
A heat pump uses electricity rather than generating it. Its connection may still need checking for electrical capacity. EV chargers can increase your property’s electricity demand. They do not automatically require a G98 or G99 application.
However, larger projects may involve several electrical changes. Your installer should assess the complete installation.
Do batteries always require G99?
No, it does not need to be applied to any battery installation. The process applicable will vary with the equipment and connection. Your installer must check the relevant engineering requirements.
Some batteries operate alongside existing solar inverters. Others use separate inverter equipment. The DNO needs accurate information about the proposed arrangement. This includes potential export through each relevant inverter.
5. What Information Goes Into a DNO Application?
Your installer usually prepares the application paperwork. The required details depend on the system and application type.
A typical application may include:
- Inverter manufacturer, model, and rated output
- Solar PV generation capacity
- Battery equipment details
- Single-phase or three-phase supply information
- Property address and connection details
- Proposed export capacity
- Electrical layout and wiring diagram
- Protection and control equipment details
- Relevant installer and equipment certifications
A G99 application may require additional technical documents. Your installer should confirm which documents are necessary. You generally do not need to submit your electricity bill. However, your MPAN may help identify your electricity connection. Your MPAN is a reference for your electricity supply. It can appear on your electricity bill.
6. What Happens After the DNO Receives Your Application?
The DNO reviews the proposed connection and its network impact. It may accept the design without additional restrictions. Alternatively, it may request changes or further information. There are three common outcomes.
Outcome One: The DNO accepts your proposed system
The DNO agrees to the requested connection arrangements. Your installer can proceed once required approvals are complete. The connection may not require additional network work. However, approval does not guarantee that every project has zero charges. Your installer should confirm any applicable fees.
Outcome Two: The DNO requires an export limitation
The local network may not support your system’s full export. The DNO may therefore restrict the electricity exported. Your installer can use suitable export limitation equipment. This may involve requirements under G100.
The system can still generate electricity for household use. However, it must follow the approved export limit. Some arrangements may require testing or witnessing. Additional charges may apply, depending on the DNO’s requirements.
Outcome Three: The DNO requires network upgrades
The current power network might not have enough capacity. The DNO may need to be reinforced or upgraded. This may include modifications to cables, equipment or supply arrangements.
A three phase connection may be necessary for some properties. This can add to the project’s expenses and timeline. The DNO should clarify the works and charges needed. Your installer will then be able to discuss how to implement these solutions for you.
7. What Is G100 and Why Does Export Limitation Matter?
G100 relates to equipment that limits electricity export. It can help installations meet the DNO’s approved export conditions. For example, your solar system might generate more electricity than permitted for export.
An export limitation device controls the electricity sent into the grid. Your property can still use available solar generation. A battery may also store surplus electricity.
The equipment however should operate within the agreed limit. Your installer should be able to tell you about the planned export control arrangement. The DNO might ask for proof that the system is functioning properly.
8. How Long Does DNO Approval Take?
| Application route | What happens | Planning guidance |
| G98 | Installer notifies the DNO after commissioning | Notification is normally submitted within 28 days |
| G99 | DNO assesses the proposed connection before installation | Allow time for technical review and possible questions |
| G100 | DNO assesses export limitation arrangements | Timing depends on equipment and approval requirements |
| Network reinforcement | DNO arranges necessary network changes | Timescale depends on the work involved |
9. What Is a DNO Letter for Solar Panels?
A DNO letter for solar panel installation records the DNO’s response. Its wording depends on the application route. For G99, the DNO may issue an approval or connection offer. This confirms the agreed connection conditions. For G98, the DNO may acknowledge your notification. This records the installed generating equipment.
People sometimes call these documents a DNO certificate for solar panels. However, there is no single certificate format for every installation. Keep your DNO paperwork with your installation documents. You may need it when selling your home. It can also support questions about your grid connection.
How do I get a DNO certificate?
Ask your installer for the DNO’s written response. If you cannot find it, contact your installer first. They may hold the application reference and correspondence. You can also contact your DNO directly. Provide your property details and installation information. The DNO can explain which records it holds.
How do I check my DNO approval?
Start by checking your installer’s paperwork. Look for the DNO application reference and written response. For G99, check whether approval was issued. Also review any export limits or connection conditions. For G98, ask whether the notification was submitted. If necessary, contact your local DNO for confirmation.
10. What If You Install Solar Without Required DNO Approval?
Missing paperwork can also complicate future property sales. Buyers may request evidence of compliant installation and connection. Your eligibility for export payments may also depend on other requirements. For example, SEG incentives are based on checks by suppliers.
The impacts of insurance vary depending on insurance policies and situations. Review your policy and don’t assume that it is null and void. The best way to do this is to finish the appropriate DNO process. Request confirmation from your installer prior to commissioning.
Final Thoughts
A DNO application is crucial in the installation of solar. It assists to ensure a safe connection to your system. Typically, small systems will adhere to G98 notification requirements. Typically, larger systems require G99 approval prior to installation. The process may be impacted by battery storage and export controls.
Your installer should handle the paperwork, and explain the result. Ensure that you check with your DNO and the application for which it will be installed prior to installation. Don’t forget to ask for approval, export restrictions, and any network charges, either. This preparation can help your solar project to run smoothly.
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