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What is a DNO application for Solar Panels?
DNO stands for Distribution Network Operator, which is the company responsible for maintaining the electrical distribution network in your area. The DNO connects homes and businesses to the electricity network.
When you choose to install solar panels on your home or your commercial property, you’ll need to submit a DNO application. The application will make sure that you’re meeting safety standards and that your system won’t overload the network when you connect to the national grid.
Without proper approval from the DNO, you could risk causing damage to your solar system and the stability of your connection to the grid. There are multiple types of DNO applications that we’ll go through later in this blog.
What is the role of a distribution network operator?
The role of a DNO in the UK is responsible for a range of things when it comes to your solar installation:
Grid connection and approval process
When you install solar panels, you’ll need to connect them to the grid, this is so you can sell your unused power back. The DNO is responsible for managing and approving the connection of your solar system to the grid. They look at whether the local network can cope with the extra electricity your solar panels generate without causing issues for the grid.
Application process (G98 and G99)
The DNO is responsible for processing applications to connect solar systems to the grid, including reviewing their capacity, the location of the solar install, and any technical specifications. For home systems, the application might fall under the G98 guidelines.Larger commercial systems may need a G99 application. You can see more on the difference between G98 and G99 below.
Monitoring and managing grid stability
As more homes and businesses install solar panels, DNOs need to make sure that the grid is balanced. They manage voltage regulation and load balancing. This stops issues like overloading or instability, especially during peak generation, when many homes may be producing excess solar energy.
Upgrading the local network
If your local area has an increased need for solar, the DNO is responsible for upgrading the local distribution networks to handle extra demand. This might include adding more transformers, improving lines, or even creating new infrastructure to carry the extra electricity solar panels generate in your area.
Disconnection and maintenance
For any issues including equipment failure or safety concerns, the DNO disconnects systems from the grid. They’re also responsible for any maintenance and repairs of anything related to connection infrastructure to make sure that everything is working properly.
When to submit a DNO application for solar panels
If you're installing solar panels, you might need to submit a DNO application. This is mostly required for larger systems or in areas where the grid could be impacted. Here's three scenarios in which you might need to submit an application:
1. Solar system size
If your solar system is over 3.68kW you’ll need to submit a DNO application. The size of your system matters, and it can depend on whether you're in a single-phase or three-phase area.
2. Local grid connection rules
If your solar installation could affect the local grid's stability or if you live in an area with a weak grid connection, a DNO application is necessary.
3. Inverter type
The type of inverter used in your system is important. Some inverters need approval because they can affect how the solar energy is fed into the grid.
The difference between G98 and G99 applications?
Earlier in the blog we mentioned that there were two types of DNO application - G98 and G99. Here are the key differences between the two and what they mean:
What is a G98 solar application?
The G98 solar application is generally for connecting smaller generation systems to the electrical grid. G98 is a set of guidelines the Energy Networks Association (ENA) created to make sure that solar systems under 16kW (up to 16A per phase) meet safety and technical requirements before being connected to the grid. Domestic solar panel systems are typically under 3.68 kW, making them fall under this category.
What is a G99 solar application
Larger solar systems (over 16kW) that are being connected to the grid need a G99 application. It makes sure the system meets the technical and safety standards to stop any disruption to the local electrical network.
If your solar installation exceeds 16kW, you'll need to submit a G99 application to the Distribution Network Operator (DNO). This process makes sure your system won't cause issues like voltage fluctuations or grid instability.
What’s the key difference between a G98 and a G99 solar application
The main difference between G98 and G99 solar applications is the system size:
G98 is for smaller solar systems (up to 16kW)
G99 is for larger solar systems (over 16kW)
In addition to size, G99 applications are more detailed, as larger systems have a greater potential to impact grid stability. G99 also involves more comprehensive checks on the system's impact on the local electricity network, making sure it's safe to connect.
For homes in the UK, a G98 application is more likely. This is because most domestic solar systems are under 16kW, which falls under G98. These systems are typically smaller and less likely to cause grid stability issues, so the G98 application is enough for most homes.
What happens if I install solar without submitting a DNO application?
If you install solar panels without submitting a DNO application, you could face several issues. First, you may be breaking the law. The DNO needs to approve your system to make sure it’s safe and won’t impact the local electricity grid.
Without approval, you could have problems connecting to the grid or even face issues with house insurance and issues when selling your property in the future. They may also disconnect your system if they find it non-compliant.. This could lead to wasted time and money. If you don’t comply with DNO approval, the rest of the installation likely won't meet standards.
Alongside the financial element of not submitting a DNO, it could also lead to:
Safety hazards: Without proper approval, your solar system may not meet safety standards. This could lead to electrical hazards, such as fires or electric shocks, which put your home at risk.
Increased likelihood of system failure or damage: A system that’s not approved could be poorly integrated with the grid, causing issues like voltage spikes or power surges. This could lead to damage to your solar panels, inverters, or other electrical appliances in your home.
How long does the DNO approval process take?
The DNO approval process can vary in length, but generally, it takes:
10-15 working days for a G98 application (smaller systems)
Up to 60 working days for a G99 application (larger systems)
These timelines can change depending on:
System complexity: Complex systems or special requirements may take longer to assess
DNO workload: High volume of applications can cause delays
Grid conditions: Approval processes may take longer in areas with grid constraints or issues
Who is responsible for submitting a DNO application?
It’s typically your solar installer that will submit your DNO application. Installers are the experts. They’ll be familiar with the process, the documents you need, and the technical specifications of the application.
If you choose to manage your installation on your own, you can submit the application yourself, though it’s recommended to rely on professional help.
What information is required when submitting a DNO application?
You'll need to provide several key pieces of information to make sure that the system is assessed properly for grid connection. Here's a breakdown of what's required:
Inverter specifications: This includes the model and power output of your inverter, along with details on its capabilities. The inverter is a crucial component as it converts the solar energy into usable electricity.
Generation capacity: You’ll need to provide the total generation capacity of your solar system, which refers to how much electricity the system can produce under ideal conditions.
Grid connection details: This includes how your solar system will be physically connected to the local electricity grid. The DNO needs specifics about the connection point, whether it's a single-phase or three-phase connection.
System design: A detailed electrical layout of your solar installation is needed. This includes the placement of solar panels, wiring diagram, and any other electrical components. It gives the DNO a complete picture of how the system will be set up, helping them look for any potential safety or compatibility issues.
How much does a DNO application cost?
The cost of a DNO application depends on a few factors, but generally, it ranges from £50 to £500. For smaller, straightforward systems, the fee will usually be at the lower end of the scale. If your solar installation is larger or more complex, the cost can be higher. This can include extra assessments or checks, especially if the grid in your area has limited capacity.
Can the DNO reject my application?
Yes, the DNO can reject your application if your system does not meet their standards or if there are issues with the local grid. Common reasons for rejection include:
Grid capacity: If the local grid cannot handle additional generation
Safety concerns: If your system doesn’t meet safety requirements
If rejected, you can appeal the decision, provide extra information, or make adjustments to your system to meet DNO standards.