Do I Need DNO Approval for Solar Panels?
Most solar panel and battery storage systems connected to the electricity grid must be registered with the local Distribution Network Operator, commonly known as the DNO.
Whether approval is required before installation depends on the size and design of the system. Smaller installations can often be connected first and notified afterwards, while larger systems normally require an application before they can be commissioned.
This guide explains when DNO approval is needed, what information must be submitted and how the process affects solar and battery installations in Scotland.
What Is a Distribution Network Operator?
A Distribution Network Operator is the company responsible for operating and maintaining the local electricity network that supplies homes and businesses.
The DNO does not sell electricity to you. Your electricity supplier handles your tariff and billing, while the DNO manages the cables, substations and network infrastructure that deliver electricity to the property.
When solar panels or battery storage are installed, electricity may flow from the property back into that network. The DNO must therefore be informed so it can confirm that the system is safe and compatible with the local grid.
Across most of central and southern Scotland, the DNO is SP Energy Networks. In the north of Scotland, it is generally Scottish and Southern Electricity Networks, known as SSEN.
Does Every Solar Installation Need to Be Registered?
Yes. A grid-connected solar installation must normally be registered with the relevant DNO.
However, registration does not always mean waiting for approval before the work begins.
The process usually falls into one of two categories:
G98: Connect and Notify
Smaller, fully type-tested systems operating within the G98 limits can normally be installed and then notified to the DNO.
G99: Apply Before Connection
Systems exceeding the G98 limits generally require a G99 application and DNO assessment before they are connected, unless an applicable fast-track or limited-export procedure is being followed.
SP Energy Networks describes G98 as applying to smaller generators below 3.68kW per phase, while G99 applies to larger generators above that level.
When Can Solar Be Installed Under G98?
G98 is commonly used where the aggregate registered capacity does not exceed 16 amps, or approximately 3.68kW, per phase.
For a qualifying single installation, the installer can normally:
- Fit and commission the system
- Confirm that the equipment is fully type tested
- Notify the DNO at or around the time of commissioning
- Submit the required installation information
This is often called Connect and Notify.
It is important to understand that the 3.68kW figure normally relates to the inverter or generating capacity assessed under the connection rules—not simply the total wattage printed on the solar panels.
A property could therefore have more than 3.68kWp of solar panels connected to a suitably designed 3.68kW inverter.
Official DNO guidance describes G98 as a simplified fit-and-notify procedure for fully type-tested installations of up to 16A per phase.
When Is a G99 Application Required?
A G99 application will generally be required where the system is capable of operating above the G98 threshold.
This may include:
- An inverter rated above 3.68kW on a single-phase supply
- Multiple inverters installed at the same property
- Solar PV combined with separate battery inverters
- Larger commercial solar installations
- Three-phase generation systems
- Battery storage exceeding the applicable connection limits
- An extension to an existing generation system
The DNO assesses the proposed system against the available capacity and operating conditions of the local network.
Depending on the design, the DNO may:
- Approve the application as submitted
- Approve it with an export restriction
- Offer a lower connection capacity
- Request additional protection or design information
- Identify network reinforcement work
- Issue a quotation for any necessary work
SP Energy Networks provides separate G99 application routes, including forms for systems below 50kW and recognised fast-track procedures for qualifying solar-and-storage arrangements.
Is DNO Approval Based on Panel Capacity or Inverter Size?
The connection assessment is not based solely on the combined wattage of the solar panels.
The DNO is primarily concerned with the electrical equipment connected in parallel with the network and how much power that equipment can generate or export.
The system assessment may consider:
- Inverter registered capacity
- Maximum export capability
- Number of phases
- Existing generation at the property
- Battery inverter capacity
- Type-tested protection
- Export-limitation equipment
- Local network conditions
For example, a 6kWp solar array connected to a 3.68kW hybrid inverter may still fall within a different connection route from a 6kW inverter, because the two systems have different maximum AC output capabilities.
The complete electrical design must therefore be assessed rather than relying only on the solar-panel capacity.
Do Battery Storage Systems Need DNO Approval?
Battery storage is treated as generating equipment because a battery inverter can discharge electricity into the property and potentially export power to the grid.
A battery installation must therefore be included within the DNO assessment.
This applies to:
- Solar and battery systems installed together
- Batteries added to an existing solar installation
- Battery-only installations
- AC-coupled battery systems
- Hybrid inverters with integrated battery storage
Where solar and battery storage use separate inverters, their aggregate generating capacity can affect the applicable connection process.
SP Energy Networks states that energy-storage connections exceeding 3.68kW per phase fall under G99 requirements.
Can Export Limitation Avoid Network Reinforcement?
In some cases, yes.
A system may use an approved G100 export-limitation scheme to restrict the amount of electricity exported to the network.
This can allow a property to have:
- A larger solar array
- A higher-capacity inverter
- More battery storage
- Greater power available for on-site consumption
- A controlled maximum grid export
For example, a system may be capable of supplying more than 3.68kW within the property while limiting export to an agreed level.
Export limitation does not automatically remove the need for a DNO application. The design and proposed export limit must still follow the applicable connection procedure and be accepted where required.
SP Energy Networks publishes an alternative connection route under which qualifying systems may use type-approved G100 equipment to limit export to 3.68kW per phase.
What Information Does the DNO Need?
The exact information depends on the connection route, but a submission may include:
- Property address
- MPAN electricity-supply number
- Inverter manufacturer and model
- Inverter capacity
- Solar-panel capacity
- Battery manufacturer and capacity
- Single-line electrical diagram
- Equipment type-test references
- Export-limitation details
- Site plan
- Existing generation information
- Proposed commissioning date
Accurate information is important because incomplete or conflicting details can delay an application.
Your installer should normally prepare and submit the technical documents on your behalf.
How Long Does DNO Approval Take?
A straightforward G98 installation does not usually require the same pre-installation waiting period because it follows the Connect and Notify process.
G99 timescales vary depending on:
- The system capacity
- The application procedure used
- Whether the equipment is fully type tested
- Local network constraints
- Whether export limitation is proposed
- Whether additional studies or reinforcement are required
- The DNO’s current workload
Some qualifying applications can follow a faster procedure, while more complex connections may take several weeks or longer.
For that reason, DNO requirements should be considered during the initial system design—not after the installation has already been arranged.
Can the DNO Refuse a Solar Installation?
The DNO may be unable to approve the exact capacity originally requested, but that does not necessarily mean solar cannot be installed.
Alternative options can include:
- Reducing the inverter capacity
- Applying an export limit
- Installing under a smaller connection arrangement
- Changing the system design
- Upgrading the electricity supply
- Accepting a network-reinforcement quotation
- Installing generation across three phases where appropriate
A competent designer should assess the DNO response and determine whether a practical alternative can achieve the customer’s objectives.
Is DNO Approval the Same as MCS Certification?
No. They are separate parts of the installation process.
DNO registration or approval concerns the connection of the generating equipment to the electricity network.
MCS certification confirms that an eligible installation has been designed and installed in accordance with the relevant MCS standards and scheme requirements.
A properly managed project may therefore involve:
- Technical system design
- DNO notification or application
- Electrical installation and commissioning
- MCS certification
- Handover documentation
- Smart Export Guarantee registration
Receiving an MCS certificate does not replace the need for the appropriate DNO process.
How Zero Carbon Manages DNO Applications
Zero Carbon assesses the grid-connection requirements as part of the technical design process.
We consider:
- Existing generation at the property
- Proposed solar capacity
- Inverter output
- Battery inverter capacity
- Single-phase or three-phase supply
- Expected household demand
- Export limitation
- Electric vehicle charging
- Heat-pump demand
- Future system expansion
Where a G98 connection is appropriate, we manage the required notification.
Where G99 applies, we prepare the technical information and submit the application to the relevant DNO. We can also assess export-limited and alternative connection options where the originally requested capacity is unavailable.
This helps ensure that the proposed system is not only technically capable, but also compatible with the electricity network and the customer’s long-term energy plans.
Frequently Asked Questions
Can I install solar panels without telling the DNO?
A grid-connected solar installation must normally be registered through the appropriate G98 or G99 procedure. The installer should manage this process.
Do I need DNO permission for a 3.68kW inverter?
A qualifying fully type-tested installation up to 16A per phase can normally follow the G98 Connect and Notify procedure rather than waiting for prior approval.
Do I need G99 for more than 3.68kWp of panels?
Not necessarily. Panel capacity and inverter output are different measurements. A system with more than 3.68kWp of panels may still use a 3.68kW inverter, subject to the full system design.
Does adding a battery require another application?
It can. A new battery changes the generating equipment connected at the property and should be assessed and notified to the DNO.
Can I export more than 3.68kW?
Potentially, but a larger export capacity normally requires a G99 application and agreement from the DNO.
Who submits the DNO application?
The solar or battery installer will normally prepare and submit the notification or application on the customer’s behalf.
Planning a Solar or Battery Installation?
A well-designed renewable energy system should account for the property, the customer’s energy use and the available grid connection from the beginning.
Zero Carbon provides engineering-led solar PV and battery-storage design throughout Scotland, including G98 notifications, G99 applications and G100 export-limitation solutions.
Speak to our team about your proposed installation.
