A DNO solar application lets you notify your local Distribution Network Operator that you plan to connect generation — like solar panels or battery storage — to the electricity grid.
You need a DNO application whenever your installation could affect the local network or exceed small‑scale thresholds, because approval keeps your system legal, safe, and eligible for export arrangements.
This guide covers the DNO application’s purpose, eligible applicants, pre-installation approval rules, step-by-step process, and key challenges. You’ll get actionable advice to secure a compliant grid connection smoothly.
What Is a DNO Application?
A DNO application is a formal request to your local network operator to connect or change a generation or demand installation. It includes technical details, location, and expected export or import so the network can assess safety and capacity.
Defining the Distribution Network Operator (DNO)
DNOs own, operate, and maintain local electricity wires and substations, delivering power to homes and businesses in a licensed region . Regulated by Ofgem, they oversee network integrity, fault response, and capacity planning — but do not sell electricity.
When installing solar, the DNO evaluates your equipment’s grid interaction: voltage control, fault levels, protection settings, and the network’s ability to absorb exports without instability .
The Purpose of a DNO Application
Submit the application to confirm the grid can safely accept your solar array or modified connection. It provides site coordinates, inverter specs, maximum export, and earthing details , allowing the DNO to:
- Approve the connection, request design changes, or impose limits (e.g., export curtailment).
- Require network reinforcement or formal agreements for large systems.
- Avoid delays and unexpected costs with timely, accurate submissions.
The Difference Between DNOs and Other Energy Entities
- Electricity suppliers: Bill you and trade energy; not involved in grid infrastructure.
- National Grid/ESO: Manage high-voltage transmission and national system balancing ; not local distribution.
- DNOs: Handle local low-voltage grid connections — the key contact for rooftop solar.
Why Is a DNO Application Important for Solar Installations?
A DNO application confirms whether your intended solar system can connect safely to the local distribution network. It also defines any technical limits, timelines, and costs you’ll face before work starts.
The application shares your equipment’s size and type, letting the DNO assess impacts on voltage, frequency, and fault levels. It confirms exports won’t cause over-voltage or transformer overload for nearby properties .
The DNO may impose export limits, require specific inverter settings (e.g., anti-islanding), or mandate monitoring equipment . These measures prevent power quality issues and outages, with written conditions for clear compliance.
Submission fulfills UK legal obligations for grid-connected generation/storage. Failing to notify can breach supply terms and local regulations .
Approval provides a connection offer or acceptance letter — critical for future inspections, warranty claims, building control certification, and export payments (e.g., SEG) .
DNO reviews identify site-specific constraints (e.g., export limits) that shape inverter and battery choices . Addressing these upfront avoids costly retrofits and keeps warranties valid (manufacturers/insurers require compliant connections) .
You’ll also get clear cost estimates for application fees, network reinforcement, or extra equipment — simplifying budgeting.
Who Needs to Make an Application to a DNO?
You must notify or apply to your local Distribution Network Operator (DNO) whenever your installation changes how much electricity you export or draw from the grid. This includes many rooftop PV systems, battery additions, and any upgrade that raises connected generation above the defined thresholds.
Residential Solar Panel Installations
- Small systems (≤3.68 kWp/16 A per phase): Only notification is required (via G98 form) within 28 days of installation .
- Larger systems: Formal application is mandatory if export capacity exceeds 16 A per phase (e.g., with battery storage) .
Thresholds vary by region and export frequency — confirm with your DNO. Key docs: inverter datasheet, system size, proposed export limit, and single-line diagrams .
Commercial & Industrial Solar Projects
Formal applications are almost always required for systems exceeding domestic limits. Installations over tens of kWp or connected to three-phase supplies trigger G99 processes and technical studies .
The DNO assesses network stability, harmonics, and fault current, requiring detailed electrical studies and capacity data . Plan for longer lead times (up to 65 working days for complex G99 applications) and potential network reinforcement costs.
Key Factor: System Size and Inverter Capacity
- Thresholds (3.68 kWp/16 A per phase for domestic) determine if notification or full application is needed .
- Provide inverter continuous export limits (not just peak DC size) — batteries can push exempt systems into the application category .
- Low local demand increases export constraints — confirm details with your DNO upfront.
The Role of Your Solar Installer in the Process
Certified installers (MCS or Competent Person Scheme registered) handle:
- Assessing if notification/application is required during design.
- Gathering docs and submitting G98/G99 forms on your behalf .
- Communicating with the DNO and addressing technical clarifications.
You remain responsible for ensuring permissions are in place pre-commissioning. Ask for a written plan outlining submission responsibilities, lead times, and potential extra costs .
Do I Have to Apply for DNO Approval Before Installing Solar Panels?
Requirements depend on inverter AC size and connection type: smaller domestic systems use a “notify-after-install” process, while larger/export-capable systems need pre-install approval .
The General Rule: Prior Notification or Approval
- Below threshold (≤3.68 kWp/16 A per phase): “Connect and notify” via G98 form within 28 days of installation .
- Above threshold: Apply before installation — the DNO assesses grid capacity .
Incorrect timing (installing without required approval) may force disconnection, delay commissioning, or incur extra costs .
Understanding”G98″ “G99” and “G100” Engineering Recommendations
- G98: For small systems (≤16 A per phase) — requires ENA-type-tested inverters and post-install notification .
- G99: For larger/export-capable systems — requires pre-install application with inverter specs, fault-ride-through capability, and test plans .
- G100: Guides export limitation schemes (ELS) and DNO coordination for embedded generation.
Exceptions and Simplified Processes for Smaller Systems
Behind-the-meter PV with no export may qualify for simplified G98 processes, with minimal paperwork if the installer confirms compliance .
Battery storage can change requirements — confirm with your installer and DNO before fitting .
The Risks of Proceeding Without DNO Approval
Installing when you should have applied first risks being ordered to disconnect until the DNO approves the connection. That can cause lost generation income, delayed Smart Export Guarantee (SEG) payments, and additional costs for remedial works or retesting.
Unapproved connections also risk safety and compliance issues. If equipment causes network problems, you could face liability for damage or penalties, and insurers or warranty providers might refuse claims if installation didn’t follow DNO rules.
The Step-by-Step DNO Application Process
Step 1: Determining Your DNO and Application Type
- Find your DNO via postcode on the Energy Networks Association (ENA) website.
- Choose the application type: G98 (small systems), G99 (larger/export systems), or bespoke (non-standard equipment).
- Seek pre-application advice for systems near voltage limits or with export control — this clarifies fees and reinforcement needs.
Step 2: Gathering Required Technical Information
Collect and verify these details to avoid delays :
- System specs: PV array size, inverter make/model/export limits, single-line diagram, site address, and connection point.
- Electrical details: Meter type, fuse sizes, earthing arrangements, and photos of the consumer unit/meter.
- Installer credentials: MCS/Competent Person Scheme registration and contact info.
- Large systems: Load flow studies, protection settings, and export control method.
Step 3: Submission and What to Expect Next
- Submit via the DNO’s online portal (e.g., ENA Connect Direct) or email, with fees and required forms .
- Acknowledge receipt within a few working days. Assessment timelines: 10–30 working days for G98; up to 65 days for complex G99 .
- Respond promptly to DNO requests for clarifications. Keep copies of all correspondence and the offer reference number.
Step 4: Post-Approval Installation and Final Notification
- Schedule installation with an MCS-accredited installer, ensuring compliance with DNO conditions.
- Post-installation: Installer submits final notification (including MCS commissioning certificate).
- DNO conducts final checks (remote or on-site) before enabling export.
- Keep all approval and commissioning documents for maintenance, resale, or future upgrades.
Conclusion
A well-prepared DNO application keeps your solar project on track and protects the local grid. By submitting accurate details and following the G98/G99 framework, you minimize delays and unexpected costs .
Work with certified installers to navigate paperwork — their expertise avoids common mistakes and speeds up approval . Expect the DNO to verify export limits, protection settings, and site capacity to prevent network overload .
Organize all correspondence, approval documents, and test results — this simplifies future upgrades (e.g., adding batteries) or resale . Address DNO queries promptly to resolve issues quickly.
Key actions to remember:
- Prepare accurate single-line diagrams and system specs.
- Confirm whether G98 or G99 (or later standards) apply to your setup.
- Use certified installers and keep records for future upgrades.
FAQ: Your DNO Solar Application Questions Answered
1. Who needs to submit a DNO application for solar panels?
You will likely need to engage with your DNO if your solar panel system can export electricity to the grid. A simple rule applies: if your system’s AC inverter output is 3.68 kW (16 Amps) or less per phase, you typically only need to notify your DNO after installation. If it is larger than 3.68 kW per phase, you must apply for approval before installation.
2. Do I need DNO approval BEFORE installing my solar panels?
It depends on your system size. For small systems (≤3.68kW per phase), you can usually install first and then notify your DNO within 28 days using a G98 form. For larger systems (>3.68kW per phase), you must apply for and receive approval before installation begins, following the G99 process.
3. Will my solar installer handle the DNO application for me?
A certified installer will usually manage the application process on your behalf. They gather technical details, submit the correct forms (G98/G99), and liaise with the DNO. However, you remain legally responsible for ensuring the application is made and approval is granted.
4. Are there costs involved in the DNO application process?
Yes, there can be. There may be a fee for processing the application itself. For larger or more complex systems, the DNO might identify a need for local network reinforcement, the cost of which you may be required to pay. Your DNO will provide a connection offer outlining any charges before you commit.
