Posted:
- Guide
If you're getting solar panels installed, you'll hear the terms G98 and G99 at some point. Before any solar system connects to the electricity grid, the local network operator needs to know about it.
This guide explains what a DNO application is, when you need one, what the difference is between G98 and G99, and how long the whole process takes.
What is a DNO application for solar panels?
A DNO is a Distribution Network Operator. It's the company responsible for the electricity cables and infrastructure in your area, not your energy supplier. There are six main DNOs in the UK, each covering a different region.
When you install solar panels, your system connects to the electricity grid. The DNO needs to approve that connection to make sure your system won't cause problems for the local network, such as voltage fluctuations or overloading.
The DNO application is the formal process for getting that approval. In most cases your installer handles it entirely. You don't need to contact your DNO directly.
Do I need a DNO application for solar panels?
Yes, in almost all cases. The question is whether you need a full application or a simpler notification. That depends on the size of your system.
| System type: | Size: | Process required: | Who submits it: | Timescale: |
|---|---|---|---|---|
| Most domestic solar | Under 3.68kW | G98 notification | Your installer | 10 to 15 working days |
| Larger domestic or small commercial | 3.68kW to 16kW | G98 application | Your installer | 10 to 15 working days |
| Commercial or large domestic | Over 16kW | G99 application | Your installer | Up to 60 working days |
System size thresholds are based on single phase connections. Three phase connections have different thresholds. OVO will confirm which applies to your property during the survey.
What is the difference between G98 and G99?
G98 and G99 are two sets of technical standards published by the Energy Networks Association. They set out the requirements for connecting generation equipment to the grid safely.
What is a G98 application?
G98 covers solar systems up to 16kW. Most domestic installations fall under G98. The process is simpler and faster because smaller systems have less potential to affect grid stability. For the majority of home solar installations, your installer submits a G98 notification before work begins. Approval typically comes within 10 to 15 working days.
What is a G99 application?
G99 covers larger solar systems over 16kW. These are typically commercial installations or very large domestic systems. G99 requires more detailed technical assessment because larger systems can have a bigger impact on the local network. The process takes longer, up to 60 working days, and involves more documentation.
G98 vs G99: a quick comparison
| G98 | G99 | |
|---|---|---|
| System size | Up to 16kW | Over 16kW |
| Typical use | Most home solar panels | Commercial solar, large systems |
| Application type | Notification or simple application | Full technical application |
| Approval time | 10 to 15 working days | Up to 60 working days |
| Cost | Usually included in installation | DNO fee may apply, OVO will advise |
| Who submits | Your installer | Your installer |
| Impact on your installation timeline | Minimal | Can delay start date, plan ahead |
How long does a DNO application take?
This is one of the most common questions from homeowners planning a solar installation. Here's what to expect.
• G98 notification: 10 to 15 working days. This is the most common route for domestic solar. OVO submits the notification before installation begins, so by the time your panels are fitted, approval is usually already in place.
• G99 application: up to 60 working days. This applies to systems over 16kW. For commercial projects, OVO submits the G99 application as soon as your system design is agreed, so the clock starts as early as possible.
Timescales can vary. DNOs in areas with high solar adoption or grid constraints sometimes take longer to process applications. OVO monitors the status of your application and chases the DNO if there are delays. You won't need to follow this up yourself.
How long does DNO approval take in each region?
Each DNO covers a different part of the UK. Processing times can vary by region depending on the volume of applications and local grid conditions.
| DNO | Region covered | Typical G98 timescale | Typical G99 timescale |
|---|---|---|---|
| SP Energy Networks | Scotland and North West England | 10 to 15 working days | Up to 60 working days |
| Scottish and Southern Electricity Networks | Scotland, South East and South England | 10 to 15 working days | Up to 60 working days |
| Northern Powergrid | North East England and Yorkshire | 10 to 15 working days | Up to 60 working days |
| Electricity North West | North West England | 10 to 15 working days | Up to 60 working days |
| National Grid Electricity Distribution | Midlands, South West, South Wales | 10 to 15 working days | Up to 60 working days |
| UK Power Networks | South East, East and London | 10 to 15 working days | Up to 60 working days |
Timescales are typical and can vary. OVO will advise on the current processing time for your specific DNO at the time of your installation.
What information does the DNO need?
• Inverter make, model, and power output
• Total system generation capacity in kW
• Single phase or three phase connection details
• Grid connection point and location
• Full electrical layout and wiring diagram
• MCS installer certification details
Your installer provides all of this as part of the application.
What happens if you install solar without a DNO application?
Installing solar without the required DNO approval is a serious problem. Approvasl is not just a technicality.
• Your system may not be legally connected to the grid, which means you can't export electricity or receive SEG payments
• Your home insurance may be invalidated if the installation isn't compliant
• Selling your home becomes complicated, as buyers' solicitors routinely ask for evidence of DNO approval
• The DNO can require you to disconnect the system at your own cost
OVO handles the DNO application as a standard part of every installation. You won't be in a position where approval hasn't been obtained.
Can the DNO reject a solar application?
Yes, though it's uncommon for straightforward domestic systems. The most likely reasons for rejection are grid capacity constraints in your local area or a technical issue with the system specification.
If a G99 application is rejected, OVO will work with you to understand the reason and explore whether a system redesign or phased installation would resolve it. For G98 applications, rejection is rare.
Does OVO handle the DNO application?
Yes. OVO submits and manages the entire DNO process on your behalf. This includes choosing the right application type for your system, submitting all required documentation, monitoring the application status, and managing any queries from the DNO.
You don't need to contact your DNO at any point. OVO will let you know when approval has been received and confirm the installation timeline.
Frequently asked questions
Do I need to contact my DNO before getting solar panels?
No. Your installer contacts the DNO on your behalf. OVO handles the entire DNO application process as part of your installation. You don't need to do anything.
What is the G98 form for solar panels?
The G98 form is the official application document used to notify a DNO that a solar system under 16kW is being connected to the grid. Your installer completes and submits it. OVO uses the standard ENA G98 form for all relevant installations.
How long does DNO approval take for a typical home solar installation?
For most domestic systems under 3.68kW, the G98 notification process takes 10 to 15 working days. OVO submits this before installation begins, so approval is usually in place by the time your panels are fitted.
What is the difference between DNO notification and DNO application?
A G98 notification is a simpler process for smaller systems where the DNO is informed rather than asked for detailed approval. A G99 application is a full technical submission for larger systems that requires more detailed assessment and takes longer. Both are referred to loosely as DNO applications.
Does the DNO application affect my installation date?
For G98 systems, the impact is minimal as OVO submits the notification early and approval usually comes quickly. For G99 systems, the application needs to be submitted before installation can begin, so the 60 working day window is factored into your project timeline from the start.
Is a DNO application needed for a solar battery without panels?
It depends on the size and setup of the battery. A standalone battery that doesn't export to the grid may not require a DNO application. If the battery is installed alongside solar panels, the combined system capacity determines which application applies. OVO will confirm what's required during your survey.
Get a free solar quote from OVO
OVO handles the DNO application as part of every solar installation, so you don't need to worry about the process. To find out what a solar system would cost and save for your home, get a free survey and quote from OVO's local team.