If you’re considering solar panels or battery storage for your home, you may have heard about something called a DNO application. It can sound technical, but it’s a standard and essential part of connecting your system safely to the grid.
In this guide, SolarTherm UK explains exactly what a DNO is, when an application is required and how the process works for homeowners across the South East and East Anglia.
What is a DNO?
A Distribution Network Operator (DNO) is the company responsible for maintaining the electricity infrastructure in your local area. This includes the cables, substations and network that deliver power to your home.
When you install solar panels or a battery system, your property may begin exporting electricity back to the grid. Your DNO must assess whether the local network can safely handle this additional energy.
What Does the DNO Assess?
- Network capacity – can your local grid manage exported electricity without overloading?
- System safety – does your installation meet UK engineering standards?
- Power quality – will your system affect voltage levels or neighbouring properties?
This step ensures your system operates efficiently without causing disruption to the wider network.
What is a DNO Application?
A DNO application is the formal process of notifying or requesting permission to connect your solar PV or battery storage system to the electricity grid.
Depending on your system size, the process may involve a post installation notification (G98) or pre-installation approval (G99 and G100).
G98 vs G99 vs G100: Understanding the Rules
G98 – For Smaller Residential Systems
If your solar PV system is up to 3.68kW per phase, it typically falls under G98. Installation can proceed immediately, and your installer notifies your DNO within 28 days of installation. No prior approval is required – this is usually called a fit and notify installation. This is the most common route for standard domestic solar installations.
G99 – For Larger Systems or Battery Installations
If your system exceeds 3.68kW per phase or includes battery storage, it usually requires a G99 application. Approval must be granted before installation. Assessment can take several weeks and may involve wider network capacity checks. This applies to larger homes or systems designed for higher energy output.
G100 – Export Limitation Systems
In some cases, your local network may not be able to accept the full export from your system. A G100 application allows for:
- Installation of an export limitation device
- Controlled export to the grid
- Compliance with DNO requirements without any costly upgrades to the network
What is a DNO Approval Letter?
Once your system has been approved or registered, your DNO will issue a confirmation document – often referred to as a DNO letter. This document confirms your system is compliant with UK regulations. It also authorises your connection to the grid and approves export arrangements.
You’ll need your DNO approval letter to register for the Smart Export Guarantee (SEG) – which pays you for any energy your export to the grid. Your letter will also be needed if you were to sell your property in the future or if you switch energy suppliers.
How Long Does the Process Take?
- G98 systems – no delay, install first, notify after
- G99 applications – typically 2-6 weeks
- G100 applications – can take longer depending on the complexity of the install
Who is the DNO in the South East and East Anglia
For most homeowners in our service area, your DNO is UK Power Networks. They manage electricity infrastructure across the South East, East Anglia and London.
Do You Need to Handle the Application Yourself?
No – your shouldn’t have to. When you work with a qualified installer like SolarTherm UK, we handle the entire DNO process on your behalf, including:
- System classification (G98, G99, G100)
- Application preparation and submission
- Liaising directly with the DNO
- Ensuring full compliance with UK standards
Why Choose SolarTherm UK?
At SolarTherm UK, we specialise in residential solar installations across the South East and East Anglia. Our team works with MCS certified systems and follows the latest engineering standards to ensure every installation is safe, efficient and future proof.
What sets us apart from the rest:
- Experienced solar specialists with local network knowledge
- Full project management, including DNO applications
- High quality system design tailored to UK homes
- Transparent advice with no pressure sales approach
We don’t just install solar – we ensure your system performs optimally within your local grid constraints.
Thinking About Solar or Battery Storage?
If you’re exploring solar panels or battery storage, getting the DNO process right is essential – but it doesn’t need to be complicated.
SolarTherm UK manages everything from system design to grid approval, giving you a smooth compliant installation from start to finish.
Contact SolarTherm UK today for a free, no obligation quote and design, tailored to your property, usage and future energy needs. No hard sell, just honest, expert advice – and the time you need to make an informed decision.
Your home. Your energy. Your future.
FAQs
Do all solar panel systems need DNO approval?
Not always. Smaller systems (under 3.68kW per phase) typically fall under G98 and only require notification after installation.
Do batteries always require a DNO application?
Yes, in most cases battery systems fall under G99 and need approval before installation.
What happens if my system is too large for the grid?
Your installer may recommend an export limitation system under G100, allowing you to install solar without overloading the grid.
Can I apply to the DNO myself?
Technically yes, but it’s strongly recommended your installer handles it to avoid delays or errors.
Will a DNO application delay my installation?
Only for larger systems. Most standard residential installs proceed without delays under G98.
