M&E Contrax Resources

DNO Approval

Resource Highlights:

DNO approval is how the local grid operator confirms your system can connect safely and what export limits apply.

Most domestic solar installs fall under G98 or G99, depending on system size and connection type.

A good installer manages the DNO process for you and explains it clearly.

What it means for solar PV, battery storage, and your installation

If you’re researching solar panels, battery storage, or commercial renewables, you’ll often hear the term DNO approval.

DNO stands for Distribution Network Operator. They manage the local electricity network in your area and are responsible for making sure new generation equipment, like solar PV and batteries, can connect safely without causing issues on the grid.

In simple terms, DNO approval is the process of confirming how your solar system can connect and how much electricity it can export.

This guide explains what DNO approval is, when it is required, and what to expect during the process.

What is a DNO?

A Distribution Network Operator (DNO) maintains the cables, substations and equipment that supply electricity to properties in a local region.

When you install solar PV or battery storage, you are adding generation equipment to that network. The DNO needs to ensure:

the connection is safe

the network can handle the extra generation

voltage and protection settings remain within limits

export does not cause technical problems locally

What is DNO approval?

DNO approval usually refers to one of two things:

Notification

For smaller systems that meet certain criteria, the installer can install and then notify the DNO afterwards.

Application and permission

For larger systems or certain configurations, an application must be submitted and approved before installation and commissioning.

Your installer should confirm which route applies to your system and handle the paperwork.

When do you need DNO approval?

You may need DNO approval when installing:

solar PV

battery storage

hybrid inverters

larger domestic systems

commercial solar PV systems

systems with higher export capability

certain three phase properties

systems where export is likely to exceed standard limits

Many homeowners never have to think about it because their installer manages it as part of the installation process.

G98 vs G99, the simple explanation

You will often see DNO approval discussed alongside G98 and G99. These are the main technical routes used for connecting small scale generation to the grid.

G98

G98 is typically for smaller microgeneration connections. In many cases, systems installed under G98 are notified to the DNO after installation, assuming they meet the relevant limits and requirements.

G99

G99 is used for larger systems or situations where permission is needed before installation. It generally involves an application and approval process, and it is common for commercial installations.

Your installer will know which route applies and will manage the correct process.

Export limits, what they mean and why they happen

Export limits are one of the most common outcomes of DNO approval.

An export limit means:

your system may generate more electricity than you can export to the grid

surplus export may be capped at a set level

you can still use electricity on site as normal

Export limits are used to protect the local network. They can be affected by:

the capacity of local cables and substations

the number of solar systems already connected nearby

whether the local network is constrained

Important point

Export limits do not automatically reduce the value of solar, especially if your property can use a good amount of power on site. Many systems are designed to maximise self consumption first, which is often where the biggest savings come from.

How the DNO process works

Installer checks your system design

Your installer reviews your proposed system size, inverter type, battery plans, and whether the property is single phase or three phase.

Application or notification route is chosen

If the system fits within standard microgeneration limits, it may be installed and then notified.

If it requires permission, an application is submitted before work begins.

DNO reviews and confirms outcome

The DNO may:

approve the connection as proposed

approve with an export limit

request changes to equipment or protection settings

in some cases, advise network upgrades are needed

Installation and commissioning

Once the correct route is followed, the system is installed and commissioned, and the final paperwork is completed.

How long does DNO approval take?

Timescales vary depending on:

whether it is G98 notification or a G99 application

local DNO workload

whether export limits or network upgrades are involved

whether the system is domestic or commercial

A good installer should set expectations early and keep you updated.

DNO approval for battery storage

Battery storage can also involve DNO requirements, especially if:

the battery can export to the grid

a hybrid inverter is used

the system is larger or three phase

you are installing battery storage without solar but still exporting

Battery systems can often be configured to:

prioritise self consumption

reduce export

operate within DNO limits where required

This is why design and commissioning matter.

DNO approval for commercial solar PV

Commercial solar almost always includes a DNO review, because:

systems are typically larger

sites may have three phase supplies

metering and distribution can be more complex

For commercial systems, DNO outcomes can shape:

how the system is sized

whether export is capped

whether batteries are recommended

whether the project should be phased

Common mistakes to avoid

Assuming DNO approval is optional

It is part of safe and compliant grid connection for many systems.

Oversizing a system without checking export constraints

A larger system is not always better if the grid cannot accept export.

Not planning batteries properly

Battery storage can help increase self consumption and reduce export, but it must be designed and set up correctly.

Comparing quotes without checking DNO scope

Some quotes include full DNO management, others do not. Always confirm what is included.

Simple overview

If you want the simplest approach, follow this order:

Decide whether your system is domestic or commercial

Confirm whether you have a single phase or three phase supply

Design the system around on site usage first

Your installer submits the correct DNO route, G98 or G99

Confirm any export limits or requirements

Install, commission, and receive documentation for handover

This avoids delays and ensures your system is designed properly from the start.

Frequently Asked Questions

Most systems require either DNO notification or approval, but the route depends on system size and setup. Your installer should manage this.

G98 is typically used for smaller microgeneration systems, often with post installation notification. G99 is generally for larger systems that need permission before installation.

Not necessarily. Many systems deliver most value through self consumption, using power on site. Export limits mainly affect how much surplus can be exported.

They can. Batteries can store surplus energy for later use and reduce export, depending on how the system is configured.