DNO Application for Solar Panels UK: G98 vs G99 Explained (2026)

If you have been quoted for solar panels, you have probably seen the letters "DNO" on your paperwork — usually next to "G98" or "G99". These are the rules that decide whether your installation can go ahead straight away, or whether it needs pre-approval from the company that runs your local electricity network. For most UK homes the process is invisible. For larger systems, it is the single biggest thing that can delay your install.

This guide covers what a DNO is, when you need G98 vs G99, how long it takes, what it costs, and who your DNO is depending on where you live.

What Is a DNO? (Solar Grid Connection Explained)

A Distribution Network Operator (DNO) is the company that owns and maintains the physical electricity network in your local area — the cables, substations and transformers that carry power from the national grid to individual properties.

A DNO is not the same as your energy supplier. You have no choice in who your DNO is — it is determined by your postcode.

Why Does the DNO Care About Your Solar Panels?

The UK electricity network was built on the assumption that electricity flows one way: from power stations, through the grid, into homes. Solar panels break that assumption. On a sunny day they generate more than the household uses, and the surplus flows back into the local network.

If too many properties in the same area export at the same time, it can cause voltage to rise above safe limits, damaging equipment on the network and in nearby homes. The DNO needs to know about every generator connected to their network so they can:

• Model how much generation is expected on each substation
• Identify where network upgrades are needed
• Set export limits if the local network is already near capacity
• Register your system for the Smart Export Guarantee (see our SEG guide)

G98 vs G99: Which One Applies to You?

The split between G98 (simple notification) and G99 (pre-approval) is based on how much electricity your inverter can push back to the grid — not how many solar panels you have.

Single-phase (most UK homes)

Roughly 95% of UK homes are single-phase. A 4kW solar system using a 3.68kW inverter is comfortably inside the G98 limit. In practice, many installers size the inverter slightly below the panel total (known as "inverter clipping") precisely to keep the system within G98 and avoid the G99 waiting period.

Three-phase (most businesses, some larger homes)

Three-phase properties have a higher G98 threshold of 11.04kW total inverter capacity. Commercial installations frequently exceed this and fall under G99.

Battery systems — an important exception

Batteries only count toward the G98/G99 limit if they are configured to export to the grid. A battery set to "no export" mode may not push the system over the threshold, even if the inverter is rated above 3.68kW. Your installer confirms this during system design — see our solar battery cost guide for how this affects battery choice.

The G98/G99 Application Process (Step by Step)

G98 (simple notification)

1. Installer completes the installation
2. Installer submits the G98 form to your DNO within 28 days, including MCS certificate and inverter details
3. DNO updates their network records — no action needed from you
4. You register for SEG with your chosen energy supplier (see our best Octopus tariffs guide)

G99 (pre-approval)

1. Installer submits G99 application to your DNO before any equipment is installed
2. DNO assesses local network capacity — this is the part that can take up to 45 working days
3. DNO responds with one of: approval as designed, approval with export limits, request for network upgrades, or (rarely) refusal
4. Installer negotiates any changes — for example, reducing inverter size or accepting an export cap
5. Installation proceeds once approval is in place
6. Installer notifies the DNO when commissioned

Typical G99 Outcomes

• Approved as designed — most common for domestic systems just over the G98 threshold (e.g. 4kW inverter on a single-phase home)
• Export limit — the DNO approves the system but caps how much it can send to the grid (e.g. 3.68kW export from a 5kW inverter). You still generate and use the full amount yourself; you just cannot export the surplus. Often modest impact on earnings.
• Network upgrade required — less common. Usually applies to rural areas, older network infrastructure, or where many local systems are already installed. May involve homeowner contribution to upgrade costs.
• Refusal — rare for domestic installations. More common for commercial and battery-heavy systems in congested areas.

The Nine UK DNO Regions

The UK is divided into nine licensed distribution areas, each run by a different DNO. Your postcode determines which one serves you.

You can confirm your DNO by entering your postcode on the Energy Networks Association website, or by checking a recent electricity bill — your Meter Point Administration Number (MPAN) encodes the area.

Common Questions About the Solar Grid Application

"Will the DNO application delay my install?"

For a standard 4kW domestic system on single-phase supply, no — you are in G98 territory, and the notification happens after the job is done. If your system is larger, or you are adding a large battery with export capability, a G99 delay of 4–9 weeks is possible.

"Is the DNO fee hidden in my quote?"

Reputable MCS-certified installers include DNO handling in their standard quote. Ask explicitly: "Does this price cover the G98/G99 application?" For G99 applications that trigger network upgrade charges, a good installer will flag the risk upfront rather than pass the cost to you mid-project.

"Can I submit the DNO application myself?"

Technically yes, but it is not recommended. The application needs technical data about the inverter, the protection settings, and the installation method — all of which an MCS-certified installer produces as part of the commissioning process. DIY solar in the UK is legally possible but complicates DNO approval, SEG registration and building regulations.

"What if I add a battery later?"

Adding a battery to an existing solar system usually requires a new DNO notification, even if the original solar install was G98. If the battery adds export capability that pushes the total above 3.68kW, it may require a G99 application. Your battery installer handles this.

What This Means for Choosing an Installer

Most homeowners never interact with their DNO directly — the installer does all the paperwork. But you should still verify:

• The installer is MCS-certified (required for SEG registration and 0% VAT)
• DNO applications are included in the quoted price
• The installer has experience in your region — DNO processes vary slightly between operators
• Any system sized above 3.68kW inverter has a clear plan for handling G99 timelines

Next Step

Getting three MCS-certified quotes is the best way to benchmark both price and DNO handling. Use our installer comparison tool to find accredited installers in your region — all listed installers handle DNO applications as standard.