If you're considering solar panels, home battery storage or a combination of the two, you may come across the terms G98, G99 and DNO approval. They sound technical, but they're an important part of connecting an electricity-generating system to the grid.

The good news is that you shouldn't need to navigate the process alone. At Renewable Energy Service, the DNO application is taken care of as part of our installation process, giving you one less thing to worry about.

What are G98 and G99?

G98 and G99 are connection requirements relating to generating equipment that operates in parallel with the electricity distribution network.

This is relevant when installing technology such as home solar panels and certain home battery storage systems.

The requirements that apply will depend on factors such as your proposed system, its output, the equipment being installed and your electricity connection.

In simple terms:

• G98 generally applies to smaller generation systems within the relevant per-phase limits.
• G99 applies where an installation falls outside the G98 requirements and normally requires approval from the Distribution Network Operator before connection.

What is a DNO?

Your Distribution Network Operator, or DNO, is responsible for the electricity distribution network in your area.

When solar panels or battery storage are being connected to your property, your DNO may therefore need information about the proposed system and how it will interact with the local electricity network.

This shouldn't be confused with your electricity supplier. Your supplier is the company you buy your electricity from, whereas the DNO manages the local network that delivers electricity to homes and businesses.

What is the difference between G98 and G99?

The key distinction is the type and scale of the installation being connected.

What is G98?

G98 covers smaller generation installations that meet the relevant requirements, including the applicable 16A per-phase threshold.

Many smaller domestic renewable energy installations can fall within G98 requirements, depending on the system design.

What is G99?

If the proposed installation falls outside the requirements for G98, the system may instead need to follow the G99 connection process.

This is particularly important because a G99 installation can require the DNO to assess the proposed connection before the system is installed and connected.

Your installer should identify which process applies as part of designing your system rather than leaving you to work it out yourself.

Do I need a G98 or G99 application for solar panels?

If you're installing solar panels at home, the appropriate grid connection requirements need to be considered as part of your system design.

Which route applies isn't simply a matter of counting your solar panels. The specification and configuration of the equipment being connected to the grid also matters.

This is why the grid connection should be considered when your solar system is being designed, rather than treated as an afterthought once the panels have been fitted.

Do home batteries need DNO approval?

Battery storage can also have implications for your property's grid connection.

If you are adding a battery to an existing solar installation or installing a standalone home battery, the way the system connects to and interacts with the grid needs to be taken into account.

That is becoming increasingly relevant as homeowners use batteries not only to store surplus solar generation but also to charge from the grid when electricity is cheaper.

If you're interested in the latter, our guide to battery arbitrage explains how a home battery can be used to shift electricity consumption from more expensive periods to cheaper periods.

Can a DNO limit my solar or battery system?

Yes. The DNO may place conditions on a proposed connection depending on the property, the system and the capacity of the local network.

For example, a connection may be subject to an export limitation, which restricts how much electricity the system can export onto the grid.

Depending on the proposed installation, additional technical information or changes to the system design may also be required before a connection can proceed.

Importantly, a grid restriction doesn't necessarily mean you cannot have solar panels or battery storage. It can sometimes mean designing or configuring the system differently so that it can operate within the permitted limits.

What is an export limitation?

An export limitation restricts the amount of electricity your system can send back to the electricity network.

This can be relevant where you have a larger solar array or battery system but the local electrical network cannot accommodate the system's potential maximum export.

Rather than necessarily reducing the amount of generation or battery capacity installed, an appropriate system may be configured so that its export to the grid remains within the agreed limit.

This makes it important to consider your DNO requirements alongside the design of your solar and battery system.

Should I apply to the DNO myself?

For most homeowners, there should be no need to become an expert in G98, G99 or DNO applications.

Your installer should understand the proposed equipment, determine the appropriate connection process and handle the relevant DNO requirements as part of the project.

Renewable Energy Service includes the DNO application and MCS certification within its domestic solar installations, alongside the electrical and roofing components, warranties and handover documentation.

The DNO application is also included with our Battery Advantage installations.

Why should DNO requirements be considered before installation?

Understanding the grid connection requirements early means any limitations can be incorporated into the design of your system.

That's particularly important if you're considering a larger solar array, substantial battery capacity or a system designed around greater energy independence.

At Renewable Energy Service, we believe you should understand what you're buying before your installation goes ahead. If the DNO places a relevant restriction on the proposed system, we'll explain what it means and how it affects the system being designed for your home.

G98 and G99 without the jargon

If all of this still feels technical, the important point is simple:

G98 and G99 are part of making sure that solar panels and battery storage are connected to the electricity network appropriately.

You don't need to become a grid-connection expert to install renewable technology at your home. You need an installer that understands the requirements and takes care of the process for you.