If you are planning solar panels or a home battery, you may already have heard confusing terms like G98, G99, G100 or DNO approval. The good news is that your installer should handle almost all of this for you, but it helps to understand the basics so you know what is happening and when.
What a DNO is and why they are involved
DNO stands for Distribution Network Operator. This is the company that owns and operates the local electricity cables in your street and the surrounding area.
In Bromley, Chislehurst, West Wickham and Park Langley, the DNO is typically UK Power Networks, although it is always worth confirming for your exact postcode. Your installer can check this for you.
Any time you install equipment that can export electricity back to the grid, such as solar panels or a home battery, your DNO needs to be informed. In some cases they simply need to be notified after the work, and in others they must give approval before the installation goes ahead.
G98 vs G99 explained in plain English
G98 and G99 are national engineering standards that set the rules for connecting generation equipment to the grid. You do not need to read the standards themselves, but it helps to know how they affect your home project.
Very broadly, G98 is used for smaller, straightforward systems that stay within set size limits, while G99 applies to larger or more complex systems, including many battery installations and higher export solar systems.
G98: Notification after installation
Most small domestic solar systems that fit within the standard size limit for a single phase supply will fall under G98. In these cases, your installer can usually fit the system first, then notify the DNO afterwards.
This is often called a "G98 notification" and is a relatively simple process from the homeowner’s perspective. You do not have to apply yourself, and there is usually no delay to the installation date while waiting for DNO approval.
G99: Approval needed before work starts
G99 generally applies when your system exceeds certain export limits, or when there is battery storage or other equipment that can export more power back to the grid. The exact thresholds depend on your property and supply arrangement, so your installer should check them for you.
With G99, the key difference is timing. The DNO usually needs to approve the design before installation. This can add some lead time, but it helps ensure the local network can safely handle your system without causing voltage issues for you or your neighbours.
G98: Smaller, standard systems, DNO notified after installation
G99: Larger or export-capable systems, DNO approval usually needed before work
DNO: Your local grid company, often UK Power Networks in the Bromley area
What makes a job "notification" vs "approval"
The distinction between a simple notification and a full approval mainly comes down to how much power your system can export and whether it fits the standard G98 limits. If it does, your installer can treat it as a G98 notification.
If the proposed system would export more than those limits, or includes certain types of equipment such as larger batteries, then it usually falls under G99. In that case, the installer must send a detailed application to the DNO and wait for their decision before starting work.
A good installer will design your system with these rules in mind and explain whether your project is a G98 notification or G99 approval, along with any timescales involved.
Export limiting and the idea behind G100
Sometimes your property’s local network cannot accept the full export that your ideal system could produce. In these situations, your installer may suggest an export limiting solution.
Export limiting uses a smart device that constantly monitors how much power is flowing to the grid. If your solar panels and battery system start to export more than the agreed limit, the device automatically turns down the output so the limit is never exceeded.
G100 is the engineering standard that covers many of these export limiting arrangements. You do not need to understand the technical detail, just the principle: it lets you install a larger system on paper, while capping what goes back to the grid so your DNO is happy.
This approach can be especially helpful in built-up areas like Bromley and Chislehurst, where the local network may already be quite busy and stricter export limits might apply.
What your installer handles for you
A qualified installer should manage the entire DNO side of things so you are not left wrestling with forms and diagrams. You should still feel free to ask questions, but the heavy lifting should be done for you.
Forms: Completing and submitting G98 or G99 paperwork to the correct DNO
Single line diagrams: Simple electrical diagrams showing how your solar, battery and grid link together
Commissioning tests: Proving the system operates safely and within agreed export limits
Post-install documentation: Sending final test results and certificates back to the DNO
Many installers will also provide you with a straightforward diagram or FAQ sheet that explains your system layout, the main components and what to do if you ever need to contact the DNO or your energy supplier about the installation.
FAQs homeowners often ask about G98 and G99
Will G99 approval delay my project? There can be a wait while the DNO reviews the application, although timescales vary. A proactive installer will submit the paperwork early and keep you updated.
Do I need to contact UK Power Networks myself? In most domestic cases, no. Your installer deals with them and lets you know if anything is needed from you.
Can I upgrade later if export is limited? Often yes, especially if the network is reinforced in future, but it depends on the DNO. Your installer can advise what flexibility you are likely to have.
Planning solar or a battery in Bromley, Chislehurst or nearby?
If you live in Bromley, Chislehurst, West Wickham or Park Langley and are thinking about solar panels, a home battery or both, it helps to have an installer who deals with UK Power Networks paperwork all the time.
At J. Durka Electrical Services, we design your system, check the G98 or G99 requirements, and manage the full DNO process from first enquiry to final sign-off. You get clear explanations, simple diagrams and a dedicated contact if you ever have questions.
To learn more about battery options, visit our battery storage services page.
If you are planning solar or a battery installation in Bromley, Chislehurst, West Wickham or Park Langley, book a survey with J. Durka Electrical Services and we will manage the DNO process for you from start to finish. To get started, call us on 07977479071.
