G98 vs G99 solar: DNO connection guide
Do you need DNO approval for solar panels? Understand G98, G99, the 3.68kW-per-phase threshold and what your installer should handle.
Key takeaways
- For a normal grid-connected installation, the DNO needs either a G98 notification or a G99 application.
- G98 covers compliant generation up to 16A per phase: 3.68kW on a single-phase supply.
- Your installer normally handles the process, but you should receive the relevant evidence in the handover pack.
Do I need DNO approval for solar panels?
If a solar or battery system will operate in parallel with the electricity grid, the local Distribution Network Operator needs to know about it. The route is usually a G98 notification for a smaller compliant installation or a G99 application when the grid-facing capacity is higher or the G98 conditions are not met.
Your DNO owns and manages the local network; it is not usually the company that sends your electricity bill. For a domestic installation, the installer normally completes the paperwork, but the route can affect system design and timing.
G98: install, then notify
The Energy Networks Association Distributed Generation Guide describes G98 for single premises as generation with combined registered capacity no higher than 16A per phase. That works out as 3.68kW on a single-phase supply or 11.04kW on a three-phase supply.
A compliant G98 system can normally be installed first and notified to the DNO shortly afterwards by the installer. A 4kWp panel array can still use a 3.68kW inverter: panel capacity and maximum AC output are not the same figure.
G99: apply before connection
National Grid's guidance says G99 applies where generation or storage is rated above 16A, which is 3.68kW per phase, or where the system doesn't meet the current G98 requirements.
Unlike the usual G98 route, G99 requires the DNO to assess the proposal before the equipment is connected. G99 is not a warning sign: the DNO may approve the design as submitted, ask for an export limit or specify other connection conditions.
What the installer should handle
Before installation, the installer should identify the DNO route from the inverter arrangement, phase supply and any battery. For G99, they should submit the application early enough for the decision to inform the final design. For G98, they should make the required post-install notification.
At handover, ask for the notification or approval evidence and details of any export limit. You may need clear connection paperwork when arranging export payments, changing equipment or selling the property.
Questions for your quote
Ask your installer what inverter capacity they're proposing, whether the system is G98 or G99, and whether any G100 export limitation is being used. If a battery is included, ask whether the combined inverter arrangement changes the DNO route.
Don't confuse kW and kWh. kW is power at a point in time. kWh is energy over time. DNO limits are usually about power capacity, while your annual savings are based on kWh generated, used and exported.
- What is the inverter AC output?
- Is the system G98, G99 or G99 fast track?
- Is export limited, and if so to what kW?
- Will the DNO evidence be included in the handover pack?
Put the connection rules into context
Sources checked
- Energy Networks Association Distributed Generation GuideG98 and G99 connection process guidance.
- National Grid G99 connection proceduresPlain guidance on when G99 applies.