G98 vs G99 – What's the Difference?
If you're considering installing solar panels or battery storage, you've probably come across the terms G98 and G99. These are the engineering recommendations that determine how your renewable energy system connects to the UK's electricity network.
Understanding the difference between G98 and G99 is important because it affects the size of system you can install, whether permission is required before installation, and how your Distribution Network Operator (DNO) manages your connection.
This guide explains G98 and G99 in simple terms, helping homeowners, businesses and developers understand which process applies to their installation.
What is G98?
G98 is the simplified connection process for smaller microgeneration systems connected to the public electricity network.
For most domestic properties, a G98 installation allows an inverter with a maximum export capacity of 3.68kW per phase (16 Amps).
Under G98, installers can normally:
- Install the system first
- Commission the equipment
- Notify the DNO after installation
This is commonly known as the Connect and Notify process.
Typical G98 systems include:
- Domestic solar PV
- Hybrid solar and battery systems
- Battery-only installations
- Small renewable generation systems
Providing the inverter's
export
does not exceed the G98 limits, the process is generally straightforward.
What is G99?
G99 applies to renewable energy systems capable of exporting more than 3.68kW per phase, or installations that fall outside the scope of G98.
Unlike G98, approval is generally required before installation unless a recognised fast-track or limited-export process is being used.
A G99 application enables
larger systems, including:
- Larger domestic solar installations
- Commercial solar PV systems
- Larger battery storage systems
- Three-phase renewable installations
Your DNO assesses whether the local electricity network has sufficient capacity before granting permission.
G98 vs G99 – The Main Differences
| Feature | G98 | G99 |
|---|---|---|
| Maximum Export | Up to 3.68kW per phase | Above 3.68kW per phase |
| DNO approval | Usually after installation | Usually before installation |
| Typical property | Domestic | Domestic & Commercial |
| Installation | Connect & Notify | Application Required |
| Larger batteries | Sometimes | Yes |
| Larger inverters | No | Yes |
Can a Larger System Still Export 3.68kW?
Yes.
Modern hybrid inverters often include G100 export limitation, allowing
larger systems to be installed while electronically limiting the export to the agreed level.
This means a homeowner may benefit from:
- Larger solar arrays
- Larger battery storage
- Greater self-consumption
- Increased battery charging performance
while ensuring no more than the permitted export reaches the electricity network.
Which One Do I Need?
Every property is different.
Factors include:
- Your annual electricity consumption
- Number of solar panels
- Inverter size
- Battery capacity
- Existing electrical supply
- Whether the property has single or three-phase electricity
- Your local
DNO
requirements
A professional design should always consider both the customer's energy needs and the available network capacity before selecting the most appropriate connection route.
How Zero Carbon Can Help
At Zero Carbon, every renewable energy system is individually designed to maximise performance while remaining fully compliant with the relevant engineering recommendations.
Our engineering-led approach considers:
- Solar generation
- Battery storage
- Future expansion
- Electric vehicle charging
- Heat pumps
- Export limitation
- DNO applications
- MCS compliance
Whether your project falls under G98 or requires a G99 application, we manage the technical process from system design through to network notification and approval
Frequently Asked Questions
Is G99 better than G98?
Not necessarily. The correct route depends on your system design and export capability.
Can I install a larger inverter on G98?
Only where export limitation and applicable engineering requirements allow it. Your installer should advise on the most appropriate connection method.
Does G99 mean expensive grid upgrades?
No. Many G99 applications are approved without reinforcement, although each property is assessed individually by the DNO.
Can batteries affect whether I need G99?
Yes. The inverter's export capability and overall system design can influence whether a G98 or G99 connection process is appropriate.
