What is G98 and G99?
UK grid-connection standards that govern how solar and battery systems are connected to the network.
Quick Answer
Every UK solar install must follow G98 or G99 for its grid connection, handled by your MCS-certified installer with the local DNO. Most domestic systems up to 3.68 kW per phase use the simpler G98 notification; larger arrays need G99 approval, which can add time to the project. Export limiting (G100) is sometimes used to gain G98 approval where the DNO would otherwise restrict export.
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
G98 and G99 Explained
G98 and G99 are the UK Engineering Recommendations that set the rules for connecting small-scale generation, like solar and batteries, to the electricity network. G98 covers smaller systems that can be connected on a notify-after basis (typically up to 3.68 kW per phase, around 16A). G99 covers larger systems that need the network operator's approval before connection. A related standard, G100, governs export limitation, which caps how much power a system can send to the grid.
How Does G98 and G99 Work in the UK?
Every UK solar install must follow G98 or G99 for its grid connection, handled by your MCS-certified installer with the local DNO. Most domestic systems up to 3.68 kW per phase use the simpler G98 notification; larger arrays need G99 approval, which can add time to the project. Export limiting (G100) is sometimes used to gain G98 approval where the DNO would otherwise restrict export.
Frequently Asked Questions
What is the difference between G98 and G99?
G98 covers smaller systems (typically up to 3.68 kW per phase) that can be connected by notifying the network operator afterwards. G99 covers larger systems that need the operator's approval before connection. Your installer handles whichever applies with the local DNO.
Do I need G99 approval for my solar panels?
Only if your system is above the G98 threshold (around 3.68 kW per phase, or 16A). Most domestic solar systems fall under G98 and use the simpler notify-after process. Larger arrays need G99 pre-approval, which your MCS-certified installer arranges with the DNO.
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John Rooney is the founder of Solar Info and has been covering the UK solar energy market since 2023. He researches every battery and inverter brand against manufacturer datasheets, MCS and Ofgem data, and feedback from the MCS-certified installers in our directory before publishing.