Guide
G98 vs G99: which one do you need?
G98 and G99 are the ENA engineering recommendations for connecting generation and storage, such as solar PV and batteries, to the GB distribution network. Which one applies mostly comes down to size and whether the kit is fully type tested.
- G98: fully type-tested, up to 16A per phase in total
- G98: tell the DNO within 28 days of commissioning
- G99: bigger systems, or kit that isn't fully type tested
- G99: apply to the DNO and wait before you install
Doing your own system? The Homeowner DNO Pack (£100 incl VAT, Great Britain only) fills in a G98 or G99 pack for you to send. It covers Type A systems only (under 17kW single phase and under 50kW), and DNO fees aren't included.
Homeowner DNO PackThe short version
G98: connect and notify
For fully type-tested micro-generators where the total on the installation is no more than 16A per phase. That's about 3.68kW on a single-phase supply or 11.04kW on three-phase. You tell the DNO before commissioning or within 28 days after it.
G99: apply before you connect
For anything over 16A per phase in total, or kit that isn't fully type tested under G98. You apply to the DNO first and wait for their answer before installing. The DNO may ask for changes or network work.
G100: export limitation
If the system can generate more than the DNO will accept on export, an export limitation scheme can cap what goes back to the grid. That needs the G100 information as well as the G98 or G99 application.
Things that catch people out
- The 16A per phase limit is the total on the installation, so a battery inverter alongside a solar inverter counts towards it
- Adding to an existing system can push the total over 16A per phase, which takes the whole thing into G99
- Several G98 installs in the same area within 28 days are treated differently: the normal notify-after route doesn't apply, so check with the DNO first
- For connect and notify through ENA Connect Direct, ENA asks for a clear photo of the cut-out
- Fast track G99 routes exist for some small systems. Check what your DNO offers
- The DNO decides whether to accept a connection, on any route
This guide is a summary, not the standard. Always check the current ENA EREC G98, G99 and G100 documents and your DNO's guidance for the job in front of you.
How CircuitHQ helps
Picks the forms
CircuitHQ picks the right forms from the kit and capacity: G98, G99 fast track or full application, the G99 post-commissioning forms and the G100 Appendix B form.
Fills them from the job
The customer, site, devices and commissioning details come from the job and your device library, and it flags anything missing.
Submits eligible applications
For G98 and G99 solar and battery applications where every device is on the ENA device register, and EV chargers, under 17kW per phase, you review the application and press Submit to send it to ENA Connect Direct from the app.
Flags big systems
Systems of 17kW or more single phase, or 50kW or more, are flagged for you to talk to the DNO about.
Try it for yourself
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Questions
What is the difference between G98 and G99?+
G98 covers fully type-tested micro-generators up to 16A per phase in total, and you notify the DNO within 28 days of commissioning. G99 covers anything bigger, or kit that isn't fully type tested, and you apply to the DNO before installing.
What size system needs a G99 application?+
Anything over 16A per phase in total across the installation, which is about 3.68kW single phase or 11.04kW three phase. That total includes batteries and any existing generation on the same installation.
How long do I have to send a G98 notification?+
G98 says the DNO must be made aware before commissioning or no later than 28 days after it, counting the day of commissioning.
Do batteries need G98 or G99?+
Battery storage that can export counts as generation for G98 and G99, so it's added to the total on the installation. A solar and battery system that's over 16A per phase in total needs G99.
What is G100?+
G100 is the ENA recommendation for export limitation schemes, which cap how much a site exports to the grid. It's used where the system could export more than the DNO will accept.
Can CircuitHQ send my G98 or G99?+
For G98 and G99 solar and battery applications where every device is on the ENA device register, and EV chargers, under 17kW per phase, yes: you review the application and press Submit to send it to ENA Connect Direct. G100 or export-limited setups, and changes to existing applications, get prepared forms and a draft email that you check and send yourself.
More from CircuitHQ
Sources: ENA EREC G98 Issue 2 (2025) and the ENA G99 Type A summary guide, checked 30 Oct 2026. G98, G99, G100 and ENA Connect Direct are Energy Networks Association documents and services. CircuitHQ isn't endorsed by the IET, NICEIC, NAPIT, MCS, the ENA or any DNO.