G98, G99 and G100 describe different parts of connecting solar panels, batteries and other generation to the electricity network. G98 covers qualifying small generators; G99 covers generation outside that route; G100 covers controls that keep power flows within an agreed limit.
This guide explains the differences. For paperwork, costs and timescales, see our DNO application guide.
G98, G99 and G100 compared
| Standard | Main purpose | Practical question |
|---|---|---|
| G98 | A connection route for qualifying fully type-tested microgeneration up to 16A per phase. | Does the complete installation qualify for the simpler notification route? |
| G99 | Connection requirements for generation outside G98. | What approval, protection and commissioning evidence does the proposed system need? |
| G100 | A scheme to keep import or export within an agreed limit. | How will the installation enforce the agreed limit alongside its connection requirements? |
Example, for illustration: a larger inverter may be proposed with a lower permitted export level. The generating installation can require G99 approval while its export-limitation scheme follows G100. Selecting a low export setting does not, by itself, make the installation qualify for G98.
G98 vs G99: what is the difference?
G98 generally applies to fully type-tested microgeneration up to and including 16A per phase, subject to the other conditions of the standard. At a nominal 230V, 16A is 3.68kW per phase. G99 applies to larger generation and installations that do not qualify for G98.
The route depends on the generating equipment and the complete installation, including existing generation and battery storage. The solar panels’ DC peak rating in kWp is not, by itself, the figure that decides the connection route.
What is G98 notification?
For qualifying single-premises installations, G98 provides a simpler notification process. Your installer must follow the current requirements of the Distribution Network Operator (DNO) serving the property. Multiple premises and combined systems can have different requirements.
For local guidance, SP Energy Networks’ single G98 connection page explains its notification and commissioning-document requirements.
What is a G99 application?
A G99 application gives the DNO the technical information needed to assess a proposed generator or storage installation. The agreed design may include an export limit, protection requirements or network work. Obtain the required approval before connecting equipment that follows an apply-to-connect route.
Use the current SP Energy Networks G99 forms and guidance for installations on its network. The correct form depends on the project, and some small generation-and-storage combinations may qualify for a fast-track process.
What is G100 export limitation?
G100 addresses customer limitation schemes. For solar and battery installations, an export-limitation scheme controls how much power flows from the property to the distribution network. The agreed export limit can be lower than the installed generating capacity.
G100 does not mean that every installation must have zero export. Zero export is one possible agreed limit. A G100 scheme also does not automatically remove G98 or G99 requirements. See SP Energy Networks’ export-limitation guidance and our explanation of G100 for commercial solar.
What is a G98 or G99 certificate?
People often use “certificate” to mean different documents. Equipment type-test evidence concerns the inverter or generator model; the DNO notification, connection approval and commissioning records concern the installation. Ask your installer which documents apply to your system and retain them with your handover pack.
Does battery storage change the application?
Grid-connected batteries must be included in the assessment, even when the intention is to avoid export. Existing equipment and the combined design matter. The DNO’s energy-storage guidance explains the relevant connection considerations.
Help with solar and DNO paperwork in Scotland
Renew-Able Solutions designs and installs solar PV, battery storage and commercial solar systems. We assess the proposed installation and explain the relevant DNO process. Contact us about your project.
