Question 1

What's the difference between G98 and G99?

Accepted Answer

G98 covers small systems up to 16A per phase (around 3.68kW single phase or 11kW three phase). You install first and notify the DNO within 28 days. Anything larger falls under G99, which needs DNO approval before installation.

Question 2

Do I need a single line diagram (SLD)?

Accepted Answer

Most G99 applications need one. If you don't have your own, we can draw a standard SLD for £50 + VAT, and add it with one click when you apply.

Question 3

How long do DNOs take?

Accepted Answer

It depends on the DNO and the size of the system. G98 notifications are usually acknowledged within days. G99 decisions typically take several weeks. The finder shows the median time for your DNO from applications on our platform where we have enough data.

Question 4

What if I'm adding to an existing system?

Accepted Answer

Tell us what's already installed. The DNO looks at the total generation at the property, so adding to an existing system can move a G98 into G99. We include the existing equipment in the application and SLD.

Question 5

Is the recommendation final?

Accepted Answer

It's our best guide from your answers. An engineer checks every application before submission and will confirm the right route once we have the full project details.

Not sure which application you need?

What are you installing? Pick all that apply.

Common questions

What's the difference between G98 and G99?

Do I need a single line diagram (SLD)?

How long do DNOs take?

What if I'm adding to an existing system?

Is the recommendation final?