Yes, every solar or battery system connected to the grid needs your DNO to be told or to say yes. Systems up to 16 amps per phase (3.68kW on a normal single-phase home) go through G98, which is a notification within 28 days of switch-on. Anything bigger needs G99 approval before we install.
Not sure how to judge an installer? Martin Lewis's advice is covered in what Martin Lewis says about solar panels, including how to check an installer's reviews.
Watch: DNO approval in a nutshell
What is a DNO?
A DNO is your Distribution Network Operator, the company that looks after the local electricity network between the big power lines and your meter. It isn't your energy supplier. You can't switch it, and you don't pay it a bill.
There are six DNO groups in Great Britain. Here in Hampshire it's SSEN. Not sure who covers you? Your meter point number (the MPAN on your bill) tells you, or you can call 105 and ask.
The network was built for power flowing one way, from the power station to your house. Solar and batteries push power back the other way, so the DNO needs to know what's being connected and check the local cables and transformer can take it.
Do I need DNO approval for solar panels?
Yes. There's no size of system that skips it entirely. What changes is whether you tell them after, or ask first.
G98 or G99: which one applies?
The dividing line is 16 amps per phase, counted across everything you've got, panels and battery together. It isn't per device.
| Detail | G98 | G99 |
|---|---|---|
| Size limit | Up to 16A per phase (3.68kW single-phase, 11.04kW three-phase) | Above 16A per phase |
| When you apply | After installation | Before installation |
| Wait before install | None | Yes, until the DNO approves |
| Timescale | Notify within 28 days of commissioning | Around 45 working days for a full application |
| Outcome | Notification acknowledged | Approval, sometimes with an export limit |
Does battery storage need DNO approval?
Yes, and it counts towards the same limit. A battery on its own is notified or approved the same way as panels. If you're adding a battery to an existing system, the combined total is what decides between G98 and G99, so a system that was fine before can cross the line when the battery goes in.
What if the DNO won't allow the full export?
You can still go ahead. The DNO can approve the system with an export limit, so it generates as normal and powers your home, but only sends a set amount to the grid. The limit is enforced by a G100 device that watches your export and holds it down.
For most homes this costs very little, because a lot of your solar goes into the house or the battery anyway. A battery makes an export limit even easier to live with.
If the network in your area is stretched, the DNO might instead offer approval only if reinforcement work is paid for. We'd talk that through with you before anything is committed.
Who applies for DNO approval?
We do. Getting the paperwork right is part of the installation, so you don't fill in anything except a signature. If it's a G98, we notify the DNO after commissioning. If it's a G99, we submit the application at the design stage and you don't get an install date until it comes back.
How long does DNO approval take?
G98 is quick, because you install first and notify afterwards. G99 is the one that can hold a job up. A full application has around 45 working days for the DNO to reply, and if they want a network study it can take longer. Smaller G99 systems can sometimes go through a fast-track route that takes a couple of weeks.
Rejections are usually down to paperwork. Wrong inverter details, a missing single-line diagram, or the wrong DNO region on the form. It's the boring stuff, which is why we submit them ourselves.
What does a DNO application include?
- Your address and MPAN
- Panel, inverter and battery make, model and capacity
- The AC output of the whole system
- A single-line diagram of the electrical layout
- Details of any export limiting device
- Contact details for the installer and the homeowner
Planning solar panels or battery storage?
We'll work out whether you're on the G98 or G99 route, handle the DNO application, and tell you honestly how long it's likely to add. Book a free survey and we'll take it from there.
