This page covers how solar DNO applications work, what the network operator actually needs, how long it takes and where applications fall over.
Why solar needs a DNO application at all
The distribution network was built to move electricity in one direction: from the grid to the property. Solar reverses that. When a system exports, it pushes power back into a local network that was designed on the assumption it wouldn't be there.
That matters in aggregate rather than individually. One 4kW array on a street changes very little. Forty of them change the voltage profile of the whole feeder, and the network operator is the only party with visibility of how many are already connected. The application is how they keep track and, where necessary, refuse or restrict.
This is also why "the customer already has an MPAN" isn't an answer. The import MPAN tells the DNO nothing about generation. Export is a separate registration.
G98 or G99: which route your job takes
Two Energy Networks Association engineering recommendations govern this, and the split is by inverter output per phase.
Applies to micro-generation up to and including 16A per phase. In practice:
- Single phase: up to roughly 3.68kW
- Three phase: up to roughly 11.04kW
G98 is a notification, not a permission. You install, commission, and notify the network operator within 28 days. You don't wait for approval.
The important caveat: the threshold is on inverter output, not panel capacity. A 4.5kWp array on a 3.68kW inverter is a G98 job. A 3.6kWp array on a 5kW inverter is not.
More on G98 notificationsEverything above 16A per phase. G99 is a genuine application. You submit, the network operator assesses, and you do not install until it's approved.
Installing ahead of G99 approval is a real risk. If the DNO comes back requiring an export limit, a different connection arrangement or a network reinforcement contribution, you're changing a commissioned system at your own cost, with a customer already in occupation.
G99 is banded further by capacity — Type A covers 0.8kW up to 1MW and takes in almost all rooftop solar, with Types B, C and D applying to progressively larger installations.
More on G99 applicationsWhere the line gets blurry
Three situations catch installers out regularly:
Batteries
A battery is generation as far as the DNO is concerned. A 3.68kW inverter with a 5kW battery is not a G98 job by default — the combined rating is what counts, and the application route changes accordingly.
Export limitation
Fitting a G100-compliant export limiter can bring a larger system inside a lower threshold, but the limitation scheme itself has to be specified, evidenced and accepted. It isn't a checkbox.
Existing generation
If there's already solar, a battery or an EV charger with export capability on site, the assessment is cumulative. A second array on a property with an existing 3kW system is not assessed as a standalone 3kW system.
What the network operator actually asks for
The exact format varies by operator, but the substance is consistent:
Site and supply
- Full install address and postcode
- Import MPAN
- Phase configuration
- Details of any existing generation on site
Equipment
- Inverter manufacturer and model
- Rated output in kW and A per phase
- Type test certificate reference confirming G98 or G99 compliance
- Panel count and total array capacity in kWp
- Battery manufacturer, model and capacity where fitted
Export arrangement
- Whether the system is export limited
- The limit in kW and the scheme used to achieve it
- Evidence of G100 compliance where an export limiter is fitted
Documentation (G99, and sometimes G98)
- Single-line diagram
- Protection settings schedule
- Commissioning evidence
The type test certificate reference is worth particular attention. Inverter firmware revisions supersede certificates, and a reference that was valid last year may not be valid now. Submitting a superseded reference is one of the fastest ways to get an application bounced.
How long it takes
No waiting period. Notify within 28 days of commissioning. The export MPAN follows, typically within a few weeks, and the customer can't register for SEG until it lands.
The network operator has a statutory window to respond, commonly up to 45 working days for a standard distributed generation application. Some operators are considerably faster, fast-track routes exist for smaller Type A systems, and complex or constrained sites run longer. Where network reinforcement is required, the timeline extends well beyond the initial assessment.
The practical point for scheduling: a G99 job should have its application in before the install is quoted as a firm date, not after the scaffolding is booked.
When to submit — full guidanceWhy solar DNO applications get rejected
In rough order of frequency:
- 1
Wrong form for the configuration. Usually a phase or battery misjudgement.
- 2
Superseded or missing type test reference. The certificate exists, the reference quoted is out of date.
- 3
Export limitation described inadequately. "Export limited to 3.68kW" without the scheme, device and evidence behind it.
- 4
Existing generation not declared. The DNO can see it. You have to declare it.
- 5
Missing single-line diagram on G99 submissions.
- 6
Inconsistent capacity figures — array kWp, inverter kW and stated export limit that don't reconcile.
- 7
Unanswered queries. The application doesn't get rejected so much as abandoned, and drops out of the queue.
None of these are difficult problems. They're just easy to make when the application is the ninth thing on your list at seven in the evening.
The export MPAN
Approval and export MPAN are separate. The approval says the connection is permitted. The export MPAN is the registration number the customer's energy supplier needs to pay them for exported electricity under the Smart Export Guarantee.
It doesn't always arrive with the approval, and it doesn't always arrive without being chased. Until it does, the customer is exporting for free — which is usually the point at which they ring you.
Doing it yourself vs sending it out
You can absolutely run solar DNO applications in-house. Most installers start that way.
Realistically it's 2 to 4 hours per job once you account for form completion, portal handling, query responses and export MPAN chasing. Faster for routine G98, considerably slower for G99 with storage. That's before any rejection, and a rejection means a resubmission plus a return to the back of the queue.
The decision usually comes down to volume. Below two or three jobs a month, in-house is fine and you'll stay fluent. Above that, the applications start landing on evenings and weekends, fluency drops, and the errors above start showing up.
Grid Submit handles solar DNO applications end to end — form selection, submission, query handling, approval and export MPAN retrieval. Flat fee per application, seven day average turnaround, all UK network operators.
Hand your next application to us
Flat fee per application, seven day average turnaround, every UK network operator covered.
Frequently asked questions
Do I need a DNO application for a 4kW solar system?
Almost certainly. A 4kW system on single phase exceeds the 16A per phase G98 threshold, which puts it into G99 — apply and wait for approval before installing. On three phase, 4kW sits comfortably within G98 and can be notified after commissioning.
Can I install solar before DNO approval?
For G98, yes — it's notify-after-install with a 28 day window. For G99, no. Installing before approval risks having to modify a commissioned system if the network operator imposes conditions.
What happens if I don't submit a DNO application?
The system is connected unlawfully, the customer can't register for the Smart Export Guarantee, and it will surface at property sale or supplier switch. For MCS-certified installers it's also a compliance issue with your certification body.
Does a battery need a DNO application?
Yes. Batteries are treated as generation. Adding storage to an existing solar system usually requires a fresh application even where the panels were previously notified.
Who is my DNO?
It's determined by geography, not by who supplies the electricity. There are six distribution network operator groups across Great Britain, and the first two digits of the MPAN identify which one covers the site.
How long does a solar DNO application take?
G98 has no waiting period. G99 commonly runs up to 45 working days for the network operator's response, though many come back sooner and constrained sites take longer.
Can I do a DNO application without an MCS certificate?
Yes — the DNO application and MCS certification are separate processes. But without MCS the customer can't access the Smart Export Guarantee, so the export MPAN is of limited use to them.