"DNO letter" or "DNO certificate"?
People use "DNO letter", "DNO certificate", "DNO approval letter" and "DNO acceptance letter" for the same thing: the DNO's written confirmation for your site. There is no single official document with one of these names, and it often arrives as an email or a PDF rather than anything on letterhead.
What matters is the content. It should name your site, the capacity in kW and any conditions the DNO has attached.
Which one will you get? G98 vs G99
What comes back from the DNO depends on which route the installation takes.
| Topic | G98 (up to 3.68kW per phase) | G99 (above that, or any larger or more complex system) |
|---|---|---|
| Route | Install first, then notify the DNO ("connect and notify") | Apply and wait for approval before you install |
| What we send | Notification (Form B), single line diagram (SLD), letter of authority if we act as agent | Application form, SLD, site boundary plan, letter of authority, plus datasheets and any export limitation (G100) details |
| What you get back | Acknowledgement or confirmation of the notification | Approval or connection offer, then confirmation after commissioning |
| Typical wait | Often just an acknowledgement. Chase if you hear nothing (see common problems) | Weeks to months, depending on the DNO and the network |
| What your supplier wants | The DNO's confirmation for SEG | The DNO's approval and commissioning confirmation for SEG |
What a DNO letter looks like
Below is an illustrative example. The numbers mark the details worth checking on any letter or email you get back.
Example DNO confirmation letter (illustrative)
[Network operator name]
Licence area: [Region]
Our reference: [DNO reference]
Site: [Installation address]
Import MPAN: [13 digits]
Export MPAN: [13 digits, if issued]
[Approval / Connection offer / Commissioning confirmation]
We confirm that the generation described below may be connected to our network, subject to the conditions listed.
Generation capacity: [x] kW
Maximum export: [y] kW
Conditions
a) Export limited by a G100 scheme
b) [Phase balancing / other]
c) Commission by [date]
Date: [Date of letter]
Valid until: [Date]
An illustrative, generic DNO confirmation letter with eight numbered fields, explained in the list below.
- DNO name and licence area. Check it is the right operator for the site.
- Their reference number. Quote it in every chase.
- Site address. It must match the property.
- MPAN: import, and export if there is one.
- Approved capacity (kW) and, if relevant, the export limit (kW).
- Conditions, such as a G100 export limitation device, three-phase balancing or a commissioning deadline.
- Date and validity. Offers can lapse.
- Whether it is an approval, an offer or a commissioning confirmation.
Every DNO words and formats this differently. This is a guide to what to look for, not a template.
How to get your DNO letter
- 1
Find your DNO. Use the MPAN on your electricity bill. Our Find My DNO tool gives an exact answer from it.
- 2
Work out G98 or G99. See our guides to G98 notifications and G99 applications.
- 3
Submit the paperwork. G98: install, then notify. G99: apply first and wait for the DNO's answer.
- 4
Respond quickly to the DNO's questions. Several DNOs close enquiries if you don't answer within about 10 working days (see the NGED example).
- 5
Commission and send the commissioning form. For G99 these are the A3 series forms.
- 6
Keep the letter safe, then take it to your supplier to request an SEG tariff. Mention the export MPAN too.
Installer? Don't chase DNOs yourself.
We submit and chase G98 and G99 applications for you, and send you the DNO letter when it arrives.
What DNO letters and offers really look like: examples from our files
We submit DNO applications for installers every week. These are anonymised examples from 2026 showing what comes back, and what slows it down.
UK Power Networks (UKPN)
Eastern, London and South Eastern England
When the answer isn't yes or no
A homeowner in the East of England wanted 50kW of new solar alongside 3kW already installed, on a single-phase supply. They already held a quote for a three-phase upgrade, but wanted to know the network could take the generation before paying for it.
We submitted the G99 first. UKPN allocated a local designer within days, and about two weeks after submission came back with three routes:
- Three-phase upgrade: maximum 26.9kW total generation (including the existing 3kW), export limited to 7kW with a G100 device.
- Stay single-phase: 6kW export under their automatic approval process.
- Network reinforcement: a new pole-mounted transformer from the local 11kV overhead line, estimated at £40,000 or more and 4 to 6 months.
UKPN also put the project on hold for 10 working days so the customer could decide.
Also seen: UKPN asked us to allow 48 working hours before calling the designer.
SSEN
Southern England (including parts of Hampshire, Dorset and Berkshire) and the north of Scotland
Three months to a quote, and the letter you must not lose
North of Scotland, G99: a G99 for a house, submitted in July, was registered quickly, but the quote was still with the design team in October, after several chasers. During the chase the DNO said it already had an earlier approved application for a 12kW system balanced across two phases, which had never been commissioned. We had to track down the original approval letter before commissioning could go ahead.
Southern England, G98: an installer planning several G98 installations in the same area was told the DNO does not allow multiple G98 installs within a 28-day window and that they must be installed one at a time.
Also seen: on a commercial site in the south, the DNO needed the SLD to match the application exactly, and we also asked it to generate an export MPAN at commissioning.
Northern Powergrid (NPg)
North East England and Yorkshire
Two months to a commissioning confirmation
An installer asked us to increase the export capacity on an existing commissioned system in the north east. We submitted the G99 in May and sent the commissioning documents in mid-July.
With no confirmation after several weeks, the installer was chasing us, so we phoned NPg, who confirmed they had logged the forms and would chase internally. The confirmation letter arrived in mid-September, about two months after the commissioning submission.
Electricity North West (ENWL)
North West England
The clean run
A G99 for a domestic system in Greater Manchester was submitted on 23 July and registered the same day, passed to a design engineer, and a quotation was promised under their published service levels.
After installation we sent the commissioning form and SLD on 17 August. On 25 August ENWL confirmed it had reviewed the documents, nothing further was required, and the customer should take the approval letter to their supplier and request an SEG tariff.
SP Energy Networks (SPEN)
Southern Scotland, Cheshire, Merseyside and North Wales
EV chargers change the application
Glasgow, G99 plus EV chargers: a solar and storage application with six 22kW EV chargers sharing load on a 63A three-phase supply. There was no obvious route for multiple chargers in one application, so we queried SPEN first. Once submitted, the project was registered and passed to their design team within three days.
Edinburgh, G99 with an EV charger and heat pump form: the DNO quoted its 45 working-day assessment allowance. At day 22 it set a completion date of late October.
Cheshire: an installer restricted a 6kW inverter to 3.68kW so the job could go through as a G98 notification with a restricted SLD instead of a G99.
National Grid Electricity Distribution (NGED)
East Midlands, West Midlands, South West England and South Wales
Fast track refused, then a 5kW export limit
A G99 for a 10kW system in the Midlands was submitted at the end of July. The next day NGED's planner said it could not fast track the approval and a full network analysis was needed, with a target date at the end of September.
In early August the full analysis came back: 10kW generation allowed, but export restricted to 5kW. They needed an updated schematic, a CLS form and a G100 device, with 10 working days to reply or the enquiry would be closed.
The customer accepted, the offer was signed, and we sent the commissioning documents. NGED then asked for payment before proceeding with commissioning and queried the 5kW limit, even though it was shown on the commissioning form, SLD and G100 form.
Elsewhere in the south west, a G98 notification went unacknowledged for about three weeks until we re-sent it, and NGED asked for a meter serial number and a recent bill to confirm the MPANs were linked to the property.
At a glance: what we see by DNO
| DNO | What we see most | Chase tip |
|---|---|---|
| UKPN | Offers with options and conditions, not a simple yes | Apply before ordering kit or a supply upgrade |
| SSEN | Long waits for G99 quotes; old approvals still on file | Keep every letter; check how many G98s are planned in one area |
| NPg | Slow commissioning confirmations | Log the send date and phone at 2 to 3 weeks |
| ENWL | Fast confirmation when the paperwork is right | Get the commissioning form and SLD right first time |
| SPEN | Extra forms for EV chargers and heat pumps | Query unusual set-ups before submitting |
| NGED | Full network analysis and lower export limits | Read the export limit before ordering kit; pay fees promptly |
Common problems and fixes
"I've heard nothing from the DNO."
Resend after about 3 weeks, quoting the date of the first submission. For commissioning forms, phone after 2 to 3 weeks.
"The DNO says it needs more information."
Typical asks are loop impedance results, a meter serial number and a recent bill (to confirm the MPANs match the property), an updated SLD, or G100 details. Answer quickly: some DNOs close enquiries after about 10 working days.
"The offer limits my export."
Check the kW in the letter against what you ordered. The options are usually to accept the limit with a G100 device, change the design, or pay for reinforcement.
"The DNO wants payment before commissioning."
Pay it, and send proof of payment to the DNO.
"I've lost the letter."
Ask the DNO, quoting the reference, or the installer who received the original. A lost approval can hold up commissioning.
"Several G98s in one area."
Install and notify one at a time.
Installer? Don't chase DNOs yourself.
We submit and chase G98 and G99 applications for you, and send you the DNO letter when it arrives.
Using your letter: SEG and the export MPAN
Your energy supplier will want the DNO's confirmation before it sets up a Smart Export Guarantee tariff. For a G99 that usually means the confirmation after commissioning, not just the original approval.
Many DNOs also issue an export MPAN at or after commissioning. It is a separate number from your import MPAN, it doesn't always arrive with the letter, and the supplier usually needs both. Our guide to solar export numbers explains what it is and how to chase it.
Frequently asked questions
What is a DNO letter?
A DNO letter is the written confirmation from your Distribution Network Operator that your solar, battery or EV charger installation has been approved or accepted onto the local network. For a G98 installation it is the acknowledgement of your notification. For a G99 installation it is the approval or connection offer, followed by confirmation after commissioning. Energy suppliers normally ask for it before setting up a Smart Export Guarantee tariff.
Is a DNO letter the same as a DNO certificate?
In practice, yes. DNO letter, DNO certificate, DNO approval letter and DNO acceptance letter all describe the network operator's written confirmation for your site. There is no single official document with one of these names, and it often arrives as an email or PDF. What matters is that it names your site, the approved capacity in kW and any conditions.
What does a DNO letter look like?
Every DNO formats it differently, and many send it as an email or PDF. Look for the DNO's name and licence area, their reference number, the site address, the MPAN, the approved capacity and any export limit in kW, conditions such as a G100 export limitation device, the date and validity, and whether it is an approval, an offer or a commissioning confirmation. See the annotated example above.
How do I get a DNO letter?
Find your DNO from the MPAN on your bill, then work out whether the system is G98 or G99. For G98 you install and then notify the DNO. For G99 you apply and wait for the DNO's answer before installing. Answer any questions from the DNO quickly, send the commissioning documents, and keep the confirmation safe for your energy supplier.
How long does it take to get a DNO letter?
It depends on the route and the DNO. A G98 notification usually just gets an acknowledgement, though you may need to chase it. A G99 can take weeks to months. On one of our recent applications, SP Energy Networks quoted a 45 working-day assessment allowance. Network studies, export limits and reinforcement add time, so apply for a G99 before ordering equipment.
Do I need a DNO letter for the Smart Export Guarantee?
Usually, yes. Energy suppliers normally ask for the DNO's confirmation before they set up a Smart Export Guarantee tariff, and many also want the export MPAN. For G98 that is the acknowledgement of your notification. For G99 it is the approval and the commissioning confirmation. Check exactly what your chosen supplier asks for, because requirements vary.
What if I've lost my DNO letter?
Ask the DNO for a copy, quoting their reference number if you have it, or ask the installer or agent who received the original. Don't leave it: a lost approval can hold up commissioning. We have seen a DNO pause a new application because an earlier approval for the same property had never been commissioned, and the original letter had to be found first.
Who is my DNO?
Your DNO is set by where the property is, not by who supplies your electricity. The quickest exact answer is the first two digits of the 13-digit MPAN on your bill, which identify the licence area. Our free Find My DNO tool looks it up from your MPAN, or gives an estimate from your postcode.
Can an installer or agent get the letter for me?
Yes. Most DNO paperwork is submitted by the installer or an agent. We act as agent with a letter of authority from the customer, so the DNO replies to us, we answer its questions, and we pass the letter on when it arrives. The customer ends up with the same confirmation to give their energy supplier.
What if the DNO refuses or limits my export?
Read the letter before ordering equipment. A DNO can approve less generation or export than you asked for, or offer options with conditions. The usual choices are to accept the limit with a G100 export limitation device, change the design (for example a smaller inverter or a three-phase supply), or pay for network reinforcement. Reply within the DNO's deadline or the enquiry may close.
Installer? Don't chase DNOs yourself.
We submit and chase G98 and G99 applications for you, and send you the DNO letter when it arrives.