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SolarWhat is a DNO, and why does a company you have never heard of get a say in your solar?
Your electricity supplier sells you units. A completely different company owns the wires those units arrive on, and it is that company, not your supplier, that decides how much solar you can connect.
Updated 4 August 2026 · written by the Clearline guidance team
Supplier and network operator are two different companies
The company on your bill buys electricity and sells it to you. It does not own a single metre of cable outside your house. That is the job of your Distribution Network Operator, or DNO, which owns and operates the regional cables and substations that carry electricity to homes in your area.
You do not choose your DNO and you cannot switch it. It is determined entirely by where you live. Great Britain has 14 licensed DNO areas, owned between six groups, and your postcode places you in exactly one of them.
You can switch supplier tomorrow. You will have the same DNO forever.
This is why the DNO conversation catches people out. Everything about the retail energy market is built on choice and switching, and then a monopoly network operator with no customer relationship gets the final word on your generation capacity.
How to find yours in under a minute
There are three routes, and any one of them will do.
- Use the Energy Networks Association postcode lookup tool, which returns your operator directly.
- Call 105, the free national number for power cuts and network enquiries, which routes you to your regional operator automatically.
- Read your MPAN. On the bottom line of the long reference number on your bill, the first two digits are your distributor identifier.
The MPAN trick
MPAN stands for Meter Point Administration Number. It is the long block of digits on your electricity bill, arranged in a grid. The bottom line starts with a two-digit distributor ID, and that ID maps to one of the 14 DNO areas. If you are on the phone to an installation team, this is the fastest way to answer the question.
What your DNO actually controls
One thing, essentially: what you are allowed to connect to the network, and under what process. Solar panels do not just draw electricity, they push it back, and the network was designed for flow in one direction. The DNO's job is to keep the local network stable as more generation appears on it.
| Your inverter capacity | Process | What happens |
|---|---|---|
| 3.68kW per phase or less, which is 16A per phase | G98 | Connect and notify. The system is fitted first and the form goes to the DNO within 28 days of commissioning |
| Above 3.68kW per phase, or above 11.04kW on three phase | G99 | Approval required before installation. Standard determination is roughly four to eight weeks |
G98 and G99 threshold and process guidance, accessed August 2026. The threshold applies to inverter AC rating per phase, not to panel capacity.
Note what is being measured there. It is the inverter's AC rating, not how many panels you have, which is why a well-designed system often carries far more panel capacity than the inverter number suggests. That is covered in inverter sizing explained, and the two processes are compared in full in G98 versus G99.
What it does not control
- Planning permission. That is your local authority, and it is a separate question entirely.
- Your export tariff. That is your electricity supplier, and rates differ enormously between them. Our tariffs guide carries the current picture.
- How many panels you fit. The DNO regulates connected generation capacity at the inverter, not the roof.
- Who installs it. Installations are carried out by an MCS-certified installation team for your area, and the DNO has no say in who that is.
Does it ever say no?
Under G98 it effectively cannot. A properly completed G98 notification cannot be rejected, because the system sits below the threshold at which the DNO has discretion. Under G99 it can, and occasionally does, though outright refusal is not the usual outcome.
More common is a condition. The DNO may require network reinforcement, which in rare cases is paid for by the applicant. Where a G99 is refused, the options are to fund the upgrade, cap the inverter at 3.68kW using export limitation, decline the connection, or reapply later when the local network has changed. The application itself is free, although installers may charge an administration fee for handling it.
Do you have to deal with any of this?
No. In a standard installation the homeowner files nothing. The installer handles G98 and G99 end to end, from application through to the commissioning paperwork, and the first most people hear of their DNO is when someone explains why the inverter is 3.68kW.
The reason it is worth understanding anyway is timing. A G99 adds weeks to a project, and knowing that up front lets you plan around it rather than discover it. Our solar panels guide sets out the full sequence from first call to commissioning.
Not sure which process your system needs? A free design call will size the inverter, name the process and give you a realistic timeline before you commit to anything.
Get your free quote →Regional differences are real
Fourteen operators means fourteen sets of internal processes, workloads and local network conditions. Determination times, appetite for larger connections and how quickly reinforcement gets flagged all vary between areas, which is one reason a national average timeline is only ever a guide.
Every county page on this site carries a calculator built for that area, so you can model a system against local conditions before you speak to anyone. Start at your county page, and if a term on your quote still does not make sense, our help centre works through the common ones.
DNOs, answered
What does DNO stand for?
Distribution Network Operator. It is the company that owns and operates the regional cables and substations carrying electricity to homes in your area. Great Britain has 14 licensed DNO areas owned between six groups.
Who is my DNO?
It is set by where you live, not by choice. Find yours using the Energy Networks Association postcode tool, by calling 105, or by reading the first two digits of the bottom line of the MPAN on your electricity bill. All three routes give the same answer.
Is my DNO the same as my energy supplier?
No, and they are usually completely different companies. Your supplier buys and sells you electricity and you can switch it whenever you like. Your DNO owns the physical network, cannot be switched, and is the body that regulates what generation you can connect.
Can my DNO refuse my solar installation?
Under G98, a properly completed notification cannot be rejected, because the system sits below the threshold at which the DNO has discretion. Under G99 it can impose conditions or, occasionally, refuse. In that case the options are to fund network reinforcement, cap the inverter at 3.68kW, decline the connection, or reapply later.
Do I have to contact my DNO myself?
Not for a standard installation. The installer handles the G98 notification or the G99 application from start to finish, including the commissioning paperwork. It is worth knowing which process applies purely because a G99 adds weeks to the project timeline.
Does it cost anything to apply?
The application itself is free, though installers may charge an administration fee for preparing and submitting it. In rare cases a G99 outcome requires paid network reinforcement, which is a separate and potentially significant cost. That risk is one of the things worth establishing early on a larger system.
See the numbers next: LONGi 530 W panels, installed, or the solar panels guide.
Figures and specifications in this guide are sourced below and were checked on the date shown. Rates and product specifications change; we confirm the current picture on your free design call.
Sources
- What a DNO is and how to find yours, including the 105 number ovoenergy.com
- Fourteen licensed DNO areas in Great Britain owned by six groups en.wikipedia.org
- Finding your DNO by postcode and via the MPAN distributor identifier uw.co.uk
- G98 connect and notify: threshold, 28 day submission, cannot be rejected when properly completed sunsave.energy
- G99: prior approval, four to eight week standard determination, free application, refusal options including export limitation sunsave.energy
- The threshold governs inverter AC rating per phase, not panel kWp sunsave.energy
- Three phase connect and notify limit of 11.04kW blog.spiritenergy.co.uk
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