Rules & permissions
What is a DNO? Applications, letters and solar
A DNO — distribution network operator — is the company that runs the local electricity network your home is physically connected to. It isn't your supplier, you don't choose it, and most people never deal with it — until they connect generation like solar.This guide explains what DNOs do, what "DNO applications", "DNO letters" and "DNO certificates" actually are, and how the DNO fits into the plug-in solar question. It pairs with G98 notification explained.
Written and edited by Christopher Panteli
Christopher is the founder and editor of MyPlugInSolar. He oversees the site’s research standards, data tools and editorial process. He is not an electrician or solar installer, and specialist technical claims are sourced from official documentation or reviewed by appropriately qualified professionals.
DNO vs supplier: who does what
Your electricity supplier is the company you pay bills to, and you can switch it. Your DNO is the regulated company that owns and maintains the cables, substations and connections in your region — you cannot switch it, because it is determined by geography. Great Britain is covered by a handful of DNO groups (including National Grid Electricity Distribution, Northern Powergrid, UK Power Networks, SP Energy Networks, Scottish and Southern Electricity Networks and Electricity North West), plus smaller independent operators (IDNOs) on some newer developments. Northern Ireland is served separately by NIE Networks — see plug-in solar in Northern Ireland.
The Energy Networks Association runs a postcode look-up to find your operator, and the number on your meter or a power-cut call (105) also routes to it.
DNO applications, letters and certificates
Solar owners meet the DNO because anything that generates onto the network has to be notified to, or approved by, the network's operator:
- G98 — for small systems (up to 16A per phase, roughly 3.68kW): the installer notifies the DNO after commissioning. See G98 notification explained.
- G99 / "DNO application" — for larger systems: an application to the DNO before installation, with approval needed first.
- "DNO letter" or "DNO certificate" — the acknowledgement (G98) or approval (G99) document. Suppliers commonly ask for evidence of DNO notification when registering for Smart Export Guarantee payments, and it can come up when selling a house with solar.
Lost your DNO letter?
Where plug-in solar fits
Plug-in solar is small enough that, in principle, it would sit at the G98 end of this system — but how (or whether) DNO notification will apply to socket-connected systems is one of the open questions from the Government's consultation, which closed on 30 June 2026 with a response awaited. Plug-in solar remains not yet legal to sell, supply or use in the UK, so today there is no plug-in notification route to follow. Grid-protection behaviour like anti-islanding is part of why the notification system exists at all.
Frequently asked questions
- What does DNO stand for?
- Distribution network operator — the regulated company that owns and runs the local electricity network in your region. It is separate from your supplier: the DNO moves the electricity, the supplier bills you for it, and only the supplier can be switched.
- How do I find out who my DNO is?
- It is set by where you live. The Energy Networks Association provides a postcode look-up for your network operator, and calling 105 (the power-cut number) also connects you to it.
- What is a DNO letter for solar panels?
- It is the document showing your system was properly notified to (G98) or approved by (G99) the network operator. Energy suppliers often ask for it when you register for Smart Export Guarantee payments, and it can be requested during a house sale.
Sources
- 1. Find my network operator / Engineering Recommendations G98 and G99 — Energy Networks Association
- 2. Network operators and distribution licensing — Ofgem
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