What is a DNO, and why does it sit between you and your solar?

The DNO is the licensed operator of the local distribution network in your region: the medium and low-voltage cables, the substations, the transformers and the connection that brings power from the high-voltage transmission system down to your building. They do not generate electricity and they do not sell it. They run and maintain the wires.

Great Britain is split into regions, and each one has a single DNO responsible for its network. Several regional network operators own these licences between them, so the DNO you deal with is fixed by where your site sits, not by who you choose. You cannot shop around for a different one. This is a regulated regional model, overseen by the energy regulator, which is why the process for connecting generation is broadly consistent across the country even though the operator changes by region.

Your electricity supplier is the company on your bill. You can switch supplier whenever a contract lets you, because the supply market is competitive. The DNO is not part of that market. It is the regional owner of the physical network, and it stays the same no matter which supplier you use.

The distinction matters for solar because the two have separate roles in a project. The supplier handles the commercial side of any energy you import or export, including export payment arrangements. The DNO handles the technical question of whether the network can physically accept your generation, and under what conditions. A solar array is a generator connecting to their wires, so their permission comes first, and the supplier arrangements follow.

• DNO: owns the local network, approves and engineers the connection, fixed by region.
• Supplier: sells you energy and settles import and export, chosen by you, switchable.

Putting generation onto a shared network is not a neutral act. Your array pushes power back towards the grid at times, and the DNO has to be satisfied that doing so will not affect voltage, capacity or safety for you and for everyone else on the same local network. The larger the system, the more this matters. A commercial array, by its scale, sits above the size where a generator can simply be notified, so it goes through a formal connection process rather than a light-touch route. That formal route is set out in the grid framework as ENA Engineering Recommendation G99, which governs commercial connection and export, while the lighter notification route under G98 covers smaller systems.

That process means an application to the DNO, a technical assessment of your site against the network, and a connection agreement that sets out what you are allowed to connect and on what terms. Sometimes the network can take the full system with no changes. Sometimes the DNO sets an export limit, or identifies reinforcement work, that shapes the design. Either way, the array is engineered around their answer, so the application sits early in the project, not at the end. Which application route applies depends on your system's capacity and connection point, and we confirm it for your site rather than assume it.

The practical takeaway is that the DNO connection is a lead item, not a formality you tidy up before switch-on. The application and the agreement that follows take time, and the answer can influence system size, export arrangements and occasionally cost. We treat it as a parallel workstream alongside survey and design so it is not the thing that holds a project back.

We handle the DNO application for your site as part of the engineering package, including the technical detail the operator needs and the connection agreement that results. The specifics of which DNO applies, which application route fits your system, and what the network can accept are confirmed against your actual site rather than assumed from a regional average.

The regional model is a licence rather than an open market. A Distribution Network Operator holds an electricity distribution licence granted under the framework administered by the regulator, Ofgem. That licence gives one operator the exclusive right and the statutory duty to run the distribution network across a defined geographic area, which is why generation cannot be put out to tender between competing wire owners the way energy supply can. For sites across Yorkshire and northern and north-east Lincolnshire the licensed operator is Northern Powergrid. Across Greater Manchester and Lancashire it is SP Electricity North West, the name Electricity North West adopted in 2025. That allocation follows the boundary of the licence area rather than any commercial preference, so the operator you deal with is decided by where your site sits.

The monopoly is balanced by regulated obligations. Because a single operator controls each network, Ofgem sets the price controls and connection obligations the operator must work within, under the price-control framework the regulator publishes for distribution networks. Those obligations govern how an operator must treat a connection request, the standards it must meet, and the principles behind the charges it can recover. The Energy Networks Association, the body representing the network operators, publishes the technical Engineering Recommendations that sit underneath this, so the connection rules an operator applies are common across the country even though the operator changes by region. The practical effect for a buyer is that the process is predictable in shape, and the operator you engage is settled the moment your site address is known.

The application is a technical submission, and the offer is the operator's formal answer. A commercial array applies to connect under the relevant ENA Engineering Recommendation, and the operator assesses that submission against the real state of the local network at your proposed point of connection. What comes back is a connection offer, a document that states the export capacity the operator will permit, any conditions attached to it, any network reinforcement it considers necessary, and the indicative cost and timescale that go with each of those. The mechanics of preparing and lodging that submission are set out in our G99 application guide.

An offer is time-bound, so it has to be read and acted on, not parked. A connection offer typically carries a fixed acceptance window and a price that holds only inside that window, which means leaving it open while other decisions catch up can let it lapse. Before anything is signed, the figures worth checking are the permitted export capacity against your modelled surplus, whether any reinforcement is attributed to your project specifically, the protection and metering obligations, and any commissioning conditions that gate switch-on. The export side that the offer governs is metered as set out in our half-hourly metering guide, and where the offer constrains export rather than reinforcing the network, the design route is covered in export limitation. We read the offer with you and translate its conditions into plain commercial terms before any capital is committed.

Network cost is a survey-led outcome that no price list can anticipate. Whether your connection carries a network charge depends on what the operator finds when it assesses your site against the local network. Sometimes the existing network can accept the full system with no changes. Sometimes the operator identifies reinforcement, which can mean upgrading a cable, a transformer or a substation, and on a constrained network can reach back to higher-voltage infrastructure. Where that work is required it carries a charge and a lead time, and both are specific to your connection point rather than something that can be quoted from a regional average. The principles that decide who pays for reinforcement and how those charges are calculated are set at industry level under Ofgem and applied by the operator that holds your licence area.

Design choices can move a connection from reinforcement to acceptance. An export-limitation scheme can hold a site within the capacity the network already has, so a larger array can sometimes connect without waiting on or paying for reinforcement. That trade-off is set out in our network charges guide, and where the network is busy the position is also bound up with the grid connection queue. Because the network side is genuinely site-specific, we do not attach a figure to it in advance. How the connection outcome feeds into the wider project budget is handled in our commercial solar cost guide, where every number is built from your actual site rather than a table.

The route depends on capacity and connection point, and it is confirmed for your site. Generation connecting to the distribution network is assessed against thresholds set in the ENA Engineering Recommendations. A commercial array is large enough that it goes through the formal application route under G99 rather than the lighter notification process that covers smaller systems, and the depth of the assessment then scales with the size and connection voltage of the scheme. Rather than assume a threshold or a route from a regional average, we confirm which one applies against your actual system and connection point before any work is committed, because treating a regulatory boundary as settled when it has not been checked is exactly the kind of orientation error this guide exists to avoid.

You engage the operator through us as a managed workstream. RVTC Installations Ltd prepares and lodges the connection application for your site as part of the engineering package, including the technical detail the operator needs, and we run it as a parallel workstream alongside survey and design so it does not become the item that holds a project back. When the offer returns we read it with you, check its capacity, conditions and any attributed reinforcement, and build the design around what the network can accept. As a commercial installer working above 50 kWp and outside the MCS scheme that applies to smaller domestic-scale systems, we assure the work through the non-MCS commercial stack rather than through MCS, and the DNO connection sits inside that same managed process from application through to the conditions that gate switch-on.