GUIDE · FOR UK SOLAR INSTALLERS · 10 MIN READ

DNO Application for Solar: Which DNO and How to Apply

Every rule and figure below comes from the ENA and network operator sources listed at the end.

What a DNO is, and IDNOs

A Distribution Network Operator owns, operates and maintains the public electricity network in a region under licence; the ENA counts six in Great Britain. It isn't the energy supplier: the DNO looks after the cables and decides whether your generation connects.

An Independent Distribution Network Operator (IDNO) runs network extending a DNO's, typically on new developments such as business parks. IDNOs have no service area, and the ENA says connecting to one is almost identical to connecting to a DNO. Northern Ireland has its own G98/NI and G99/NI, run by NIE Networks.

Which DNO am I? Postcode and MPAN

Two quick checks, best done at the survey:

• Postcode. The ENA's Who is my network operator? finder returns it from a postcode; SSEN and others have their own checkers.
• MPAN. The first two digits of the MPAN on the bill are the distributor ID: in the ENA's table, 10 to 23 are the regional DNOs, 24 and above IDNOs.

No meter yet? The ENA guide says to ask the DNO whose area you think the site is in.

The DNOs and where to apply

Licence areas and MPAN IDs from the ENA guide, with each operator's generation page (opened 7 October 2026).

IDNOs (MPAN IDs 24 to 43 in the ENA table) follow the same G98 and G99 process; contact the IDNO named by the MPAN.

G98, G99, fast track or G100?

For inverter-connected solar and batteries the route depends on the total capacity at the site. Fast-track tiers are from NGED's guidance; UK Power Networks and Northern Powergrid use the same SGI categories.

Batteries count: DNOs treat storage as generation, so PV plus a battery is likely to tip a site into G99, and storage built to run in island mode can't use the fast track. NIE Networks says its G99/NI Fast Track parameters changed on 1 May 2026, so check its page for Northern Ireland.

The detail of each route is in our guides to G98 notification, limits and forms and the G99 application for commercial solar, including G99 Types and commissioning.

What to submit

The ENA guide expects the installer to submit for the customer. Across the DNOs, have ready:

• The right ENA form for the route, plus any supplementary data sheets.
• A single line diagram (Electricity North West asks for one with every G99 application).
• A site layout plan with the point of supply marked (SSEN).
• A letter of authority if the applicant isn't the landowner or occupier (SSEN).
• Make, model and size of the equipment and inverter, and whether the supply is single- or three-phase (NIE Networks).
• Type test evidence for each inverter, or the compliance forms if it isn't Fully Type Tested.
• For a battery: type, rating, capacity, import and export capacities and operating modes.
• An export limitation scheme form if you are capping export.

After commissioning, Electricity North West wants the A3-1 document, a single line diagram, G100 Form C if export is limited and, over 50kW, a G5 harmonics report, approved before switch-on. Over 30kW of export you need an export MPAN.

Most of this comes from the site visit (see our commercial solar survey checklist) and your solar design software; check each inverter's type test status when ordering from UK solar wholesalers. The DNO paperwork runs alongside MCS certification.

G100 export limitation explained

An export limitation scheme caps what a site sends to the grid. EREC G100 sets the technical rules for customer export (and import) limitation schemes, and the ENA guide says any scheme must comply.

How it works. NGED describes a scheme that measures power at the installation's exit point and turns generation down or raises demand so export never exceeds the agreed figure. SP Energy Networks says a scheme can combine both.

When DNOs accept it. NGED says it may suit customers told that more export would need costly or slow reinforcement. It is also built into the SGI-2 and SGI-3 fast tracks. SPEN takes schemes through the G99 application with an export limitation form, may witness commissioning (fees apply), and warns a supply upgrade can still be needed.

Fail-safe and settings. NGED's guidance, referring to EREC G100 Issue 2 Amendment 2, says the scheme must be fail-safe: if any component or signalling link fails or loses power, export must drop to the agreed capacity, typically within 15 seconds and at most 60. Settings are locked by password, PIN or a sealable enclosure and change only with the DNO's written agreement. The ENA's 2025 guide adds that G100 devices for G99's small-installation procedures must now be Fully Type Tested.

Capacity maps and pre-application advice

The ENA guide says every DNO publishes capacity heat maps and similar data, and some run generation surgeries. Before you quote anything large:

• SSEN says says 50kW or less generally avoids constraints; above that, check its Centralised Network View map.
• UK Power Networks has a Network Infrastructure and Usage map, open data and DER surgeries.
• NGED points to its Network Opportunity Map, Embedded Capacity Register and connection surgeries.
• Northern Powergrid has a self-serve budget estimator.

A budget estimate is a desktop exercise and can't be accepted; a formal quotation can. On a big roof, get one before the proposal.

Timescales and costs

Standards for individual stages, not a connection date.

On cost, the ENA guide says DNOs may charge assessment and design fees for a connection offer, accepted or not, and apply them differently. Many give budget estimates free; SSEN doesn't charge to prepare quotes up to 50kW, though connection costs may apply. Check your DNO's charging statement.

Why DNO applications stall

• The wrong DNO or the wrong form. IDNOs typically serve new developments such as business parks, so check the MPAN before choosing a form.
• Missing drawings or authority. No single line diagram, no point of supply marked, or no letter of authority.
• No type test evidence. An inverter that isn't Fully Type Tested needs extra compliance forms.
• Network constraints. SSEN warns that where an area is already stretched, reinforcement is likely and can be very expensive.
• Lapsed offers. Offers expire if not accepted in time, with no guarantee the same terms come back.

Connections and winning commercial work

Once you can handle G99 and export limitation, bigger commercial roofs open up, and the connection becomes part of the pitch: raise it at the survey and make the proposal conditional on the offer. See how to sell commercial solar.

Those surveys have to come from somewhere: see how to get commercial solar leads and solar leads UK: booked surveys, not form fills. Solar Surveys UK books qualified commercial solar survey appointments with business owners for UK installers, paid per booked appointment with no retainer, from £400+VAT to £1,000+VAT per lead by system size (commercial solar lead costs). Browse commercial solar leads.

DNO applications for solar: FAQ

This is a plain-English summary of the official sources below, checked on 7 October 2026, not legal or engineering advice. Rules and timescales change, so confirm with the network operator.