Checking which DNO covers a site before you quote a solar job
In short
Great Britain's electricity network is split between six DNO groups, and every site postcode maps to exactly one of them. Use the ENA's free postcode lookup at energynetworks.org to identify the operator before pricing, then build the G98 or G99 timeline into your quote.
- Great Britain has 14 electricity distribution regions operated by six licensed DNO groups, and every site postcode maps to exactly one of them.
- The ENA's free postcode lookup at energynetworks.org identifies the correct DNO in under a minute using only the site postcode.
- Whether a system requires G98 notification or G99 pre-approval depends on the inverter's AC output rating, not the number or total wattage of the panels.
- A G99 application must be approved before installation begins and can take up to 45 business days, so that window belongs in the project programme before you quote.
- Logging the DNO operator and applicable standard in the job record at quote stage means the correct paperwork reaches the right operator when the project converts.
Before pricing any solar or electrical job, confirm which electricity distribution network operator covers the site. The DNO determines your application route, G98 or G99 timeline, and whether a pre-approval window needs to go into your project schedule before your quote goes out.
An electricity distribution network operator (DNO) is the licensed company that owns and maintains the cables, transformers, and substations that carry electricity from the national transmission grid to homes and businesses in a defined geographic area. The DNO is not the same as the customer's electricity supplier. The supplier bills the customer for the energy they consume; the DNO owns the physical infrastructure the electricity travels along, and no customer ever switches their DNO. Great Britain is divided into 14 distribution regions operated by six main DNO groups. To find the right one for a given site, all you need is the site postcode - the Energy Networks Association (ENA) provides a free lookup at energynetworks.org that returns the correct operator in seconds.
For solar and electrical installers, the DNO question is not a paperwork formality. Every system that connects to the grid must be formally registered with the correct operator under G98 or G99 engineering standards. The operator you notify determines the application form to use, the portal to submit through, the timeline to apply to your project schedule, and - for G99 jobs - whether there will be a pre-approval wait before installation can begin. Quote a job before you know the DNO and you are pricing a project whose start date and additional costs you cannot yet confirm.
Why the DNO is not the same as the energy supplier
Many customers confuse the DNO with the energy supplier. Both are involved whenever someone discusses the electricity grid, so the confusion is understandable. The distinction matters because the two organisations serve fundamentally different roles.
The energy supplier sells electricity to the customer, issues bills, and will later pay the customer under the Smart Export Guarantee (SEG) for surplus power exported to the grid. The customer can switch supplier at any time. The DNO owns the distribution infrastructure in its licensed area. The customer has no choice over which DNO serves their site and will never receive a direct bill from them. When a solar PV system connects to the grid, the notification or application goes to the DNO - not to the supplier.
Practically, this means DNO identification is an installer task, not a customer task. The customer will almost certainly not know which operator covers their site, and pointing them to their electricity bill often adds confusion rather than resolving the question. The faster path is for the installer to run the ENA postcode lookup directly at enquiry or survey stage.
The six DNO groups and 14 distribution regions
Great Britain's electricity network is licensed to six DNO groups, split administratively into 14 distribution regions. Knowing the group is usually enough to find the right contact and application portal, but knowing the specific region matters when reading MPAN numbers or working with archived application forms.
The six groups, and the broad areas they serve, are:
- UK Power Networks - South East England, East of England, London
- National Grid Electricity Distribution (formerly Western Power Distribution) - Midlands, South West England, Wales
- Northern Powergrid - North East England, Yorkshire
- Electricity North West - North West England
- Scottish and Southern Electricity Networks (SSEN) - South of England, North of Scotland
- SP Energy Networks (ScottishPower) - Central and Southern Scotland, Merseyside and Cheshire
Northern Ireland sits outside this structure and operates under a separate regime. Solar installers working across multiple regions should treat DNO identification as a standard pre-quote step rather than relying on memory of where regional boundaries fall - those boundaries do not follow county lines.
A note on IDNOs: on some newer housing developments and commercial estates, distribution infrastructure is owned by an Independent Distribution Network Operator (IDNO) rather than one of the six main groups. IDNOs are not tied to geographic regions and are regulated by Ofgem separately. If the ENA lookup returns an IDNO result, the G98 notification or G99 application process is essentially the same - but the contact details and submission portal will differ. The lookup handles both results, so the workflow is consistent.
G98 or G99: what the DNO lookup tells you next
Once you know which operator covers the site, the next question is which Engineering Recommendation governs the connection. The answer determines whether you can install first and notify afterwards, or whether you need formal pre-approval before any installation work begins.
G98 applies to systems at or below 3.68 kW on a single-phase supply, or at or below 11.04 kW on a three-phase supply. These are "fit and inform" installations: the system is commissioned first, then the installer notifies the DNO within 28 days. G98 notifications are free of charge, and the DNO cannot refuse them for compliant, type-tested equipment. For most standard domestic solar installations, G98 is the applicable route.
G99 applies above those thresholds - any single-phase inverter rated above 3.68 kW, or any combined solar-and-battery system where total export capacity exceeds the G98 limit. G99 is a pre-approval process: the application must be submitted and the DNO's Connection Offer received before installation can start. Standard G99 applications take up to 45 business days (approximately nine calendar weeks). Many DNOs process straightforward residential G99 cases in four to eight weeks. A simplified fast-track route is available for qualifying lower-complexity systems, which can reduce the wait to around 10 working days. For commercial assessments where the DNO needs to model local network capacity in detail, 8 to 12 weeks is common.
Adding battery storage can shift a G98 job into G99 territory. If the customer is considering a solar-plus-battery package, confirm the combined inverter output at the design stage before quoting. A 4 kWp panel array paired with a 3.68 kW inverter stays in G98. The same array paired with a 5 kW hybrid inverter moves into G99. Quoting the wrong route - or omitting it entirely - sets up a timeline conversation the quote cannot resolve after it has been accepted.
How to check which DNO covers a site before you quote a solar job
Collect the site postcode and any available meter point details
At enquiry or survey stage, record the full site postcode. If the customer can share a recent electricity bill, note the MPAN (Meter Point Administration Number). The first two digits of the MPAN correspond to a DNO distributor ID and provide a useful cross-check on the postcode lookup result. You do not need the MPAN to identify the operator, but it confirms you have the right one if there is any ambiguity about a site that sits near a regional boundary.
Run the ENA postcode lookup at energynetworks.org
Enter the site postcode into the Energy Networks Association's free lookup tool. The result names the DNO or IDNO, provides contact details, and links to the operator's connections portal. This takes under a minute and should be completed before any system sizing or quote pricing begins. MCS's own guidance for installers directs you to the same ENA tool as the definitive method for determining which operator to notify.
Determine which Engineering Recommendation applies
Using your proposed system design - specifically the inverter AC output rating - check whether G98 or G99 applies. At or below 3.68 kW single-phase (or 11.04 kW three-phase): G98 applies, no waiting period before installation. Above those thresholds, or with battery storage that pushes combined export over the limit: G99 applies, and the application must be submitted and approved before you can start work. Confirm the applicable route before quoting, not after the customer has accepted.
Check that DNO's current application requirements and indicative timelines
Each of the six DNO groups maintains its own connections portal and may have specific form requirements beyond the ENA standard documents. Once you have identified the operator, visit their connections page and note any DNO-specific forms, portal registration steps, and current processing times. Some operators publish indicative queue times that differ from the standard 45-business-day ceiling. A G99 application to a DNO currently running 12-week queues belongs in your project programme before you commit a start date to the customer.
Factor DNO timelines and any potential connection costs into your quote
For G98 jobs, the DNO timeline does not affect your start date. For G99 jobs, build the approval window into your schedule explicitly and make that clear in the quote. Grid reinforcement costs are uncommon for standard domestic systems but occur more frequently on constrained rural networks and on commercial rooftop jobs above 50 kW. State in your quote whether G98 notification or a G99 application is included in your scope, that you are handling submission on the customer's behalf, and that the G99 approval window determines the project start date rather than your diary availability.
Log the DNO details in your job record before sending the quote
Before the quote goes out, record the DNO name, region, contact details, and the applicable Engineering Recommendation in your job record. When the project converts from quote to active job, that information is already in place for whoever submits the paperwork, manages the customer relationship, or schedules the installation. Keeping DNO details attached to the job - rather than in a separate email thread or a site survey PDF that may not travel with the job - prevents the scenario where the notification goes to the wrong operator or the wrong form is submitted. Using Jobs & Orders means the DNO operator, applicable standard, and submission status sit alongside the quote, purchase orders, and installation schedule in one place. Project Tracking lets you set the G99 approval as a milestone the job cannot progress past until the Connection Offer is received.
Submit the G98 notification or G99 application at the correct project stage
For G98 installations: commission the system, then submit G98 Form B to the DNO within 28 days. For G99 installations: submit the application pack before scheduling the installation date, wait for the Connection Offer, accept it, and then confirm the start date with the customer. For integrated solar-and-battery systems that qualify for the G99 fast-track route (Form A1-2), submit before installation but expect a reduced timeline compared to a full G99 assessment. Whichever route applies, retain a copy of the DNO acknowledgement and file it with the MCS certificate - both documents are required for the customer's Smart Export Guarantee registration and for conveyancing documentation when they sell the property.
Common mistakes that cost installers time and margin
Not identifying the DNO before quoting creates three predictable problems. First, if a job requires G99 but the quote assumed a G98 timeline, the customer may refuse to accept a start date weeks later than originally discussed - a conversation that puts the relationship at risk before installation has begun. Second, if a site sits on an IDNO estate rather than the main network, submitting the notification to the nearest standard DNO sends it to the wrong operator. Identifying and correcting that mistake can take several weeks, during which the installation has no valid grid registration. Third, on commercial solar jobs where the system almost always exceeds G98 thresholds, a G99 timeline of 8 to 12 weeks that was not built into the project programme can push commissioning past a financial year-end, a lease start date, or a tenant move-in date.
All three problems are avoided by running the ENA postcode lookup and confirming the applicable Engineering Recommendation before the quote is drafted. The DNO check takes under five minutes at enquiry stage. Correcting a misidentification after a quote is accepted can take months.
For a full view of how solar installers manage the quote-to-commission workflow - including MCS documentation, G98 and G99 notifications, and stage invoicing - see the Renewables & Solar section of the Zigaflow site.
Sources
- DNO Application for Solar UK: G98 vs G99Smart Solar Homes · accessed 2026-10-09
- Notifying DNOsMCS Certified · accessed 2026-10-09
- Grid Connection and DNO Applications (G98/G99) ExplainedThe Solar Co · accessed 2026-10-09