What is a DNO application, and why do I need one?

DNO is an abbreviation for “Distribution Network Operator”; a DNO is a company licensed by Ofgem to be responsible for the distribution of power from the National Grid to your property. When installing Commercial Solar Panels, a DNO application of one type or another will be required to connect to the National Grid, as explained later in

The UK is divided into 14 “districts”, each with its own MPAN (Meter Point Administration Number) prefix, and is run by one of 6 DNOs as listed below:

MPAN Prefix (Distribution ID)	Area	Operator
10	Eastern England	UK Power Networks
11	East Midlands	National Grid PLC
12	London	UK Power Networks
13	Merseyside & Northern Wales	SP Energy Networks
14	West Midlands	National Grid PLC
15	North Eastern England	Northern Powergrid
16	North Western England	Electricity North West
17	Northern Scotland	Southern & Scottish Energy
18	Southern Scotland	SP Energy Networks
19	South Eastern England	UK Power Networks
20	Southern England	Southern & Scottish Energy
21	Southern Wales	National Grid PLC
22	South Western England	National Grid PLC
23	Yorkshire	Northern Powergrid

MPANs for Electricity explained:

An MPAN is a 21-digit number that uniquely identifies your electricity meter and is divided into two lines of information, as shown in the graphic above.

The top line contains technical codes that help your energy provider and DNO understand how electricity is used and should be charged:

Profile Class: A 2 digit number that divides consumers into 1 of 9 categories based upon consumption and load profile. These consumption patterns monitor patterns in usage to help manage the network and provide better services.

✅ 00: Non-Domestic Customers with peak load usage above 100 kW.

✅ 01: Domestic Unrestricted Customers.

✅ 02: Domestic Economy 7 Customers. E7 customers have cheaper electricity rates at night.

✅ 03: Non-Domestic Unrestricted Customers.

✅ 04: Non-Domestic Economy 7 Customers. E7 customers have cheaper electricity rates at night.

✅ 05: Non-Domestic Maximum Demand Customers with a Peak Load Factor of less than 20%.

✅ 06: Non-Domestic Maximum Demand Customers with a Peak Load Factor between 20% & 30%.

✅ 07: Non-Domestic Maximum Demand Customers with a Peak Load Factor between 30% & 40%.

✅ 08: Non-Domestic Maximum Demand Customers with a Peak Load Factor over 40%.

Meter Time Switch Code:

States how many registers your meter has and what times they operate. If your meter has 2 registers, it will also show what times they operate.

Line Loss Factor:

Describes the expected cost that a DNO charges a supplier for use of their cables and electricity network. It also indicates the potential charges a supplier may face due to loss of energy that occurred during the process of getting the electricity to your meter.

The bottom line contains the primary 13 digits of your MPAN, it identifies which area you are in, a unique number to identify your electricity supply point and a check digit.

✅ Distribution ID: A 2-digit number assigned to each District.

✅ Meter Point ID Number: A unique (per district) 8-digit number that identifies the physical metering point.

✅ Check Digit: 3 digits that validate the previous ones through a formula to prevent errors during data entry or supplier transfers.

G98 vs G99

If your inverter’s AC output is no more than 3.68kW (16 Amps) per phase (Allowing up to 11.04kW of output for a 3 phase property), you can have your inverter connected to the grid and submit a completed G98 DNO application within 28 days of your system being commissioned. This is commonly referred to as a “connect and notify system”, is free of charges, and approval can take up to 8 weeks.

A G99 application can cost £300-750 and is required when this limit would be exceeded. Until you receive approval, the system either cannot be connected to the grid, or the inverters’ output will need to be restricted to 3.68 kW per phase. Approval for a G99 application can take anywhere between 10 & 45 working days, depending on the complexity of the application as is usually best handled by an experienced provider, such as Excel Energy UK.

Creating an income stream from surplus Selling Energy

✅ Whether your commercial solar PV installation falls under G98 or G99, every electricity meter in the country has an import MPAN. If you also want to be able to export energy to the grid, you will need an Export MPAN too. This cannot be issued until your G98 or G99 application is approved. Additionally, it is required to sign up for an export tariff, which will enable you to earn money back from the sale of excess energy generated.

✅ Assuming constant values for this vastly simplified example:

✅ If your system were to be generating 10kWh, but your consumption was only 7kWh, your system will then sell the additional 3kWh back to the grid at an already agreed rate.

✅ If this rate was set at 10 pence per kilowatt, then not only has your solar system covered your on-site consumption and saving the cost of importing energy from the grid, but it’s also generated your business 30 pence, which is typically applied as a credit on your bill.

The outcomes of a DNO application

After your DNO application has been received and assessed, the Distribution Network Operator can either accept your system connection as is, reject the proposed installation (though outright rejections are extremely rare), or they will impose what is known as “export limitation” In the first and third cases, you will be sent a connection offer. This includes the maximum specification of the connection and whether there will be any connection charges.

Further details of these outcomes are listed below:

1: Your application is accepted

and your DNO is happy with the size of the system you have requested to install. This means you can proceed with your installation, with no extra charges or amendments.

2: Your application was rejected

and the DNO will not allow your equipment to connect to the grid. But categorical rejections are rare and it is more likely that some additional works are required to be performed to either limit the AC output of the inverter or you will need to pay to upgrade some of the local infrastructure, as seen in points 3a and 3b:

3a. The system size is capped at a given kWp AC rating, and an export limitation is required, (detailed below). Sometimes, a small fee is charged for a witness test, where your provider ensures a limitation has been put in place to protect the local infrastructure.

3b. Your supply size needs to be upgraded from a single phase to a three-phase system to go ahead with your solar panel installation. This additional charge can be pricey depending on the works required.

Export limitation is applied through a 3rd type of application called a “G100”, which costs an additional £300-750 and is typically achieved through fitting an export limitation device to an inverter’s AC output, though a majority of modern inverters also have this functionality built in.

DNO Applications can seem very daunting and complicated, but with a little help from a trusted renewables supplier such as Excel Energy UK Ltd, this process can mostly be handled for you, with only a little information required from you. Contact Excel Energy to start your journey into a greener, more reliable future