Electricity Connections. Simplified.


Got a question? Check our Frequently Asked Questions first. If you can’t find the answer here,
get in touch.

The Grid

There are three Transmission Owners (TOs) in the UK, National Grid Electricity Transmission (NGET), Scottish Hydro Electric Transmission (SHET), and Scottish Power Transmission (SPT). These TOs own national transmission networks at 400kV/275kV (132kV in Scotland) and transmit power from generation to demand. These networks can be viewed as the motorways of The Grid and are operated by National Grid Electricity System Operator (NGESO).

Below this level there are Distribution Network Operators (DNOs) and Independent Distribution Network Operators (IDNOs) who distribute power at lower voltages, 132kV and below (33kV and below in Scotland) and often supply power to domestic and commercial load.

The Point of Connection (POC) is the location on the existing network where a new connection will be made. Network Operators are mandated to offer the lowest overall cost and best engineering solution.

Point of Supply (POS) is the location on the customer’s site where the metering will be. This metering measures the flow of electrons and calculates a bill based on electricity usage, measured in kWh.

We are able to assist with a range of tasks you need when connecting a project to the grid, examples of these are:

  • Book a surgery with the host DNO/TO to discuss project potential
  • Site capacity review to assess the best location to connect to the grid
  • Prepare and submit an application to the DNO/NGESO to connect
  • Review/appraise/contest/accept the offer
  • Assign an ICP to conduct contestable works
  • Consider using an IDNO to adopt the network assets, further advantages of using an IDNO can be found here.

There are pros and cons for connecting at each voltage relating to network charges and costs of assets. Typically, the larger the connection, the higher the voltage ‘should’ be for an economic and efficient connection.

IDNO Involvement

A firm connection will have more than one route to power the connection which provides greater security of supply in the event of equipment failure.

A non-firm connection does not have an alternative route to power the connection and is therefore more likely to be taken off-supply in the event of a network fault. Therefore it could take longer to get back on supply, although it is a cheaper alternative if security of supply is not as important.

Statement of Works (SoW), also known as transmission impact assessment, is often used as a term to describe the process of assessing a relevant embedded generation project’s impact on the transmission system. These projects must clear this process before being allowed to connect to ‘The Grid’.

There is no official method of speeding up/improving your connection date once offered. However, there are currently reforms being investigated by NGESO that will prioritise projects by ‘readiness to connect’ rather than the traditional ‘first come first served’ queue system that is currently in place. This will, for example, prioritise projects that have met their milestones (planning permission, land rights etc.) over those that haven’t. NGESO are also rewriting the assumptions used when assessing connecting to the grid, which should also speed up connections. Specific workstreams to speed up Battery Energy Storage Systems (BESS)/distribution connections are also being developed.

You do not need to have agreed planning permission by the time you apply for a connection, however you must provide an estimated date that planning permission will be agreed. Attaining planning permission is a contractual milestone.

A few possible constraints are:

  • Upstream network availability (thermal, fault level, reverse power flow etc.)
  • Site location – physical space could be an obstacle for certain connection topologies
  • Active Network Management (ANM)
  • Intertrips
  • Circuit complexity
  • Protection and communication considerations

ANM is a method for DNOs to alleviate capacity constraints by controlling power generation. This avoids the need for costly asset upgrades. Control systems monitor limits on the network and automatically allocate capacity to customers, typically according to the Last In First Out (LIFO) principle where ‘older’ connections are prioritised over recent additions. Connections at the bottom of the stack will be constrained first. ANM details are provided at the network offer stage.

Non-contestable works are works that can only be performed by a licensed DNO/TO. Contestable works can be performed by a DNO/TO AND by a NERS accredited party, this is often an Independent Connection Provider (ICP). An IDNO is able to adopt contestable assets from an ICP once constructed, but not able to adopt non-contestable assets.

Value engineering, flexibility of standards, capital contributions, statutory undertaker powers, metering flexibility – just to name a few. We have prepared a more detailed list of reasons why using an IDNO can be beneficial, click here to view this.


  • You do not need to contribute for pure demand connections, up to £1,720/kVA. If these reinforcement costs exceed this High Cost Cap (HCC), you will be required to pay the difference.
  • You will only pay for reinforcement costs at your connection voltage, these payments are proportional to asset use up to the HCC £200/kW. If the reinforcement costs exceed the HCC, you will (again) be required to pay the difference.


  • ‘Attributable Works’ are works required to connect to the main transmission system. Security is placed against the proportional cost of the asset. Wider works are secured against via a per MW figure calculated in each transmission zone. See here for more details.


For both Distribution and Transmission connections, new sole-use connection/extension assets are fully funded by the connecting party.

  • Capital costs
  • Network charges – Distribution Use of Systems (DUoS) vs Transmission Network Use of Systems (TNUoS)
  • Access rights – security of supply etc.
  • Compliance – different regulatory codes to comply with

The Competition in Connections Code of Practice allows competitive provision for contestable works on DNO connections. This allows Independent Connection Providers (ICPs) to deliver the works and Independent Distribution Network Operators (IDNOs) to adopt. There are also elements of contestability at transmission.


When connecting for generation, G98/99 or Grid Code compliance must be maintained to ensure that network resilience is obtained. If applying to transmission, 100% of liabilities must be securitised for demand only, whereas a proportional methodology is used for generation projects, for information on this see our securities explainer here.

G98/G99 forms are required to be completed by the developer for generation assets to ensure suitable protection settings, as well as resilience during network instability, in order to allow these generators to connect to the upstream network. These protect the assets from upstream faults, as well as protecting upstream network from generation-related faults. EPS are able to assist with completing these forms, ensuring a smooth process when applying for generation projects.


G98 forms are to be completed when you are connecting generators up to 16A (3.86kW) per phase, G99 forms are to be completed when connecting ‘large scale generation’ above 16A (3,86kW) per phase or energy storage. G100 is the standard governing export limitation, where a reduced amount of generated energy is to be exported to the wider network, meaning all embedded generation is to be used on the existing site.

Large embedded generators must contract directly with NGESO via one of the following mechanisms:

  • Bilateral Embedded Generator Agreement (BEGA)
  • Bilateral Embedded Licence exemptible Large power station Agreement (BELLA) – Scotland only


A generator that is small or medium may also submit a BEGA to participate in the national Balancing Mechanism – this ensures supply matches demand in GB. The customer and DNO submit directly to NGESO and receive an offer within 90 days, with 90 days to accept.

Large embedded generators are connected to DNO/IDNO systems with the following sizes: > 100 MW in England & Wales; > 30 MW in South Scotland; > 10 MW in North Scotland.