Grid Acronym Cheat Sheet

As the UK’s electricity network undergoes considerable reform at an unprecedented pace, staying abreast of the ever-increasing acronyms used to reference organisations, policies and technologies can be challenging. 

Scottish Renewables has pulled together a list of network acronyms, from the most commonly used to the more niche, to help you navigate the maze of abbreviations. For a more comprehensive list of all renewable acronyms, please see our original Acronym Cheat Sheet. 

AI - Anticipatory Investment
In the context of electricity networks, AI refers to investment made on behalf of a future user of the same network infrastructure. It most commonly refers to use in offshore networks whereby a lead developer undertakes AI for a shared offshore infrastructure hub that subsequent developers can connect to and benefit from at a later date. 

ALF - Annual Load Factor
Load factor is calculated by dividing the average electricity usage by the peak load within a specific time period where load refers to the rate of electricity consumption in megawatt-hours (MWh). Annual load represents the average usage over a year and is used to calculate projects Transmission Network Use of Service (TNUoS) charges. 

AR - Allocation Round
As part of the Contracts for Difference (CfD) scheme, annual auctions are held into which project developers bid based on their £/MWh costs. Each auction has a maximum £/MWh price and have set eligibility requirements that projects must meet to be able to bid, e.g., having secured a connection date from the ESO. Setting an appropriate budget and £/MWh price with price mechanisms that reflect wider issues is key to enabling more costly, offshore wind projects to be competitive and secure funding. 

ASA - Ancillary Services Agreement
Ancillary Services are additional services that licensed generators provide to the ESO to help maintain a reliable and balanced system. Services can include addressing imbalances between supply and demand, recovering the system after a power system event (e.g., black start) or maintaining correct flow of electricity. As the UK electricity system is fuelled increasingly by renewable energy, there is increased variability and uncertainty on the network and thus, an increased need for ancillary services to stabilise the network. 

ASC - Authorised Supply Capacity
ASC is an agreed amount of electricity that is always made available for a certain project supply by the DNO/TO. The ASC is determined when a new project’s supply is connected to the network, or for upgrades/downgrades of supply and is charged monthly whether or not the full amount reserved is used. 

ASTI - Accelerated Strategic Transmission Investment
The ASTI framework was introduced by Ofgem to fast-track the delivery of 26 strategic transmission projects via a streamlined approval and funding process. The chosen projects represent £20 billion in investment and are intended to help deliver 50GW of offshore wind by 2030. The first project received its provisional funding in March 2024. 

BCA - Bilateral Connection Agreement
A BCA is required of any direct connection to the Transmission system and outlines requirements and liabilities as outlined under codes for both parties for a site-specific project.  

BEGA - Bilateral Embedded Generation Agreement
A BEGA allows embedded generators to connect directly to the transmission network through the ESO and provides them with Transmission Entry Capacity (TEC) and the ability to participate in the Balancing Mechanism (BM). A BEGA is mandatory for a ‘large’ project: anything over 30MW in Southern Scotland or 10MW in Northern Scotland (over 100MW in England and Wales). Any developer with a BEGA is also liable to pay TNUoS charges and adhere to the Connection and Use of System Code (CUSC) and BM.

BELLA - Bilateral Embedded Licence Exemptable Large Power Station Agreement
BELLAs were developed as a quasi-alternative to BEGAs that are less commercially and contractually cumbersome. While they do not offer Transmission Entry Capacity (TEC), BELLAs can be an easier route for smaller developers for whom the regulation associated with BEGAs could be overly demanding.

BESS - Battery Energy Storage System
A BESS captures excess energy from renewable (and non-renewable) power sources during peak times and stores it in batteries to be released onto the network at a later time when needed.

Beyond 2030 - The network build out recommended by the ESO to reach climate goals, otherwise known as tCSNP.
The plan, developed by the ESO, sets out the new and upgraded network requirements to connect an additional 21GW of offshore wind, relying on £58 billion of investment. The plan builds upon the Holistic Network Design (HND) and the Holistic Network Design Follow Up Exercise (HNDFUE) and is undergoing a detailed design phase to produce the final Centralised Strategic Network Plan CSNP in 2026.

BM - Balancing Mechanism
The BM is the main tool used by the ESO to balance supply and demand on the electricity network. Electricity is traded every second to balance the system in the real time over half hourly settlement periods.

BMU - Balancing Mechanism Unit
BMUs are the registered generators connected to the grid that trade under the Balancing Settlement Code (BSC), e.g., a wind farm or power station. A BMU is the minimum amount of equipment that can be metered so, a single generator could be made up of several BMUs. The BMUs are registered in the BM to allow the ESO to balance supply and demand by forecasting changes and subsequently accepting bids from BMUs to manage their generation at a given time. Non-BM units are smaller generators that cannot be as flexible with their output for the BM timescales. 

BSC - Balancing Settlement Code
The BSC is a multi-party contract that sets out the governance and regulation for participation in the Balancing Mechanism (BM), including the framework for submitting bids to trade. 

BSUoS - Balancing Services Use of System
BSUoS charges recover the cost of the day-to-day operation of balancing electricity supply and are paid by final demand site customers, i.e., suppliers and directly connected transmission demand (not including distribution or embedded generators).

CAP - Connections Action Plan
The CAP was published in November 2023 by Ofgem and the UK government and outlines six focus areas to accelerate network connections in the UK, moving from a ‘first come, first served’ to a ‘first ready, first served’ delivery system. The plan builds on the recommendations from the Winser report and aims to reduce connection delays from five years to six months. 

CapEx - Capital Expenditure
A company’s total expenses made on acquiring or upgrading physical or fixed assets, often used for new projects.

CATO - Competitively Appointed Transmission Owner
At present in Scotland, there is a monopoly held between Scottish and Southern Electricity Networks (SSEN) and Scottish Power Energy Networks (SPEN) on transmission electricity networks. To invite new competition to the market with the intent of reducing build times and costs for consumers, the CATO regime was legalised in the Energy Act 2023 for future implementation. CATOs are expected to deliver sections of the ‘Beyond 2030’ network upgrades and the full set of regulations for their operation alongside incumbent TOs is under development by Ofgem. 

CBA - Cost Benefit Analysis
An assessment made to weigh the potential benefits of a decision against the costs associated with it.

CDB - Connections Delivery Board
The CDB is an expert advisory group made up of industry professionals from a range of technology types and oversees connections reform actions, specifically the Connections Action Plan (CAP). The CDB provides strategic direction via guidance around policy and process design, as well as monitoring progress against key milestones. The board releases minutes from their monthly meetings. 

CEC - Connection Entry Capacity
Alongside Transmission Entry Capacity (TEC), CEC is included in transmission offers and is the maximum potential output of a generator onto the National Electricity Transmission System (NETS) and often higher than TEC.  

CES - Crown Estate Scotland
See TCE.

CfD - Contracts for Difference
CfD is a scheme whereby renewable energy developers are paid a guaranteed, fixed rate (known as a strike price) for their electricity over a fifteen-year period by the government-owned company, Low Carbon Contracts Company (LCCC). The UK government scheme was introduced in 2014 to support renewable energy development by covering high upfront costs and de-risking long lifetime projects from wholesale price fluctuations. The scheme’s auction process also protects consumers by ensuring projects are developed at low cost.

CM - Capacity Market
As part of the government’s Electricity Market Reform, the CM aims to support a greater security of electricity supply by providing additional payments to reliable sources of electricity alongside their revenue. Developers can bid into a CM auction and are subject to a ‘de-rating’ factor depending on the reliability of their technology, e.g., solar is subject to a factor of 90% due to its intermittent nature, whereby 1GW would be viewed as 100MW in the CM. The auctions are set with a target total capacity in mind for delivery in T-1 or T-4 years, depending on the auction. Projects that gain capacity agreements are known as Capacity Market Units and are called upon during Triads to demonstrate their ability to provide capacity. 

CNDM - Connections Network Design Methodology
CNDM is the proposed process by which the ESO and TOs will assess connection applications and define the roles and responsibilities of the ESO and TOs in conducting these activities.

CPA - Construction Planning Assumption
CPAs are used as a baseline estimate to model the network upgrade works required to support the connection to and/or use of the network for a new user depending on their predicted input onto the network. As such, CPAs inherently inform connection dates for new users and thus, their accuracy is important. 

CPAG - Connections Process Advisory Group
The CPAG reports to the Connections Delivery Board (CDB) and is the first point of call for testing additional recommendations for future changes around connections. The CPAG specifically helps guide the ESO in its development of detailed designs for changes to the connections process.

(T)CSNP - (Transitional) Centralised Strategic Network Plan
See Beyond 2030.

CUSC - Connection and Use of System Code
The CUSC is the contractual framework for connecting to and using the electricity network in the UK, overseen by the ESO. Any code modifications submitted to the CUSC must be reviewed by the CUSC modifications Panel, or by Ofgem. 

DCUSA - Distribution Connection and Use of System Agreement
The DCUSA is a multi-party contract around the arrangements for connecting to the distribution networks, including charging. All licensed electricity distributors, generators and suppliers are obliged to be signatories to the DCUSA. The agreement connects distributors and suppliers with a service provider for code administration services.

DFTC - Distribution Forecasted Transmission Capacity
DFTC is a newly introduced concept to tie in the work of DNOs with the enduring Connections Reform. Under the DFTC, the DNOs would submit a forecast of works to the ESO by Grid Supply Point (GSP) and technology type, which would act in a similar way to the proposed gate 1 stage of the TMO4+ for transmission projects. The details of the DFTC are being worked through Target Model Option 4+ (TMO4+) Connection and Use of System Code (CUSC) modification working groups. 

DND - Detailed Network Design
Following the publication of the Beyond 2030 network report, the incumbent TOs are working with the ESO to develop the DND, which elaborates on the specific recommendations of the plan. Possible designs are tested through various options, cable routes, technology types and community consultation to determine the optimal final design.

DNO - Distribution Network Operator
DNOs are licensed companies that own and operate the distribution network, i.e., the network that delivers electricity from the transmission network to end-users, such as businesses and homes. 

DRC - Data Registration Code
The DRC details all the data required from a developer by the ESO/TO during the connections process.

DSI - Data Sharing Infrastructure
In January 2024, the ESO officially committed to developing an energy system DSI to advance the network’s digitalisation and smart regulation as well as operational and efficiency to support overall network development. Ofgem have the aim of delivering a functional DSI by 2028 through planned investment and strategy including appropriate incentivisation. 

ECF - Early Construction Funding
A feature of the Accelerated Strategic Transmission Investment (ASTI) scheme, ECF provides project funding of up to 20% for certain activities before planning permission is secured. The aim of ECF is to expedite project delivery where TOs can evidence early funding would facilitate meeting delivery dates. Ofgem reviews all project costs once planning application has been submitted. Within the ASTI decision, there is the suggestion that Ofgem could look to raise the allowance beyond 20% in exceptional circumstances via a ‘re-opener’ in summer 2024 to account for macro-economic factors including supply chain constraints influencing levels of up-front investment. 

EMF - Electromagentic Field
EMFs are made up of electric and magnetic fields that are emitted by various electrical equipment, including household appliances such as washing machines and pylons. Government guidelines stipulate EMFs should not produce more than 9 kV/m for electric fields and 360 microteslas for magnetic fields, which all types of network infrastructure safely abide by. 

ENA - Energy Networks Association
The ENA is a trade body specifically for the companies operating the UK’s gas and electricity network.

ESO - Electricity Systems Operator
The ESO manages the flow of electricity throughout the UK constantly to meet demand and generation where it is needed and maintain a perfect balance between the two. The ESO also provides recommendations to the government and Ofgem, by whom it is regulated, around network changes required to meet energy and climate targets. 

ETDP - Electricity Transmission Design Principles
In the Winser report, the need to create a public document outlining common design principles and methodologies for transmission assets was highlighted. The document would foster best practice sharing and innovation, as well as greater transparency for communities and other stakeholders around the motivations behind decisions around asset development. Design standardisation could also help accelerate route design through automation. The ESO, Ofgem and devolved governments are to work with TOs on this piece going forward via a new working group. 

ETYS - Electricity Ten Year Statement
To inform more strategic planning and future investment, the ESO released a ETYS in mid-2023 that highlighted the future transmission requirements for the next ten years. Drawing upon the ESO’s Future Energy Scenarios (FES), the ETYS feeds into the TCSNP/Beyond 2030 plans that industry stakeholders are consulted on.

FES - Future Energy Scenario
FESs are four different scenarios generated by the ESO that detail different hypothetical but credible pathways to reaching net-zero by 2050. The FES forecasts the amount of energy required and where this demand could be met. The scenarios range from ‘Leading the Way’, representing the fastest credible decarbonisation, to ‘Steady Progression’ representing the slowest via different methods. FES scenarios help inform investment and reform required to realistically achieve the optimal scenarios. 

FID - Final Investment Decision
The point at which a company commits significant financial investment to a project’s development, often taking the project from planning and design into implementation. FIDs are often taken simultaneous to legal requirements and thus are a critical moment for project developers.   

FON - Final Operational Notification
This is issued by the ESO to new generation connections for energisation and first export onto the grid via their connection once they are compliant with all specifications and requirements. 

FSNR - Future Systems and Network Regulation
In March 2023, Ofgem sought views on a framework to reform the electricity and gas network regulation considering the government’s incoming, strategic ‘system plans’, specifically relating to the upcoming price controls of 2026. The insights from the FSNR have subsequently fed into the Revenues + Incentive + Innovation = Output Regulatory Framework-3 (RIIO-3) methodology that has also been consulted on.

FSO - Future Systems Operator
The former name of the National Energy System Operator (NESO), occasionally referred to in past decision papers but that is no longer current.

GEMA - Gas and Electricity Markets Authority 
GEMA is the official governing body for Ofgem made up of a board of members appointed by the Secretary of State at the Department for Energy Security & Net Zero (DESNZ). GEMA’s responsibilities are set out in various energy Acts and these are to set Ofgem’s strategy, policy priorities and take regulatory decisions, including for price controls. 

GIGA - Green Industries Growth Accelerator
The UK government’s newly created fund, announced in late 2023, to support clean energy supply chains by fast-tracking the development of manufacturing capacity. The fund now stands at £1.1 billion supports carbon capture technologies, offshore wind and electricity networks, and civil nuclear.

GSP - Grid Supply Plant
A GSP is the point and substation at which the transmission system connects to the distribution system. Each distribution system is thus referred to as a GSP Group.

HND - Holistic Network Design
The HND, otherwise known as the Pathway to 2030 HND, forms the initial design for strategic network build out that the HND Follow Up Exercise (HNDFUE) and Beyond 2030 have subsequently built upon. Published in July 2022, the HND outlined the offshore and onshore design to facilitate connecting 23GW of offshore wind by 2030 and to support the government’s 50GW by 2050 target. To determine the optimal design, the ESO considered the network design objectives of: cost to consumer; deliverability and operability; impact on environment; and impact on local communities.  

HNDFUE - Holistic Network Design Follow-Up Exercise
The HNDFUE was published in August 2023 and builds on top of the HND to integrate further network requirements, as outlined in the Offshore Transmission Network Review (OTNR), to reach 50GW by 2050. The plan provides follow up recommendations to in-scope developers including plans for the Celtic Sea leased projects and offshore wind in Scotland. 

HVAC - High-Voltage Alternating Current
The UK network, like that of the EU, relies on HVAC, which offers benefits such as minimal power loss over long distances. See HVDC.

HVDC - High-Voltage Direct Current
HVDC can carry much higher voltage than HVAC due to its physical nature and is used for subsea cabling, however it is often more expensive than HVAC and must be carefully integrated into the existing UK AC network. 

INTOG - Innovation and Targeted Oil and Gas
INTOG is a Crown Estate Scotland (CES) seabed leasing round for projects that reduce emissions around oil and gas asset operations, initiated to help meet the North Sea Transition Sector Deal targets. The acronym can be split in two as developers can apply for leases for innovation projects (IN) or for offshore wind projects that would provide low carbon electricity directly to oil and gas infrastructure (TOG). 

LAEP - Local Area Energy Plan
LAEPs translate national net-zero energy ambitions into regional actions to decarbonise local energy systems. Local government organisations engage with stakeholders and understand the current local energy system to model future scenarios that subsequently inform actions and decisions at a local level. 

LMP - Locational Marginal Pricing
LMP, also known as nodal pricing, is a type of network charging methodology that effectively creates prices at each node of the transmission system based on location. LMP sends a locational ‘signal’ to incentivise generators to develop close to high sources of demand. SR’s views on LMP can be read in our blog. 

LoA - Letter of Authority
In the context of grid and connections reform, a LoA is a legal document that provides evidence of formal discussions having occurred between a developer and a landowner around the rights allowing for the project construction on the land or evidencing that the developer is the landowner. For the new Target Model Option 4+ (TMO4+) connections process, an LoA must be submitted alongside any application to be considered for a grid connection. 

LOTI - Large Onshore Transmission Investment
As part of the Revenue = Incentives + Innovation + Outputs Regulatory Framework - Transmission 2 (RIIO-T2) price control (running from 2021-2026), Ofgem introduced a mechanism whereby TOs could submit large investment projects (>£100mil) for funding that had not been included in the RIIO-T2 price control, effective from April 2021. The LOTI covered large projects that missed the RIIO-T2 price control due to lack of clarity around their need, scale and cost, avoiding delays in waiting for the next price control round.

LPA - Local Planning Authority
LPAs are the local government bodies that have the legal right to oversee urban planning and development in a certain area. In Scotland, LPAs are referred to simply as the planning authority of which there are 32 and two national park authorities. The planning authorities are responsible for: development planning; development management; and enforcement. 

MITS - Main Interconnected Transmission System
The MITS is the core of the electricity network encompassing all 400kV, 275kV, and 132 kV in Scotland, elements of the onshore transmission system.

MPI - Multi-Purpose Interconnector
MPIs are subsea cables that allow the UK network to connect to neighbouring European countries and trade electricity. Otherwise known as shared or offshore hybrid assets (OHAs), MPIs are increasingly appearing in the offshore wind space to facilitate the clustering of windfarm assets at sea to allow for more efficient connection to shore.

NESO - National Energy System Operator
The NESO is a new, independent body set to go live in summer 2024 leading the strategic network planning for a whole systems approach.

NETS - National Electricity Transmission System

NGET - National Grid Electricity Transmission
NGET is the Transmssion Owner (TO) for England and Wales. 

NOA - Network Options Assessment
The NOA is the former process for analysing which reinforcement projects gain funding in the upcoming year to best support a reliable and efficient network. The NOA methodology uses Cost Benefit Analysis (CBA) and simulations on data provided by the TOs as well as demand forecasts to determine optimal network reinforcements that minimise costs. The TCSNP/Beyond 2030 and Detailed Network Design (DND) plans are replacing the NOA to give a longer-term view of network reinforcements. 

NPS - National Policy Statements
Produced by government, NPSs detail the justification behind specific policy decisions and how they relate to a larger framework of work in a policy area. 

OBZ - Offshore Bidding Zone
OBZs are set geographical areas within the European offshore energy market where the price of electricity fluctuates in response to that of other connected zones. Typically bordering countries, OBZs more efficiently distribute electricity in relation to demand across several markets and rely inherently on international cooperation.

OCSS - Offshore Coordination Support Scheme
The OCSS is a competitive UK government scheme that provides funding to develop coordinated offshore options for transmission infrastructure, from which it hopes to subsequently inform workstreams such as the Offshore Transmission Network Review (OTNR). The scheme’s first grant was awarded in late 2023 to a consortium of developers seeking to coordinate two offshore wind farms. 

ODI - Output Delivery Incentive
In the context of networks, ODIs are typically set by the regulator, Ofgem, to incentivise a certain standard of output, separate to price control deliverables and licence obligations. ODIs can be in the form of rewards or penalties related to service levels and either financial or reputational.

Ofgem - Office of Gas and Electricity Markets
Ofgem is the national, independent energy regulator for gas and electricity markets, responsible for pursuing energy policy objectives set by government. Ofgem’s primary duty is to protect consumers but it has recently been set a statutory net-zero duty to aid the UK’s ambition of net-zero by 2050. 

OFTO - Offshore Transmission Owner
OFTOs operate and maintain radial offshore transmission infrastructure, connecting offshore wind farms to onshore networks. OFTOs were brought in by the OFTO regime in 2011, which aimed to stimulate competition within networks to deliver coordinated infrastructure.

OHA - Offshore Hybrid Asset
The more up to date term for Multi-Purpose Interconnectors (MPIs) (as used by European markets).

OHL - Overhead Line
Term for the most commonly used form of onshore network infrastructure to transmit electricity across long distance, seen in the forms of visible, overland structures, such as pylons.

OLR - Of Last Resort
OLR refers to situations where a company, e.g., a TO or OFTO, can no longer carry out work that it has been contracted to deliver and so an alternative company must come in to recover the process and complete the required works. 

OpEx - Operating Expenditure
OpEx is the ongoing expense from operating an asset day-to-day, recorded on a developer’s profit and loss statement. 

OTNR - Offshore Transmission Network Review
The OTNR was undertaken in 2020 to assess the delivery models for offshore wind farm transmission connections, looking at environmental, social and economic costs in light of the UK’s imminent targets. The review brought together key stakeholders involved in the full process of offshore wind delivery to inform the requirements for transmission infrastructure going forward. 

OWF - Offshore Wind Farm

PA - Project Assessment

PB - Preferred Bidder
Within network competition tendering processes, the PB refers to the final company (bidder) chosen to deliver the competitive works after assessment has been undertaken comparing all bidders.  

PCD - Price Control Deliverables
PCDs refer to the pre-determined outcomes expected of companies during a price control period, e.g., the Revenue = Incentives + Innovation + Outputs Regulatory Framework (RIIO) price controls. PCDs are allocated specific funding and include deadlines for the work outcomes as well as payments (refunds) to customers if these deadlines are missed or not delivered to a set standard. 

PCF - Pre-Construction Funding
Similar to Early Construction Funding (ECF), PCF exists within the Accelerated Strategic Transmission Investment (ASTI) scheme as a mechanism that allows projects to access 2.5% of the total forecast cost of their project to accelerate any pre-construction activities, notably including supporting high quality planning applications.

PT2030 - Pathway to 2030
The PT2030 is a workstream that encompasses network reinforcements within the Holistic Network Design (HND) and the Network Options A refresh, namely those from TCE’s Leasing Round 4 and CES’s ScotWind leasing round. PT2030 is one of four workstreams that arose from the OTNR, the others being MPIs, Early Opportunities and Future Frameworks.

RAB - Regulated Asset Base
RABs are a type of investment structure commonly used for large public infrastructure projects, such as networks, that need private funding. Though an RAB, investments are de-risked as investors receive a guaranteed return for the lifetime of an asset by the government-owned LCCC. 

RAM - Reliability, Availability, Maintainability
RAM is a type of modelling that assesses and predicts the state of an asset (by the listed attributes) at a given time to ensure a high-level of project performance is constantly maintained. 

REMA - Review of Electricity Market Arrangements
As the UK aims to transition to a decarbonised national grid, the government is undertaking a review of its market design to render it more efficient and effective for a more renewables-based system. The decision to undertake REMA was announced in the British Energy Security Strategy in April 2022 and the second round of  consultation around a series of options closed in May 2024.

RESP - Regional Energy Strategic Planner
As part of the recommendations made in the Winser report, the NESO is planning to implement RESPs to coordinate strategic energy planning. RESPs will be a new body to ensure the high-level objectives of the SSEP are translated to the local level of energy network planning and harmonised across different regions, taking into account local input and regional oversight. 

RIG - Regulatory Instructions & Guidance
Ofgem issues RIGs which detail the reporting requirements from DNOs. RIGs request information on factors such as cost and output delivery to allow Ofgem to monitor DNO performance against RIIO price controls.

RIIO - Revenue = Incentives + Innovation + Outputs Regulatory Framework
RIIO is the regulatory, price control framework employed by Ofgem to ensure network operators deliver on their contracted outputs. As the energy network operators in Scotland currently operate in a monopoly, Ofgem uses RIIO to mimic competitive markets that reward timely delivery, innovation and set limits on revenues. The RIIO price control periods are spread across a number of years, with the upcoming period, RIIO-T3, set to run from 2026-2031.  

SAF - Stakeholder Advisory Forum
Employed in various sectors, SAFs are groups typically made up of diverse stakeholders that aim to provide additional and alternative input onto decisions affecting industry. For the energy code reform, Ofgem intends to use SAFs as a mechanism to review code modification applications going forward to apply greater industry perspective to decisions.  

SCG - Strategic Connections Group
The ENA’s SCG aims to improve customers’ overall experience in connecting to the distribution network by designing and proposing solutions to common issues. The group is made up of network company representatives from transmission and distribution, as well as the ESO, Ofgem and UK government. 

SG - Scottish Government

SGT - Super Grid Transformer
SGTs are located along the transmission system at connection points to either increase or decrease electricity voltage. SGTs increase voltage to transmit power efficiently onto the network or decrease voltage as it flows onto the distribution network and to onward supply.

SIDC - Single Intraday Coupling
SIDC is used across European markets to facilitate the constant trading and negotiation of electricity between market operators in the intraday timeframe. The process begins after the Day-Ahead Market and closes an hour before the delivery period begins.  

SoW - Statement of Works
A SoW is a document meant for both the developer (e.g., TO) and customer detailing the scope, cost and timeline of a project and the responsibilities of the two parties involved. The SoW aims to set expectations from the outset and includes mechanisms for any conflict resolution or changes that may arise within the project.

SPEN - Scottish Power Energy Networks
SPEN is the distribution and transmission network owner and operator for the whole of central and southern Scotland, as well as for stretches of network in England and Wales.

SPV - Special Purpose Vehicle
An SPV is a legal entity that is established for a specific, limited purpose to exist as an independent subsidiary from an umbrella company, often used in competition. OFTOs in the UK are traditionally SPVs that can be owned by multiple investors as a joint venture and resourced by contractors.

SQSS - Security and Quality of Supply Standard
The energy code that determines the methodology for planning and operating the transmission system, to which all TOs must comply with as stipulated in their licence agreements. 

SSEN - Scottish and Southern Electricity Networks
SSEN is the distribution network owner and operator for the whole of northern Scotland and parts of southern England and SSEN Transmission is the transmission network owner and operator for the whole of northern Scotland.

SSEP - Strategic Spatial Energy Plan
As per the Winser report’s recommendations, the UK government is pursuing a national spatial energy plan to inform the future network build out required to meet climate targets. The SSEP will be commissioned to the NESO to develop and should coordinate energy generation with transmission infrastructure to inform the first iteration of the CSNP. The SSEP will identify at a high level where different renewable generation and storage should be located to meet forecast demand and climate targets. 

STC - System Operator Transmission Owner Code
The STC is the code that defines the relationship and the separate roles and responsibilities of the ESO and TOs (including OFTOs).

TAAP - Transmission Acceleration Action Plan
The TAAP was published by the UK government alongside the CAP in late 2023 in response to the Winser report, aiming specifically to halve the end-to-end build time of transmission network infrastructure from 12-14 to seven years through a variety of measures across set themes.

TAG - Transmission Access Guarantee
The TAG is an EU Commission proposal to incentivise investment in OHAs by allowing them to be compensated by TOs when the grid is overly congested and they have to derate, similar to the constraints payment system in the UK.

TCE - The Crown Estate
TCE refers to various areas of land across England, Wales and Northern Ireland that belongs to the British monarch as a corporation sole, translating to public property. TCE is managed by Estate Commissioners who deal with all administrative tasks relating to the land areas. In Scotland, Crown Estate Scotland (CES) exists in the same way since the Scottish estate was devolved in 2017. 

TEC - Transmission Entry Capacity
A project’s TEC refers to the maximum amount of capacity (MW) it requires from and pays to the network to export power on an annual basis, based on an estimation by the project. The TEC is specified at the connection site and is paid in full, regardless of if the power station uses its full capacity within the year. 

TLM - Transmission Loss Multiplier
A TLM is an adjustment applied to a BMU’s metred volumes during a settlement period to account for transmission losses, the cost of which is shared between generators and demand users.

TMO4+ - Target Model Option 4+
TMO4+ refers to the ESO’s package of enduring connection reform, to be applied to new and existing projects as of January 2025. The model’s objective is to resolve the over-burdened connections queue in the UK that is no longer fit for purpose and is delaying viable projects from coming forward.

TNUoS - Transmission Network Use of System
TNUoS charges are paid by project developers to recover TO revenue for the cost of building out and maintaining network infrastructure to different locations. The charges aim to be cost-reflective to influence market behaviour in terms of project location for an economically efficient network, i.e., the further your project is from demand, the more network that is required to be built and thus, the higher charge you pay. 

TO - Transmission Operator
TOs or Transmission System Operators (TSOs) are licensed companies that own and operate the transmission network, i.e., the network that transports electricity across long swathes of the country at a high voltage. In Scotland, SSE and SPEN currently have a monopoly over transmission networks.

TOCO - Transmission Operator Connection Offer
A TOCO is simply the connection offer given to a connection applicant by the TO (via the ESO) and includes design, costs and a programme of works for that specific connection. 

TWR - Transmission Works Register
The TWR forms part of the ESO’s five-point plan for network reform and is based on revised CPAs that should reveal which transmission works are no longer necessary and thus, expedite project connection dates. This process is now coordinating with the Beyond 2030 plan to remove any overlap in proposed works on OHLs.

UGC - Underground Cable
UGCs are an alternative to OHLs that can sometimes be used for short distances under 20km. While UGCs pose less of a visual impact on the landscape, they are significantly more costly than OHL and have a much larger environmental impact due to the excavation required for their construction. 

XBID - Cross-Border Intraday Project
The XBID project is specific to Europe and intends to create a single intraday market to connect and balance markets as the continent sees more intermittent, renewable generation.  

Distribution: lower-voltage cables which carry electricity to homes and businesses.

Transmission: high-voltage cables which carry electricity long distances.