Signs of a joined-up approach to speed up storage connections

on 26 April 2023

During the coming months, National Grid Electricity System Operator (ESO) will be introducing measures that will aim to cut connection delays for battery energy storage system (BESS) projects, as part of wider connection reforms.

Following the launch of its five-point plan in February, to accelerate connections to the transmission grid, ESO is implementing a new approach for energy storage within its Construction and Planning Assumptions (CPAs) to align with how developers/owners intend to operate storage assets.

CPAs, which are used to assess and model grid connections, are undergoing adaptation to be made fit for purpose in the face of the surge in grid connection requests, especially for BESS and other distributed energy resources (DERs), such as solar projects and EV charging infrastructure.

National Grid’s BESS modelling has tended towards the conservative, but following extensive feedback from developers, it is clear to ESO that these assets can be operated so they do not correlate with times of constraint on the network.

Implementing interim option for connecting BESS assets sooner

This has paved the way for National Grid to introduce a new type of “interim non-firm connection”, which distribution system operators (DSOs) are also introducing on their regional MV grids.

These interim connection options are initially for storage projects enabling these to connect to the network sooner if they meet requirements to turn off more frequently when needed to, without initially being paid. Essentially ESO will have the ability to instruct BESS assets to operate at 0MW to prevent them contributing to grid constraints.

The conditions of curtailment will be stipulated in a customer contract, between National Grid and developers, allowing a BESS developer to carry out its own risk assessment of frequency and timing of constraints, while ESO will also provide additional information to help developers with their risk assessments.

The intention to facilitate connections for storage ahead of enabling grid works, such as new substations or overhead lines, provided that visibility and control facilities are installed to allow ESO to control these assets when required.

ESO, Network Owners and the industry are working across activities for interim non-firm connections to be implemented soon, including:

Network Owners/ESO Connections

  • Improving modelling of energy storage
  • Understanding of implications of curtailment on service provision
  • Defining contractual terms for non-firm connections and associated network restrictions
  • Establish data to be provided to energy storage to enable calculation of curtailment risk
  • Undertaking assessments to determine works for firm connections

ESO-Electricity Network Control

  • Processes established to ascertain when and how energy storage can be curtailed.
  • Establishing optimum time (Day Ahead/ within day) for providing curtailment signals
  • Development of IT systems to issue instructions to energy storage at both transmission and distribution.
  • Systems to establish when curtailments are compensated versus not compensated.

Storage Developers

  • Carry out assessment of risk of curtailment frequency and duration of curtailment.
  • Understand implications of curtailment on service provision.
  • Work with Network Owners/ESO to sign up to appropriate systems to receive curtailment instructions.
  • Enact upon instructions in appropriate timescales.

(credit: National Grid ESO)

North-east suffering significant grid constraint

To meet the government’s net zero target, the GB grid must deliver more than five times the amount of electricity transmission infrastructure in the next seven years, than has been built in the past 30 years, according to National Grid.

Much of this expansion and upgrade is needed in north-east England, to increase flows of generation to big demand centres in the south. In the meantime, grid constraints in the region are a growing issue.

During a recent webinar on the subject of facilitating connections in northern England, which included presentations from National Grid (ESO and NGET) and Northern Powergrid, NGET slides indicated that 35% of National Grid Electricity Transmission (NGET) customers facing a connection delay of more than one year, with BESS projects take 2-4 years.

Cambridge Power’s experience is of much more significant delays, with new BESS connections facing delays of at least seven years, so well into the next decade, even 2035.

NGET at least acknowledges that without “fundamental reform” the queue will continue to rise rapidly, due to growth in BESS demand, possible relaxation of onshore planning restrictions and an increase in EV/heat pump adoption.

In north-east England, where constraint issues are most acute, National Grid is working on similar approaches that have been implemented further south with DSOs such as UKPN, including Regional Development Programmes, specifically MW dispatch projects.

In the coming weeks National Grid has confirmed that it will roll out whole system solutions – coordinated across T&D – that facilitate non-firm connections, according to ESO’s Andrew Wainwright, Head of Whole Electricity System, during the webinar.

DSO Northern Powergrid has 120 customers experiencing long lead times for connections for exporting to the transmission system, mainly impacting exporting assets, spanning generation and also storage projects.

Increased collaboration

During the webinar Jim Cardwell, Head of DSO Policy, Northern Powergrids, said there has been collaboration, among the Energy Networks Association, as well as between transmission and distribution companies, to alleviate connection delays.

The first is queue optimisation. This entails exercising contractual rights to remove stalled projects from the queue and free up capacity for projects that can proceed.

The utility is also seeking the ability to refer fewer decisions to the ESO by obtaining delegated authority.

It is also stepping up efforts to facilitate sharing of more information between customers and the utility to accelerate connections around BESS, for example obtaining more information on BESS profiles will help it make quicker connection decisions.

Northern Powergrid is also making available “heat maps” to help customers make better decisions about how and where to connect on the grid, publishing project progression summaries and providing more opportunities for customer engagement.

These developments, while welcome, are long overdue. Many European DSOs regard the UK as one of the more advanced markets, citing UKPN’s 500MW flexibility tender in late 2022 as an example. The reality is that without there being a standardised approach, backed by strong, clear policy and regulation, some parts of the GB power network will continue to lag.

In its revamped Net Zero strategy, published on 30 March, the Government chose to put its faith in unproven or costly technologies like carbon capture and storage (CCS), while omitting energy storage and continuing to ignore the fact that the UK’s ageing electricity network is not fit for purpose. The acute symptoms are the years-long grid connection delays for BESS and other DERs, with certain regions, such as the north-east in dire need of investment and transformation to fully accommodate and effectively distribute the planned huge volumes of clean energy – offshore wind – over the next decade and beyond.