Reference is made to the Balancing and Settlement Code for the Electricity Industry in Great Britain and in particular, BSC Sections S and Annex S-2.
This is the On-Site Energy Allocation Methodology Document, Version 1.0.

3. This BSC Code Subsidiary Document is effective from 02 November 2023.

4. This BSC Code Subsidiary Document has been approved by the BSC Panel or its relevant delegated Panel Committee(s).

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Amendment Record

Version	Date	Description of Change	Changes Included	Mods/Panel/Committee Refs.
1.0	02/11/2023	02 November 2023 Standard Release	P395	P343/06

1 Introduction

1.1 Purpose and Scope of the Code Subsidiary Document

The purpose of this Balancing and Settlement Code (BSC) Category 3 Code Subsidiary Document is to specify the method by which Imports at Boundary Points subject to an EMR AMSID Declaration are allocated to different classes of on-site user (Licensed Storage, Licensed Generation, Other), and hence deemed to be chargeable or non-chargeable (for purposes of the CFD and CM charges levied on Licensed Suppliers).

1.2 Main Users of Procedure and their Responsibilities

This methodology document specifies the calculations performed bv the Supplier Volume Allocation Agent (SVAA) in order to determine the proportion of Boundary Point Imports to the Import Metering Systems included in an EMR AMSID Declaration “D” that should be deemed non-chargeable in each Settlement Period. It can also be used by any Supplier that has submitted, or intends to submit, an EMR AMSID Declaration to the SVA Agent (SVAA) in accordance with BSCP602, that wishes to better understand how the reduction in its chargeable Demand will be calculated by the SVAA.

1.3 Use of the Procedure

The remaining sections in this document are:

Section 2 -.Describes why this document is required.

Section 3 –Sets out an overview of the Methodology, including details of the required Inputs and Outputs.

Section 4 –Sets out the detail of the agreed Methodology.

Section 5 – Sets out the process for changing the Methodology.

1.4 Balancing and Settlement Code Provision

This BSC Code Subsidiary Document has been produced in accordance with the provisions of the BSC. In the event of an inconsistency between the provisions of this document and the BSC, the provisions of the BSC shall prevail.

1.5 Associated BSC Procedures

BSCP602

SVA Metering System & Asset Metering System Register

1.6 Acronyms and Definitions

1.6.1 Acronyms

The terms used in this BSC Code Subsidiary Document are defined as follows.

AMSID	Asset Metering System Identifier
BSC	Balancing and Settlement Code
BSCP	BSC Procedure
CfD	Contracts for Difference
CM	Capacity Market
SVAA	Supplier Volume Allocation Agent

1.6.2 Definitions

Full definitions of the above acronyms are, where appropriate, included in the BSC.

2 Why is an On-Site Energy Allocation Methodology Document required?

An EMR AMSID Declaration provides a mechanism for Suppliers to notify SVAA where Asset Metering is being used to measure power flows to/from Licensed Generation and/or Storage that shares a Boundary Point with Final Demand. Imports to the Licensed Generation and Storage will continue to be treated as subject to CFD and CM charges, unless Asset Metering is installed to provide Settlement with details of power flowing to and from the licensed assets.

However, installing Asset Metering does not in itself solve the problem of identifying which Imports should be treated as chargeable. For example, consider a site with Final Demand, Licensed Generation and Licensed Storage, such as this:

In this example, the Boundary Point meters show that there were 20 MWh of Import to the site. But the half hourly metered data available to settlement cannot show where that Import went. For example, did the 10 MWh of Import to the Licensed Storage come from the Boundary Point, or from the Licensed Generation?

The P395 Workgroup acknowledged that, in principle, it might be possible to shed light on these questions with access to more granular (moment-by-moment) metering data and/or the details of the contractual relationships between the parties on site (e.g. who is deemed to be purchasing power from whom). But this would require complex investigations on a site-by-site basis, which would be disproportionately expensive and difficult. The agreed solution for BSC Modification P395 is therefore that a methodology is required that specifies appropriate rules for using the Asset Meter data to deem where the Boundary Point Imports were used, and therefore the extent to which they are chargeable.

The approach agreed by the P395 is a ‘merit order’ approach, that allocates energy on a predefined ‘merit order’ approach. For example, it assumes that:

Export from Licensed Generation is first used to charge Licensed Storage, then used elsewhere on site, and only then exported to the grid;
Export from Licensed Storage is first exported to the grid, then used by Licensed Generation, and only then used by other on-site users.

3 Overview of the Methodology

3.1 Inputs and Outputs to the Methodology

The Methodology will be implemented in software as a process that takes metered data (for a site subject to an EMR AMSID Declaration), and works out the proportion of Boundary Point Imports (in that half hour) which should be treated as non-chargeable. The inputs to the process are therefore as follows. Note that all inputs are assumed to have been loss-adjusted to a common reference point, so that they are directly comparable with each other:

Input	Formal Name (used in BSC)	Name used in this Document	Value in Example 1
Total site Import (as measured by Boundary Point meters¹)	AMSID Declaration Boundary Point Import (ADBPI_Dj)	IMP^BP	20 MWh
Total site Export (as measured by Boundary Point meters)	AMSID Declaration Boundary Point Export (ADBPE_Dj);	EXP^BP	2 MWh
Total Import to Licensed Storage (as measured by Asset Meters)	AMSID Declaration Storage Import (ADSI_Dj)	IMP^STOR	10 MWh
Total Export to Licensed Storage (as measured by Asset Meters)	AMSID Declaration Storage Export (ADSE_Dj)	EXP^STOR	0 MWh
Total Import to Licensed Generation (as measured by Asset Meters)	AMSID Declaration Generation Import (ADGI_Dj)	IMP^GEN	3 MWh
Total Export to Licensed Generation (as measured by Asset Meters)	AMSID Declaration Generation Export (ADGE_Dj)	EXP^GEN	18 MWh

The output of the calculation is the proportion of the total site Import (IMP^BP) that is deemed to be subject to CFD and CM charges (in this Settlement Period).

3.2 Calculation Overview

The methodology can be summarised as follows:

Step 0: work out the Imports (IMP^OTHER) and Exports (EXP^OTHER) to assets other than Licensed Storage and Generation. In example 1 above there is a net IMP^OTHER = 23 MWh of Import that went to somewhere other than Licensed Generation and Storage. This could be customer demand, or licence exempt storage, or licence exempt generation.
Step 1: use a merit order approach to work out where power is deemed to have flowed within the site. For example, how much of the Import at the Boundary Point was used by Licensed Generation? And how much of the Export from Licensed Storage was exported back across the Boundary Point?
Step 2: use the deemed power flows from step 1 to establish how much of the Boundary Point Import should be treated as chargeable

Section 4 below explains each step in detail.

4 Detail of Required Calculations

4.1 Step 0 – Calculate Imports and Exports for other on-site users

The steps in the calculation are as follows. Note that electrical losses are not explicitly considered, as the SVAA system will already have adjusted the inputs for losses (in order to account for different voltage levels within the site) prior to performing the calculations described in this Methodology:

Acronym	Equation for Calculating	Value in Example	Comment
NET^OTHER =	(IMP^BP – IMP^STOR – IMP^GEN) – (EXP^BP – EXP^STOR – EXP^GEN)	23 MWh	Net Import not accounted for by Asset Metering
IMP^OTHER =	MAX(0, NET^OTHER)	23 MWh	At least one of IMP^OTHER and EXP^Other will always be zero.
EXP^OTHER =	– MIN(0, NET^OTHER)	0 MWh

4.2 Step 1 – Determine Deemed Flows of Power

The following calculations apply the ‘merit order’ methodology to deem how much power flowed between different types of user.

Within this Methodology, the acronym ^user1X_user2 denotes the power that is deemed to have been provided by user1 to user2. For example, ^BPX_OTHER is the Boundary Point Import that was used by non-Licensed (chargeable) users onsite, and ^OTHERX_BP is the electricity generated by those non-Licensed users that was exported back across the Boundary Point.

The agreed calculations to apply the merit order methodology are as follows:

Acronym	Equation for Calculating	Value in Example	Comment
Surplus =	MAX(0, EXP^GEN+EXP^STOR – BP^EXP)	16 MWh	Surplus power produced by licensed activities on-site
^GENX_STOR =	MIN(EXP^GEN, IMP^STOR, Surplus)	10 MWh	Allocate Generation Export to Storage first (capped by the calculated value of Surplus)
Remaining =	Surplus – ^GENX_STOR	6 MWh	Surplus not yet allocated
^GENX_OTHER =	MIN(EXP^GEN – ^GENX_STOR, IMP^OTHER, Remaining)	6 MWh	Allocate Generation Export to other on-site use
^GENX_BP =	EXP^GEN – ^GENX_STOR – ^GENX_OTHER	2 MWh	… And finally to Boundary Point Export
^STORX_BP =	MAX(0, MIN(EXP^BP – ^GENX_BP, EXP^STOR))	0 MWh	Allocate Storage Export to Boundary Point …
^STORX_GEN =	=MAX(0, MIN(IMP^GEN, EXP^STOR – ^STORX_BP))	0 MWh	… and then to Generation …
^STORX_OTHER =	MAX(0, EXP^STOR – ^STORX_BP – ^STORX_GEN)	0 MWh	… and finally to Other.
^BPX_STOR =	MIN(IMP^BP, IMP^STOR – ^GENX_STOR)	0 MWh	Allocate Boundary Point Imports to Storage …
^OTHERX_STOR =	IMP^STOR – ^GENX_STOR – ^BPX_STOR	0 MWh	And remaining Storage Imports from Other
^BPX_GEN =	MIN(IMP^GEN – ^STORX_GEN, IMP^BP – ^BPX_STOR)	3 MWh	Allocate Boundary Point Imports to Generation …
^OTHERX_GEN =	MIN(IMP^OTHER, IMP^GEN – ^STORX_GEN – ^BPX_GEN)	0 MWh	And remaining Generation Imports from Other
^BPX_OTHER =	IMP^BP – ^BPX_STOR – ^BPX_GEN	17 MWh	Any remaining Boundary Point Imports must gone elsewhere on-site
^OTHERX_BP =	EXP^BP – ^GENX_BP – ^STORX_BP	0 MWh	Any remaining Boundary Point Exports must have come from elsewhere on-site

4.3 Step 2 – Determine Proportion of Boundary Point Imports that are Non-Chargeable

At this point, the Boundary Point Imports IMP^BP have been split into three components:

The Imports used by Licensed Generation (^BPX_GEN), which are non-chargeable (for CFD and CM purposes);
The Imports used by other non-licensed activities (^BPX_OTHER), which are chargeable (for CFD and CM purposes); and
The Imports used by Licensed Storage (^BPX_STOR), which may or may not be chargeable, depending on how the stored power is subsequently used.

The Settlement system will not know how a particular unit of electricity stored in the battery is subsequently used, and the Workgroup therefore agreed that the proportion of ^BPX_STOR that is deemed non-chargeable should be calculated based on where storage Export went over a reference period comprising the previous 7 Settlement Days. For each Settlement Day, the Non-Chargeable Storage Proportion is calculated as follows:

Retrieve EXP^STOR and ^STORX_OTHER data for all Settlement Periods in a reference period comprising the previous 7 Settlement Days. The actual number of Settlement Days to use will be a configurable parameter, specified in the Methodology Document and potentially changing from time to time (at the direction of the BSC Panel)
The methodology must allow for the possibility that data will not be available for all Settlement Periods in the reference period (e.g. for a new Declaration). Determine N_Valid as the number of Settlement Periods that do have the required data, and N_Missing as the number that do not.
For the Settlement Periods that do have data, determine the Non-Chargeable Storage Proportion as:

{N C S P}_{V a l i d} = \frac{\sum ({E X P}^{S T O R} - {}^{S T O R}{X_{O T H E R}})}{\sum {E X P}^{S T O R}}

Determine an overall Non-Chargeable Storage Proportion (allowing for Settlement Periods with missing data) as follows:

N C S P = \frac{{N C S P}_{V a l i d} ∙ N_{V a l i d} + {N C S P}_{D e f a u l t} ∙ N_{M i s s i n g}}{N_{V a l i d} + N_{M i s s i n g}}

where NSCP_Default is a default value of the Non-Chargeable Storage Proportion (applied to Storage Facilities without data). It will be set by the BSC Panel from time to time (and could be 0.0, if the BSC Panel believed it appropriate that Imports to Licensed Storage Facilities should be deemed chargeable in the absence of evidence to the contrary).

Having calculated a value of NCSP for this EMR AMSID Declaration on this Settlement Day, SVAA will then calculate the AMSID Declaration Non‑Chargeable Proportion (ADNCP_Dj) for each Settlement Period of the Settlement Day. This represents the proportion of Boundary Point Imports (IMP^BP) in that Settlement Period which should be treated as non-chargeable:

{A D N C P}_{D j} = \frac{{}^{B P}{X_{G E N} +} {}^{B P}{X_{S T O R}} . N C S P}{{I M P}^{B P}}

5 Process for Amending this Methodology Document

For the purposes of BSC Procedure BSCP40 (Change Management) this document is a Category 3 BSC Configurable Item, meaning that it is not subject to the Modification Procedures in Section F (‘Modification Procedures’) of the BSC, or the Change Proposal process described in BSCP40.

Paragraph 3.12.2 of BSC Annex S-2 allows the BSC Panel to review this Methodology Document from time to time, and make such revisions as it considers necessary (but does not require such reviews to be carried out). The Panel has agreed the following process for changes:

It is the BSC Panel’s decision whether to review or change the Methodology, but BSCCo or any Supplier can request them to do so, if there is evidence that a change to the Methodology could materially improve the accuracy of the gross demand reported to EMRS;
The BSC Panel may request assistance from BSCCo e.g. in analysing whether a change is needed;
Unless otherwise agreed by the Panel, changes to the document will be drafted by BSCCo; and
The Panel will consult with Parties in a manner appropriate to the scale and complexity of the changes before agreeing them.

It should be noted that any material change to the Methodology will require changes to Settlement systems, and the BSC Panel would take this into account when agreeing the effective date for any change

1 All metered volumes received from HHDAs and HHDCs are in kWh, so must first be converted to MWh

CONTENTS

On-Site Energy Allocation Methodology Document