Show me the money: settlement and markets
By the end of this module you will be able to:
- Trace the settlement chain from generators through BM, SVAA, SAA, and FAA to the consumer bill
- Explain SBP/SSP price asymmetry and how MHHS reduces credit cover requirements by 71%
- Break down a consumer bill into its components: wholesale (~45%), network (~27%), policy (~13%), operating (~10%), and VAT (5%)
Think about it
Every megawatt-hour generated must be paid for by the megawatt-hour consumed. Settlement makes sure the money goes to the right place.
Module 6 traced a single reading through the data lifecycle. This module zooms out to the entire settlement system: the chain of agents, calculations, and cash flows that convert physical electricity into financial transactions. We follow the data from generator dispatch through balancing, allocation, imbalance pricing, and reconciliation, then examine how the wholesale market structure drives the prices that ultimately appear on consumer bills.
Settlement is where data quality has the most direct financial consequence. An error in a meter reading changes an imbalance calculation, which changes a cash flow, which changes a supplier's costs, which changes a consumer's bill. Every number matters.
At 07:00 this morning, a gas-fired power station in Kent injected 450 MW into the transmission network. At the same moment, 28 million households were turning on kettles, lights, and heaters. A wind farm in Scotland was producing 200 MW less than forecast because the wind dropped overnight. Somewhere in this chaos, a mechanism must determine who owes whom, how much, and when. That mechanism is electricity settlement, and it runs on data — half-hourly meter readings, generator notifications, bid-offer acceptances, and imbalance calculations that settle billions of pounds every year.
With the learning outcomes established, this module begins by examining from generator to balancing mechanism in depth.
10.1 From generator to Balancing Mechanism
Settlement starts before the electricity is even generated. Every large generator connected to the transmission network must submit Physical Notifications (PNs) to the National Energy System Operator (NESO) before each half-hourly settlement period. A PN states how much power the generator expects to produce, typically based on their forward contract position and plant availability.
Final Physical Notifications
PNs are refined as the settlement period approaches. The Final Physical Notification (FPN) is the generator's last declaration of expected output, submitted at gate closure (one hour before the settlement period). The FPN is the baseline against which any balancing actions are measured. If a generator produces exactly its FPN, it has no balancing exposure. If it produces more or less, the difference is settled through the imbalance mechanism.
Bid-Offer pairs
Alongside their FPN, generators submit Bid-Offer pairs to the Balancing Mechanism (BM). An Offer is a price at which the generator is willing to increase output above its FPN. A Bid is a price at which the generator is willing to decrease output below its FPN. NESO uses these Bids and Offers to balance supply and demand in real time.
When demand exceeds supply, NESO accepts Offers (instructing generators to increase output) and pays the Offer price. When supply exceeds demand, NESO accepts Bids (instructing generators to decrease output) and receives the Bid price. The Bid-Offer mechanism operates continuously, with NESO issuing instructions every few seconds during periods of system stress.
“A BSC Party or BSC Party Agent must submit a Physical Notification for each BM Unit for each Settlement Period for which it has registered that BM Unit.”
Elexon, Balancing and Settlement Code, Section P - Section P
This obligation underpins the entire balancing mechanism. Without accurate Physical Notifications from every registered BM Unit, NESO cannot determine the baseline against which imbalance is calculated. Data quality failures here cascade into imbalance pricing errors.
The Balancing Mechanism in practice
The BM is not a market in the traditional sense — it is an administrative mechanism where NESO is the sole buyer and seller. Generators and large demand customers submit Bids and Offers, but they cannot choose their counterparty. NESO selects the most economically efficient combination of Bids and Offers to balance the system, subject to technical constraints (ramp rates, minimum stable generation, transmission congestion).
The data generated by the BM is enormous. Every Bid-Offer submission, every acceptance, every instruction to a generator, and every metered output is recorded and published by Elexon. This data is publicly available and forms the basis for real-time market analysis, academic research, and regulatory oversight. The BM also generates the System Buy Price and System Sell Price that drive imbalance settlement.
What is the purpose of a Final Physical Notification (FPN) in the settlement process?
The Balancing Mechanism closes at gate closure. From that point, three BSC agents take over: SVAA, SAA, and FAA convert the half-hourly metered data into the financial cash flows that settle the market.
10.2 SVAA, SAA, and FAA: the three BSC agents
After the half-hour is over, three BSC agents process the data to determine who owes what. Each agent performs a distinct function, and the output of each feeds into the next.
Supplier Volume Allocation Agent (SVAA)
The SVAA operates at each of the approximately 350 Grid Supply Points (GSPs) across England, Wales, and Scotland. A GSP is the point where the transmission network connects to the distribution network. The SVAA takes all the metered consumption data for each supplier's customers within a GSP and allocates the total consumption to that supplier.
This allocation is crucial because wholesale electricity prices vary by GSP. The GSP Group Correction Factor accounts for distribution losses and unmetered supplies. Under the current profile-based settlement, the SVAA uses load profiles to estimate half-hourly consumption for non-half-hourly settled meters. Under MHHS, actual half-hourly data replaces profiles, dramatically improving allocation accuracy.
Settlement Administration Agent (SAA)
The SAA takes the SVAA's allocations and calculates each supplier's imbalance. For each half-hour at each GSP, the SAA compares the supplier's metered volume (from SVAA) against its contracted volume (from Forward Contract Notifications and accepted Bid-Offer volumes). The difference is the supplier's imbalance volume.
If the supplier consumed more than it contracted (it is “short”), it must buy the shortfall at the System Buy Price (SBP). If it consumed less than it contracted (it is “long”), it sells the surplus at the System Sell Price (SSP). The SBP is always higher than the SSP — this price asymmetry is deliberate, creating a financial incentive for suppliers to forecast their demand accurately and contract accordingly. The spread between SBP and SSP can be substantial: during periods of system stress, SBP can spike to thousands of pounds per MWh while SSP remains near the wholesale average.
Funds Administration Agent (FAA)
The FAA takes the SAA's imbalance calculations and arranges the actual cash flows between BSC Trading Parties. The FAA calculates the net position of each party, issues payment instructions, and settles the cash. Settlement payments flow through a central clearing account, with the FAA ensuring that total credits equal total debits across the market.
The FAA also manages credit cover requirements. Each BSC Trading Party must maintain credit cover (a letter of credit or cash deposit) sufficient to cover its expected settlement exposure. Credit cover protects the market against default: if a supplier goes bust, the credit cover ensures that its settlement debts are paid. The calculation of required credit cover depends directly on settlement data accuracy — better data means more accurate exposure estimates, which means lower credit cover requirements.
The settlement timetable
Settlement does not produce a single final answer. Instead, it runs multiple times as more actual data becomes available:
SF (Settlement Final) — the initial run, at Working Day 5 after the settlement day. Uses whatever actual meter data is available (approximately 95% for smart meters) and estimates the rest.
R1 (First Reconciliation) — approximately 5 months after the settlement day. Incorporates more actual readings and corrects estimates.
R2 (Second Reconciliation) — approximately 10 months after. Uses even more actual data.
R3 (Third Reconciliation) — approximately 14 months after. Nearly all actual data is now available.
RF/DF (Run Final / Dispute Final) — at 28 months, the books are closed. Any remaining disputes must be resolved through the BSC dispute resolution process.
Under MHHS, this timeline compresses dramatically. The RF moves from 28 months to approximately 4 months. This compression is possible because smart meters provide actual half-hourly data within days rather than requiring months of estimation and reconciliation. The financial impact is significant: Elexon estimates that the reduced settlement timeline reduces industry credit cover requirements by approximately 71%, freeing up hundreds of millions of pounds in working capital.
“The System Buy Price shall be calculated as the weighted average price of accepted Offers used to balance the system in a Settlement Period, and the System Sell Price shall be calculated as the weighted average price of accepted Bids.”
Elexon, Balancing and Settlement Code, Section T - Section T
This definition is the core of imbalance settlement. Because Offers (to increase output) are priced higher than Bids (to reduce output) in most periods, SBP is structurally higher than SSP. A supplier that is 'short' buys at SBP; a supplier that is 'long' sells at SSP — creating the asymmetric penalty that incentivises accurate demand forecasting.
Common misconception
“The System Buy Price and System Sell Price are the same, just for different directions.”
SBP and SSP are deliberately asymmetric. SBP (what you pay for being short) is always higher than SSP (what you receive for being long). This spread creates a financial incentive for accurate demand forecasting. During system stress, SBP can spike to thousands of pounds per MWh while SSP stays near wholesale averages. The asymmetry is a design feature, not a flaw — it is the market's way of punishing poor forecasting.
The three BSC agents settle the wholesale market between generators and suppliers. Section 10.3 follows the resulting costs upstream through the wholesale market layers and downstream onto the consumer bill.
10.3 Wholesale markets and the consumer bill
Four layers of wholesale trading
Before electricity reaches the Balancing Mechanism, it is traded through multiple market layers. Understanding these layers explains why wholesale costs represent approximately 45% of the average consumer bill.
- Forward markets: operate months or years ahead. Generators and suppliers trade standardised contracts (baseload and peakload blocks) to hedge their future exposure. By the time a settlement period arrives, 90-95% of expected demand has already been contracted. Prices are published by exchanges (ICE Endex, EEX).
- Day-ahead markets: operate the day before delivery via an auction (N2EX, operated by Nord Pool) that clears at a single marginal price per hour. Day-ahead prices are used in retail tariff calculations and CfD settlements.
- Intraday markets: operate continuously from midnight until gate closure (one hour before the settlement period). Used to adjust positions as demand forecasts change or wind output varies. Volumes have grown with renewable penetration.
- Balancing Mechanism: the final layer, from gate closure until real time. NESO uses Bids and Offers to balance the system, and the resulting costs are socialised through imbalance settlement.
Consumer bill composition
The average GB consumer electricity bill can be broken down into five components. These proportions vary with wholesale prices and regulatory changes, but the approximate split (as of early 2026) is:
Wholesale energy (~45%) — the cost of generating and purchasing the electricity. This includes forward contracts, day-ahead purchases, intraday adjustments, and imbalance costs. The wholesale component is the most volatile, driven by gas prices (which set the marginal price in most settlement periods), renewable output, and demand levels.
Network charges (~27%) — the cost of transmitting and distributing the electricity. This includes Transmission Network Use of System (TNUoS) charges and Distribution Use of System (DUoS) charges. Network charges are regulated through RIIO price controls and are relatively stable year-to-year.
Policy costs (~13%) — the cost of government environmental and social policies. This includes Contracts for Difference (CfD) payments to renewable generators, the Warm Home Discount scheme, and the Energy Company Obligation (ECO). Policy costs have grown significantly as renewable capacity has expanded, though CfD costs are increasingly offset by periods when wholesale prices exceed the CfD strike price (resulting in payments flowing from generators back to consumers).
Operating costs (~10%) — the supplier's costs of running the business. This includes billing systems, customer service, metering (including DCC charges for smart meter infrastructure), regulatory compliance, and profit margin. Ofgem's price cap methodology sets an allowance for these costs based on an efficient benchmark.
VAT (5%) — domestic energy supply is subject to a reduced VAT rate of 5%, applied to the total of all other components.
Supplier failure and SoLR
The 2021 energy crisis exposed the fragility of the supplier market when wholesale prices spiked. Between August 2021 and February 2022, 29 energy suppliers failed, affecting approximately 4.3 million customers. Ofgem used the Supplier of Last Resort (SoLR) mechanism to transfer customers to surviving suppliers, who then recovered the costs (approximately £2.7 billion) through a levy on all consumer bills.
The crisis demonstrated the direct link between wholesale market data, settlement accuracy, and consumer protection. Suppliers that failed had typically hedged poorly (buying too little forward, leaving excessive exposure to spot prices) or had insufficient credit cover to meet their settlement obligations. Better settlement data, faster reconciliation, and more accurate credit cover calculations — all of which MHHS delivers — would have identified some of these risks earlier.
MHHS credit cover improvement
One of the most tangible benefits of MHHS is the reduction in credit cover requirements. Under the current settlement timetable, suppliers must maintain credit cover for up to 28 months of potential settlement adjustments. Under MHHS, the final reconciliation moves to approximately 4 months, reducing the period of exposure by 86%.
Elexon estimates that this reduces total industry credit cover requirements by approximately 71%, freeing up hundreds of millions of pounds in working capital that suppliers can use for other purposes — including hedging, investment, and potentially passing savings on to consumers. This reduction is possible because smart meters provide actual half-hourly data quickly, eliminating the need for the extended estimation and reconciliation process that the current timetable exists to accommodate.
REMIT and market transparency
The Regulation on Energy Market Integrity and Transparency (REMIT) requires that wholesale energy market data is published to support market integrity. Generators must publish generation availability, interconnector flows, and inside information that could affect prices. Ofgem monitors compliance and can impose penalties for market manipulation or insider trading. The data published under REMIT is one of the richest publicly available energy datasets in Europe, providing transparency that supports research, analysis, and informed trading.
By approximately how much does MHHS reduce industry credit cover requirements compared to the current settlement timetable?
Key takeaways
- The settlement chain starts with generators submitting Physical Notifications and Bid-Offer pairs to NESO. The Balancing Mechanism accepts Bids (to reduce output) and Offers (to increase output) to balance supply and demand in real time, generating the SBP and SSP imbalance prices.
- Three BSC agents process settlement data: SVAA allocates metered consumption to ~350 GSPs, SAA calculates each supplier's imbalance (contracted vs actual), and FAA arranges cash flows. SBP/SSP asymmetry deliberately penalises poor demand forecasting to incentivise accuracy.
- The settlement timetable runs multiple times (SF → R1 → R2 → R3 → RF/DF) over 28 months, compressing to ~4 months under MHHS. This compression reduces industry credit cover by an estimated 71%, freeing hundreds of millions in working capital.
- A consumer bill comprises wholesale energy (~45%), network charges (~27%), policy costs (~13%), operating costs (~10%), and VAT (5%). The 2021 supplier crisis (29 failures, 4.3M customers affected, £2.7B SoLR costs) demonstrated that settlement data accuracy directly affects consumer protection.
Standards and sources cited in this module
Elexon, BSC Section T: Settlement Administration
Imbalance calculation, SBP/SSP derivation, reconciliation timetable
Defines the SAA calculation methodology, imbalance pricing, and the settlement run schedule. Referenced throughout Sections 10.1 and 10.2.
Elexon, MHHS Programme — Credit Cover Impact Assessment
Credit cover reduction estimates
Source for the 71% credit cover reduction estimate and the compressed settlement timetable under MHHS. Referenced in Section 10.3.
Ofgem, Supplier of Last Resort — Lessons Learned (2022)
2021 supplier failure analysis and cost recovery
Source for the 29 supplier failures, 4.3M affected customers, and £2.7B SoLR cost figures. Referenced in Section 10.3.
Module 10 of 15 · Energy System Data Applied