REGIONAL CONSTRAINT PRICING AND SETTLEMENT SYSTEMS

1. Introduction

Regional constraint pricing and settlement systems govern how electricity prices and financial obligations are determined when transmission capacity differs between geographical areas. Electricity cannot always flow freely from regions with surplus generation to regions with high demand because transmission networks have thermal, voltage and stability limits. Ofgem explains that such constraints can prevent the economically efficient national dispatch from being physically accommodated.

A regional pricing framework incorporates these physical limitations into market prices, while a conventional national market may calculate one wholesale price and subsequently use redispatch or balancing actions to manage constraints.

2. Nature of Regional Constraint Pricing

Under regional or zonal pricing, the market is divided into geographical zones. Each zone may receive a different electricity price depending upon local supply, demand and transmission capacity.

An export-constrained region with abundant generation may experience lower prices, while an import-constrained region may experience higher prices. A more granular nodal pricing system calculates prices at individual network nodes and can incorporate network constraints and losses more precisely.

The legal significance is substantial because pricing becomes partly dependent upon the physical architecture of the network. Market rules must therefore coordinate dispatch, transmission rights, settlement, congestion management and consumer charges.

3. Settlement Architecture

Settlement determines the financial consequences of physical electricity transactions. A regional system requires rules establishing:

the relevant geographical pricing zone;

the applicable settlement interval;

metering and verification requirements;

treatment of transmission losses;

congestion rents;

imbalance charges;

redispatch payments;

inter-zonal transmission capacity; and

allocation of constraint-management costs.

Errors in settlement can create significant financial transfers between generators, suppliers and consumers. Consequently, settlement methodologies must be transparent, predictable and capable of independent verification.

4. UK Regulatory Framework

Great Britain currently operates a national wholesale market in which transmission constraints are principally managed after market scheduling through the Balancing Mechanism and other redispatch tools. Ofgem's assessment found that transmission constraint costs had increased substantially, with annual thermal constraint costs reaching approximately £1.3 billion in 2022.

Ofgem has therefore examined potential zonal and nodal locational wholesale pricing as alternatives. Its analysis indicates that more granular pricing could reduce some constraint-management costs while producing different wholesale prices between regions.

The present framework also addresses market power during transmission constraints. Generation Licence Standard Condition 20A—the Transmission Constraint Licence Condition (TCLC)—restricts excessive benefits obtained from bids submitted during transmission-constraint periods.

5. Case Law: R (SSE Generation Ltd) v Gas and Electricity Markets Authority [2022] EWCA Civ 1472

Facts: SSE and other electricity-sector participants challenged aspects of GEMA's methodology concerning electricity transmission charges. The dispute concerned how congestion-management costs were treated when determining transmission charges.

Legal Issue: Whether GEMA had lawfully interpreted and applied the relevant European and domestic legal framework when modifying the methodology for transmission charging.

Judgment: The Court of Appeal considered the statutory and regulatory requirements governing transmission charges and addressed the limits of GEMA's powers to implement an interim methodology.

Legal Principle/Ratio: A specialist energy regulator must exercise its powers consistently with the governing legal framework; technical expertise does not permit departure from mandatory legal requirements.

Significance: The case is directly relevant to regional constraint pricing because charging and congestion methodologies are legally structured regulatory instruments, rather than purely technical market-design choices.

6. Case Law: R (British Gas Trading Ltd) v GEMA [2019] EWHC 1926 (Admin)

Facts: British Gas challenged GEMA's methodology for establishing the domestic energy price cap, including the treatment of wholesale energy costs.

Legal Issue: Whether GEMA had lawfully exercised its statutory pricing powers.

Judgment: The Administrative Court examined the statutory requirements governing GEMA's price-setting methodology and the regulator's consideration of relevant cost information. The case illustrates judicial scrutiny of complex energy-pricing decisions.

Legal Principle/Ratio: Regulatory pricing decisions must remain within statutory powers and must properly address legally relevant considerations.

Significance: The principle extends to regional settlement systems: sophisticated mathematical or market models cannot replace lawful statutory authority, reasoned decision-making and transparent methodology.

7. Market Power and Consumer Protection

Regional constraints can create temporary local market power because only a limited number of generators may be capable of relieving a particular constraint. Ofgem expressly identifies this risk and uses the TCLC to prevent generators from obtaining excessive benefits from constrained dispatch.

This is particularly important where generators can influence constraint bids, redispatch payments or settlement outcomes. In 2023, Ofgem found that SSE had breached the TCLC concerning payments associated with reducing generation at Foyers and required £9.78 million to be paid into the Energy Redress Fund.

8. Conclusion

Regional constraint pricing transforms electricity regulation by connecting geographical network scarcity with market prices and financial settlement. Its legal framework must balance efficient dispatch against market power, consumer protection, investment incentives and predictable settlement.

For a decarbonised electricity system, the issue becomes increasingly important because renewable generation may be concentrated in particular geographical areas while demand and network capacity are unevenly distributed. A legally robust regional pricing regime therefore requires clear pricing rules, transparent settlement methodologies, congestion safeguards, accurate metering, regulatory oversight and judicially reviewable decision-making.