1. Introduction

Interconnection congestion management refers to the legal, regulatory, and technical mechanisms used to manage situations where requests to connect electricity generation, storage, consumers, or cross-border transmission transactions exceed the available capacity of the transmission or distribution network.

Congestion can arise in two related contexts:

Physical network congestion — existing transmission facilities cannot safely carry all desired power flows.

Interconnection-queue congestion — a large number of projects seek grid connection, creating delays in studies, network reinforcement, and allocation of available capacity.

Modern electricity systems make this issue particularly important because renewable-energy projects, battery storage, electric vehicles, data centres, and distributed generation can create large volumes of connection requests.

A sound legal framework therefore has to reconcile grid reliability, non-discrimination, economic efficiency, transparency, timely connection, cost allocation, and consumer interests.

2. Meaning of Interconnection Congestion

An electricity network has a finite thermal, voltage, stability and transfer capability. Suppose several generators seek connection to the same transmission corridor:

Generator A requests 500 MW;

Generator B requests 400 MW;

Generator C requests 300 MW;

but the available network capability is only 600 MW.

The regulator cannot simply allow every applicant to inject its requested capacity. Doing so could violate:

thermal limits;

voltage limits;

frequency stability;

transient stability;

N-1 security standards;

protection requirements; and

system reliability obligations.

Congestion management therefore determines which transactions or projects can use scarce network capacity, when they can use it, and who must bear the cost of relieving the constraint.

3. Principal Elements of a Legal Framework

A. Capacity assessment

The first requirement is a legally recognised process for determining available transmission capacity.

This normally involves:

power-flow studies;

contingency analysis;

stability analysis;

short-circuit studies;

available transfer capability;

network-reinforcement requirements; and

increasingly, probabilistic and scenario-based modelling.

The methodology must be sufficiently transparent to permit regulatory and, where appropriate, judicial review.

B. Interconnection queues

Where connection requests exceed available capacity, applicants are placed in an interconnection queue.

Traditional systems often used a first-come, first-served model. This can create problems because speculative projects may occupy queue positions for years without reaching construction.

Modern frameworks therefore increasingly use:

cluster studies;

milestone requirements;

financial security;

withdrawal penalties;

readiness criteria;

periodic queue management; and

deadlines for completing studies.

The United States provides an important example. FERC's Order No. 2003 standardised large-generator interconnection procedures and required transmission providers to use structured procedures for processing requests. (Federal Energy Regulatory Commission)

FERC's original rule specifically recognised clustering as a mechanism for assessing multiple requests together and coordinating transmission expansion with the anticipated use of the network. (Federal Energy Regulatory Commission)

4. First-Come, First-Served versus Cluster-Based Management

First-Come, First-Served

Under the traditional model:

earlier application → earlier study → earlier connection opportunity.

Its advantage is procedural simplicity.

However, it can produce a significant problem: a project that entered the queue first may require expensive network reinforcement even though a later group of projects could collectively use the network more efficiently.

Cluster-based approach

Under a cluster approach, projects located in electrically related areas are studied together.

This allows the system operator to determine:

aggregate network impact;

common transmission upgrades;

interaction between projects;

total reinforcement requirements; and

whether particular projects remain commercially viable.

FERC's Order No. 2003 expressly recognised clustering as a means of evaluating pending interconnection requests systematically against the capability of the transmission system. (Federal Energy Regulatory Commission)

5. Congestion Allocation Mechanisms

A legal framework must also determine who receives scarce capacity.

Common mechanisms include:

5.1 Administrative allocation

The regulator or system operator establishes priority rules.

Examples include priority based on:

queue position;

project readiness;

public-interest status;

renewable-energy status;

contractual rights; or

previously acquired transmission rights.

5.2 Market-based allocation

Capacity can be allocated through:

auctions;

congestion pricing;

transmission rights;

financial transmission rights;

implicit allocation through energy markets.

5.3 Hybrid systems

Many modern systems combine administrative connection rules with market-based congestion management.

6. Congestion Pricing

Where transmission capacity is scarce, electricity prices can differ between locations.

If electricity is abundant in Zone A but transmission capacity toward Zone B is constrained, the market may produce:

Zone A price < Zone B price

The difference represents, among other things, the economic value associated with the transmission constraint.

Congestion pricing can therefore provide signals concerning:

where new generation should locate;

where storage is valuable;

where transmission investment is required; and

when demand response can relieve constraints.

However, pricing alone cannot replace physical reliability standards. A transmission system cannot be operated beyond its safe engineering limits merely because market participants are willing to pay.

7. Cross-Border Interconnection Congestion

Congestion becomes legally more complex when electricity crosses national borders.

The European Union provides one of the most developed examples. EU electricity legislation provides for cross-zonal capacity allocation and congestion management through instruments including Regulation (EU) 2019/943 and Commission Regulation (EU) 2015/1222.

Modern European frameworks increasingly use flow-based capacity calculation, which recognises that electricity does not necessarily follow the contractual path selected by traders.

This creates difficult legal questions concerning:

bidding zones;

cross-border capacity;

internal network elements;

power-transfer distribution factors (PTDFs);

redispatching;

countertrading;

transmission-system operators' responsibilities; and

ACER's regulatory authority.

8. BNetzA and Germany v ACER — 2025

A particularly important recent case is BNetzA and Germany v ACER, Joined Cases T-600/23 and T-612/23, decided by the EU General Court on 1 October 2025.

The litigation concerned common methodologies for calculating day-ahead and intraday cross-zonal transmission capacity in the EU's Core capacity-calculation region.

The dispute involved the classification of internal critical network elements and the use of flow-based methodologies, including PTDF calculations.

The General Court held that ACER could not classify critical network elements using requirements that went beyond the legal criteria established by the applicable EU legislation. It partially annulled the relevant ACER Board of Appeal decision. (InfoCuria)

Legal significance

The case demonstrates an important principle:

Congestion-management methodologies must remain within the legal authority granted by the governing legislation.

Technical complexity does not give regulators unlimited discretion.

The case also illustrates judicial scrutiny of highly technical energy regulation. Courts may examine whether the regulator has:

correctly interpreted the legislation;

stayed within its statutory authority;

applied the prescribed methodology; and

adequately respected the legal criteria governing capacity calculation.

9. Interconnection Queue Reform in the United States

The United States has experienced substantial interconnection congestion.

In Advanced Energy United v. FERC, No. 23-1282 (D.C. Cir. 2026), the D.C. Circuit considered FERC's Order No. 2023 reforms to the generator interconnection process.

The court described the problem as involving approximately 2,600 GW of proposed generation and storage capacity in interconnection queues at the end of 2023, with projects experiencing lengthy delays. FERC responded by replacing the traditional serial process with a cluster-study framework, together with financial and procedural requirements intended to make the queue more manageable. (Justia Law)

Importance

The case illustrates a transition from:

"queue position determines the study sequence"

toward:

"projects are studied collectively and must demonstrate greater readiness."

This is especially relevant to renewable-energy and battery-storage development.

10. FERC Order No. 2003

FERC's Order No. 2003 is one of the foundational US regulatory instruments concerning generator interconnection.

It established standardised:

Large Generator Interconnection Procedures;

Large Generator Interconnection Agreement;

technical study processes;

interconnection responsibilities; and

cost-allocation mechanisms.

FERC's subsequent orders modified and refined the framework. FERC identifies Order Nos. 2003, 2003-B and 2003-C among its major regulatory actions concerning generator interconnection. (Federal Energy Regulatory Commission)

The framework is legally significant because it attempts to reduce discriminatory treatment by requiring transmission providers to operate under standardised procedures.

11. National Association of Regulatory Utility Commissioners v. FERC

In National Association of Regulatory Utility Commissioners v. FERC, the D.C. Circuit reviewed FERC's Order No. 2003 rulemaking.

The litigation concerned FERC's authority and standardisation of open-access transmission tariffs, generator interconnection procedures and agreements. (Federal Energy Regulatory Commission)

Principle

The case demonstrates the broader legal tension between:

federal regulatory authority;

transmission-provider obligations;

state regulatory jurisdiction; and

standardised interconnection rules.

It is therefore relevant when considering the constitutional and administrative foundations of congestion-management frameworks in vertically and jurisdictionally divided electricity systems.

12. India: Interconnection and General Network Access

India has developed a regulatory framework around connectivity and General Network Access (GNA) to the inter-State Transmission System.

The Central Electricity Regulatory Commission (CERC) maintains the regulatory framework concerning connectivity and GNA and has published the applicable detailed procedures and subsequent amendments. (CERC)

This framework is particularly significant because India's electricity system increasingly involves:

renewable-energy zones;

interstate power transfers;

large solar and wind projects;

transmission corridors;

open access;

storage;

changing generation locations; and

increasing network congestion.

CERC's current regulatory materials also show continuing amendments and consultation concerning connectivity and GNA during 2026. (CERC)

13. Cost Allocation for Congestion Relief

One of the most difficult legal questions is:

Who pays for the network reinforcement required to relieve congestion?

Possible models include:

Generator pays

The connecting generator bears the cost attributable to its connection.

Beneficiary pays

Those benefiting from the reinforcement contribute according to the benefits received.

Socialised transmission cost

Costs are distributed among a wider group of network users.

Hybrid allocation

A combination of:

connection-specific costs;

shared network costs; and

system-wide transmission charges.

The choice has major consequences for investment incentives.

A system that imposes all reinforcement costs on individual generators may discourage projects. Conversely, complete socialisation may encourage inefficient projects to seek connection because their network costs are transferred to other users.

14. Non-Discrimination and Open Access

Congestion management must comply with the principle of non-discriminatory access.

A transmission operator should not favour:

its affiliated generator;

a particular technology without lawful justification;

an incumbent participant;

a preferred commercial counterparty; or

a particular geographic region without a legitimate regulatory basis.

Open-access rules are therefore closely connected to congestion-management law.

Legal review may arise where an applicant alleges:

preferential treatment;

arbitrary queue movement;

discriminatory study treatment;

unjustified curtailment;

inconsistent cost allocation; or

inadequate disclosure of available capacity.

15. Curtailment as a Congestion-Management Tool

Where network constraints remain after connection, the system operator may need to curtail generation.

Curtailment can be:

economic;

reliability-driven;

emergency-based;

redispatch-based; or

contractually agreed.

The legal framework must establish:

when curtailment is permitted;

who may order it;

the priority order;

whether compensation is payable;

how compensation is calculated; and

how disputes are resolved.

This becomes particularly important for renewable generators because excessive or unpredictable curtailment can undermine project financing.

16. Redispatch and Countertrading

In advanced electricity markets, congestion can be managed without physically refusing every transaction.

Redispatch

The system operator:

reduces output from one generator; and

increases output from another generator.

Countertrading

The operator undertakes transactions that offset the physical effects of congestion.

These mechanisms can preserve market transactions while maintaining physical security.

However, they create legal questions concerning:

compensation;

market neutrality;

cost recovery;

abuse prevention;

transparency; and

allocation of redispatch costs.

17. Regulatory Governance

An effective framework normally divides responsibilities among:

Regulator → System Operator → Transmission Owner → Market Operator → Generator/Consumer

The regulator establishes:

access rules;

congestion methodology;

cost allocation;

performance standards;

reporting obligations.

The system operator performs:

network studies;

capacity calculations;

congestion identification;

dispatch/redispatch;

reliability management.

The transmission owner performs:

construction;

reinforcement;

maintenance;

connection works.

This institutional separation reduces opportunities for discriminatory treatment.

18. Transparency and Procedural Fairness

Congestion management is not merely an engineering question.

Applicants require sufficient information concerning:

queue position;

available capacity;

study assumptions;

network constraints;

required reinforcements;

estimated connection dates;

cost estimates;

reasons for delay;

curtailment expectations.

A legally robust framework should provide:

application → technical study → decision → reasons → review/appeal

This is particularly important because interconnection decisions can determine whether a billion-dollar infrastructure project is commercially viable.

19. ACER v Aquind

Another important EU case is ACER v Aquind, Case C-46/21 P, decided by the Court of Justice on 9 March 2023.

The case concerned an application for an exemption relating to an electricity interconnector between Great Britain and France and examined the role of ACER and its Board of Appeal in reviewing regulatory decisions. (InfoCuria)

Although not purely a congestion case, it is relevant to interconnection governance because cross-border interconnectors depend upon regulatory decisions concerning access, exemptions and market arrangements.

The case demonstrates the importance of effective administrative review in highly technical energy regulation.

20. Legal Principles Emerging from the Case Law

Several principles can be identified.

1. Regulatory authority must have a legal foundation

In BNetzA v ACER, the General Court emphasised that technical congestion methodologies must remain within the limits established by EU legislation. (Court of Justice of the European Union)

2. Standardisation can promote non-discrimination

FERC's interconnection framework demonstrates the regulatory value of standardised procedures rather than individually negotiated access arrangements. (Federal Energy Regulatory Commission)

3. Queue management can be redesigned

The US experience demonstrates that a regulator can move from serial processing toward cluster-based procedures where the existing model produces systemic delays. (Justia Law)

4. Technical decisions remain legally reviewable

Courts and regulatory appeal bodies can review highly technical capacity-calculation decisions for legality, jurisdiction and compliance with governing rules.

5. Congestion management must balance competing interests

The legal framework must reconcile:

generator access;

consumer protection;

reliability;

competition;

transmission investment;

renewable integration; and

affordability.

21. Major Challenges

A. Renewable-energy concentration

Large renewable projects are often located far from demand centres, creating transmission bottlenecks.

B. Battery storage

Storage can both increase and reduce congestion depending on charging and discharging behaviour.

C. Data centres and electrification

Rapidly growing electricity demand can create new connection queues.

D. Speculative queue entries

Projects that are not construction-ready can occupy valuable network capacity.

E. Transmission investment delays

Even where congestion is clearly identified, obtaining planning approvals and financing for new transmission can take years.

F. Cross-border complexity

Different national regulatory regimes can complicate coordinated congestion management.

22. Recommended Legal Architecture

A comprehensive interconnection congestion framework should contain the following components:

23. Conclusion

Interconnection congestion management frameworks are a central component of modern electricity law. Their purpose is not simply to determine whether a generator can connect to the grid; they determine how scarce network capacity is allocated among competing users while preserving system reliability and market fairness.

The regulatory evolution in the United States—from traditional interconnection queues toward cluster-based approaches—and the European Union's sophisticated flow-based cross-zonal capacity regime demonstrate two important trends: greater coordination of network users and increasing legal scrutiny of technical methodologies. (Justia Law)

For India, the development of CERC's connectivity and GNA framework is particularly important because growing renewable generation and interstate electricity flows make transmission-capacity allocation increasingly significant. CERC's continuing amendments and procedures show that the regulatory architecture remains an evolving field. (CERC)

Ultimately, a legally robust congestion framework should combine transparent capacity calculation, fair queue management, non-discriminatory access, technically justified curtailment, rational cost allocation, coordinated transmission planning, and effective regulatory review. These principles allow electricity networks to accommodate increasing generation and demand without sacrificing reliability or procedural fairness.