1. Introduction

Curtailment in electricity markets occurs when a generator that is technically capable of producing electricity is instructed to reduce or stop generation, or when the grid operator is unable to evacuate the power that the generator could otherwise have supplied.

Curtailment is particularly important for solar and wind projects because their output depends on natural resources and because renewable generation is generally given preferential or must-run treatment under India's electricity regulatory framework.

A curtailment dispute can therefore involve questions of:

whether the curtailment was legally justified;

whether the grid operator followed dispatch rules;

whether the Power Purchase Agreement (PPA) permits curtailment;

whether the generator is entitled to deemed-generation compensation;

who bears transmission-congestion risk;

whether the instruction was issued for genuine grid security;

whether the generator received proper reasons and records;

which regulatory commission has jurisdiction; and

whether the dispute should be resolved through regulatory adjudication, arbitration, judicial review, or another mechanism.

Indian jurisprudence has developed a particularly important principle: renewable-energy curtailment cannot ordinarily be used as a commercial or economic dispatch mechanism when the applicable legal framework gives renewable generation must-run status. A curtailment based on genuine grid-security requirements is treated differently. (Indian Kanoon)

2. Meaning of a Curtailment Claim

A curtailment claim normally arises when a renewable generator contends that:

the grid or purchasing authority prevented it from generating/supplying electricity in circumstances where it was legally entitled to generate and receive payment.

For example:

A 100 MW solar project is available to generate 100 MW, but the SLDC instructs it to generate only 50 MW.

The generator may claim compensation for the lost 50 MW if the instruction was unlawful and the applicable PPA, regulations or judicial framework provide an entitlement to compensation.

The dispute can consequently involve two separate questions:

Question 1 — Was the curtailment lawful?

Question 2 — If it was unlawful, what compensation is payable?

These questions should be kept analytically separate.

3. Legal Sources Governing Curtailment

Curtailment disputes may arise from several overlapping legal instruments.

A. Electricity Act, 2003

The Electricity Act establishes the institutional framework for:

grid management;

load dispatch;

electricity regulation;

tariff;

transmission;

generation; and

adjudication of electricity disputes.

Sections 31 and 32 are particularly relevant to State Load Despatch Centres, while Section 79 is important for CERC jurisdiction and Section 86 for State Commissions.

B. Grid Codes

The applicable national and state grid codes establish operational rules concerning:

scheduling;

dispatch;

grid security;

frequency;

voltage;

transmission constraints;

system emergencies; and

renewable-energy priority.

C. PPA

The PPA may specify:

must-run treatment;

deemed generation;

compensation;

force majeure;

transmission availability;

change in law;

payment obligations; and

dispute resolution.

D. Electricity Rules and Regulations

India's Electricity (Promotion of Generation of Electricity from Must-Run Power Plant) Rules, 2021 expressly recognise certain renewable generating stations as must-run facilities. The judicial record in Tamil Nadu Spinning Mills Association notes that Rule 3 treats wind, solar, wind-solar hybrid and specified hydro projects as must-run where the prescribed conditions are met. (Indian Kanoon)

4. The Must-Run Principle

The most important concept in renewable curtailment litigation is must-run status.

The principle reflects the distinctive characteristics of renewable generation.

Solar and wind generators generally have:

negligible or zero fuel cost;

variable output;

no ability to store electricity without additional storage equipment; and

limited control over when their primary energy resource is available.

Consequently, curtailing renewable generation for purely commercial reasons can undermine the economics of the project.

In National Solar Energy Federation of India v. Tamil Nadu Electricity Regulatory Commission, APTEL dealt extensively with wrongful curtailment of solar generation. The Tribunal considered renewable generation's must-run status and the circumstances in which backing down could be justified. (Indian Kanoon)

5. National Solar Energy Federation of India v. TNERC

Case

National Solar Energy Federation of India v. Tamil Nadu Electricity Regulatory Commission, Appeal No. 197 of 2019, decided by APTEL on 2 August 2021.

This is one of the most important Indian authorities on renewable-energy curtailment.

The dispute concerned widespread curtailment/backing down of solar generation in Tamil Nadu.

Tribunal's approach

The Tribunal examined whether renewable generation could be backed down merely because of economic or commercial considerations.

It identified circumstances in which curtailment could be justified by grid-security considerations, including matters such as:

frequency;

voltage;

transmission constraints;

network loading; and

availability of margins from conventional generation.

The case is significant because it distinguishes legitimate grid-security curtailment from arbitrary or commercially motivated curtailment. (Indian Kanoon)

6. Compensation for Wrongful Curtailment

One of the most important questions is whether a renewable generator should receive compensation for energy that it could have generated but was prevented from supplying.

The APTEL jurisprudence has recognised that wrongful renewable curtailment can give rise to compensation.

In the National Solar Energy Federation litigation, the compensation issue was linked to the tariff under the relevant PPA and the financial loss suffered because renewable generation was wrongfully backed down. (Indian Kanoon)

However, an important qualification exists:

Compensation is not automatically available merely because generation was curtailed.

The generator normally needs to establish:

that it had the capacity and availability to generate;

that curtailment actually occurred;

who issued the instruction;

why the instruction was issued;

whether the reason was legally permissible;

whether the PPA/regulations provide compensation;

the quantity of energy affected; and

the appropriate compensation methodology.

7. Tamil Nadu Spinning Mills Association Case

Another significant decision is Tamil Nadu Spinning Mills Association v. Tamil Nadu Generation and Distribution Corporation Ltd.

The judicial record describes the APTEL framework under which renewable curtailment for reasons other than legitimate grid security was to be compensated at the PPA tariff, with the compensation methodology connected to the POSOCO report. (Indian Kanoon)

The framework also required SLDC reporting concerning the reasons for backing-down instructions.

This demonstrates an important procedural principle:

Curtailment accountability requires records.

An SLDC should be able to demonstrate:

when the instruction was issued;

the quantum curtailed;

the technical reason;

grid conditions;

available transmission capacity;

frequency/voltage conditions; and

why renewable generation had to be backed down.

A bare assertion that "grid security required curtailment" may therefore be insufficient where the governing framework requires evidence and reporting.

8. Andhra Pradesh SLDC v. Axis Wind Farms

The Andhra Pradesh litigation concerning APSLDC and Axis Wind Farms is another important authority.

The Andhra Pradesh High Court considered whether renewable generators could be subjected to curtailment and held that merit-order dispatch does not apply to renewable generation in the same manner as conventional generation where renewable projects enjoy must-run status. (eCourtsIndia)

The court upheld directions restricting coercive curtailment except in accordance with the applicable legal requirements.

Importance

This case demonstrates that:

A grid operator cannot simply treat renewable electricity as another dispatchable resource and choose to reduce it because another source is commercially preferable.

The operator must comply with the applicable statutory and regulatory framework.

9. Transmission Congestion and Curtailment

Transmission constraints create a particularly difficult category of disputes.

Suppose:

a solar project is operational;

the project has a valid PPA;

electricity is available;

but the transmission system cannot evacuate the full output.

The legal question becomes:

Who bears the risk of inadequate transmission capacity?

Potential answers depend on:

the PPA;

transmission agreement;

connectivity agreement;

grid code;

regulatory orders;

cause of congestion; and

applicable compensation provisions.

Recent CERC proceedings demonstrate that curtailment claims based on inadequate transmission evacuation remain an active area of regulatory litigation. For example, CERC records include a 2025 petition seeking compensation and interest for generation losses allegedly caused by backing-down instructions resulting from inadequate transmission infrastructure in Rajasthan. (CERC)

This shows that transmission-related curtailment is increasingly being litigated as a distinct compensation issue rather than simply being treated as ordinary dispatch.

10. Regulatory Dispute Resolution

The first major route is generally through the Electricity Regulatory Commission.

CERC

CERC may have jurisdiction where the dispute falls within the matters assigned to it under Section 79 of the Electricity Act, including certain disputes involving generating companies having an inter-State or composite scheme.

SERC

A State Electricity Regulatory Commission can become relevant where the dispute concerns:

intra-State generation;

State transmission;

distribution;

SLDC functions;

State-level PPAs; or

matters falling within Section 86.

The correct forum therefore depends heavily on the statutory jurisdiction and the structure of the project and PPA.

11. Section 79(1)(f) and Dispute Adjudication

Section 79(1)(f) gives CERC adjudicatory authority over certain disputes involving generating companies or licensees connected with the matters within CERC's jurisdiction.

This provision is frequently invoked in PPA disputes.

Recent CERC proceedings show petitions under Section 79(1)(f) involving contractual and compensation disputes arising from PPAs. (CERC)

But the mere fact that a dispute concerns a PPA does not automatically mean CERC has jurisdiction.

The nature of:

the generator;

the PPA;

the tariff;

the generating scheme;

inter-State supply; and

statutory jurisdiction

must be examined.

12. Arbitration

Many PPAs contain an arbitration clause.

A typical contractual sequence may be:

Operational dispute → notice → negotiation → regulatory determination where required → arbitration

But arbitration cannot always override statutory regulatory jurisdiction.

The interaction between the Electricity Act and arbitration law has been repeatedly litigated.

A recent Delhi High Court decision concerning renewable-energy PPA disputes illustrates the importance of determining whether the dispute falls within the regulatory commission's statutory jurisdiction or is instead a contractual dispute suitable for another forum. (Indian Kanoon)

Therefore, before commencing arbitration, parties should examine:

the arbitration clause;

the Electricity Act;

the relevant commission's jurisdiction;

whether tariff determination is involved;

whether the dispute concerns implementation of a regulatory order; and

whether the statutory scheme displaces ordinary arbitration.

13. Judicial Review

Where the disputed curtailment instruction is issued by a statutory grid operator, constitutional judicial review may also become relevant.

A generator may challenge an action where it alleges:

statutory violation;

breach of grid-code requirements;

arbitrariness;

failure to provide reasons;

violation of natural justice;

improper exercise of statutory power; or

departure from binding regulatory orders.

The writ jurisdiction of High Courts can therefore be relevant, particularly where the dispute concerns the legality of governmental or statutory action rather than merely the interpretation of a commercial contract.

14. Evidentiary Requirements

A strong curtailment claim requires detailed evidence.

Generator should preserve:

1. SCADA records

Showing actual available generation.

2. Scheduling data

Showing scheduled and actual generation.

3. SLDC instructions

Written or recorded backing-down instructions.

4. PPA

Especially must-run and compensation provisions.

5. Grid-code provisions

Showing the circumstances in which curtailment is permitted.

6. Metering data

Establishing the quantity of electricity actually generated or capable of being generated.

7. Transmission information

Showing whether congestion actually existed.

8. Communication records

Emails, notices and operational messages.

9. Revenue calculations

Demonstrating the claimed economic loss.

This evidentiary architecture is essential because curtailment litigation often turns on technical causation, not merely legal interpretation.

15. Deemed Generation

Deemed generation is a contractual or regulatory mechanism under which the generator is financially compensated for electricity it could have generated but was prevented from supplying for reasons attributable to the buyer, grid operator, transmission provider, or another responsible party.

The formula may generally resemble:

Deemed Energy × Applicable PPA Tariff = Compensation

But the actual formula can vary considerably.

An important CERC decision concerning Wardha Solar noted that, in the absence of a specific PPA provision for deemed-generation charges, such compensation cannot simply be assumed, even though renewable energy enjoys must-run status. (CaseMine)

This is an important limitation.

Must-run status ≠ automatic unlimited damages.

The claimant must identify the legal source of the compensation entitlement.

16. Distinguishing Lawful and Unlawful Curtailment

A useful framework is:

The decisive issue is therefore not merely whether electricity was curtailed, but why, under whose authority, according to which legal instrument, and with what consequences.

17. Role of Grid Operators

SLDCs and system operators occupy a special position because they must simultaneously protect:

grid security;

system stability;

consumer supply;

transmission integrity;

frequency;

voltage; and

renewable integration.

Consequently, renewable must-run status is not absolute in the sense of overriding physical grid-security requirements.

The legal balance is:

Renewable priority + grid security.

Where genuine grid security requires curtailment, the operator must be able to demonstrate that the restriction was technically necessary and consistent with the governing legal framework.

18. Procedural Fairness

Curtailment disputes increasingly involve procedural questions.

A generator may ask:

Was notice given?

Was the reason communicated?

Was the decision recorded?

Were alternative generators considered?

Was renewable generation curtailed proportionately?

Was curtailment rotational where required?

Was the instruction reviewed?

Were monthly reports submitted?

Was the decision consistent with previous regulatory directions?

Procedural deficiencies can strengthen a challenge because they make it difficult to establish whether the curtailment was genuinely required for system security.

The Tamil Nadu framework described in the judicial record specifically contemplated monthly SLDC reporting and publication of detailed reasons for backing-down instructions. (Indian Kanoon)

19. Recent Development: Curtailment as a Continuing Regulatory Issue

Curtailment is not merely a historical dispute concerning early solar projects.

CERC's current case records show continuing litigation involving:

curtailment;

open-access restrictions;

transmission constraints;

generation losses; and

compensation claims.

For example, CERC records include a 2026 petition challenging regulation of open access and consequent curtailment of power from a 300 MW generation project. (CERC)

This illustrates how curtailment law is expanding beyond conventional PPA disputes into questions concerning open access, network allocation and transmission governance.

20. International Perspective

Internationally, curtailment disputes are frequently handled through:

regulatory proceedings;

contractual dispute-resolution mechanisms;

administrative courts;

arbitration; and

investment arbitration.

The fundamental legal issue is often similar:

Has the state or network operator exercised its regulatory powers consistently with the generator's contractual and statutory rights?

However, international cases must be assessed carefully because the applicable legal framework may involve:

EU electricity law;

national energy law;

investment treaties;

PPAs;

grid connection agreements; and

arbitration conventions.

Accordingly, foreign decisions should generally be used as comparative jurisprudence, rather than automatically applied to an Indian dispute.

21. Model Legal Framework for Resolving a Curtailment Claim

A comprehensive dispute-resolution mechanism can be structured into six stages.

Stage 1 — Operational verification

Determine:

date;

time;

MW curtailed;

duration;

available generation;

scheduled generation;

actual generation.

Stage 2 — Reason verification

Determine whether the curtailment resulted from:

frequency;

voltage;

transmission congestion;

system emergency;

network security;

commercial dispatch; or

another reason.

Stage 3 — Legal classification

Compare the instruction with:

Electricity Act;

Grid Code;

Must-Run Rules;

SERC/CERC regulations;

PPA;

transmission agreement.

Stage 4 — Attribution

Identify the responsible entity:

SLDC;

STU;

CTU;

DISCOM;

PPA counterparty;

transmission licensee; or

another entity.

Stage 5 — Quantification

Calculate:

Available generation − permitted/actual generation = curtailed energy

Then determine:

Curtailed energy × applicable compensation rate = claimed amount

subject to the specific contractual/regulatory methodology.

Stage 6 — Forum

Select the legally appropriate mechanism:

SERC;

CERC;

APTEL;

High Court;

arbitration;

contractual dispute mechanism; or

another competent forum.

22. Major Case-Law Principles

The principal propositions emerging from Indian curtailment jurisprudence can be summarised as follows:

1. Renewable generation receives must-run protection

The legal framework strongly protects renewable generation from arbitrary backing down. (Indian Kanoon)

2. Grid security remains a legitimate exception

Curtailment can be justified where necessary to protect the security and stability of the electricity system. (Indian Kanoon)

3. Commercial preference is not equivalent to grid security

An operator cannot ordinarily invoke "grid security" as a general justification for economically motivated curtailment without supporting technical evidence.

4. Compensation depends upon legal entitlement

Must-run status does not necessarily create an unlimited right to deemed-generation compensation; the PPA and applicable regulatory framework remain important. (CaseMine)

5. Evidence matters

SLDC records, scheduling data, SCADA information and technical explanations are central to determining whether curtailment was lawful.

6. Jurisdiction must be determined carefully

A PPA dispute may fall before CERC, SERC, an arbitral tribunal or a court depending on the statutory framework and contractual structure. (Indian Kanoon)

23. Conclusion

Legal dispute resolution for curtailment claims sits at the intersection of electricity regulation, contract law, administrative law and renewable-energy policy.

Indian jurisprudence has developed a relatively clear conceptual distinction between lawful curtailment required for genuine grid security and unlawful or arbitrary curtailment that undermines renewable generators' statutory and contractual protections.

The decisions in National Solar Energy Federation of India v. TNERC, the Tamil Nadu Spinning Mills Association litigation, and APSLDC v. Axis Wind Farms establish important principles concerning renewable must-run status, permissible grid-security curtailment and compensation. (Indian Kanoon)

At the same time, Wardha Solar demonstrates an important limitation: the existence of must-run status does not by itself establish an unrestricted claim for deemed-generation compensation where the governing PPA contains no corresponding compensation mechanism. (CaseMine)

Thus, a successful curtailment claim normally requires a carefully documented chain:

Legal entitlement → valid generation availability → curtailment instruction → absence of lawful justification → attributable loss → contractual/statutory compensation → competent dispute-resolution forum.

This framework is becoming increasingly important as India's electricity system accommodates larger quantities of variable renewable energy and encounters greater transmission, congestion, storage and system-balancing challenges. (CERC)