1. Meaning and concept

Time-of-Day (ToD) tariffs are electricity pricing arrangements under which the price of electricity varies according to the time at which it is consumed. Electricity may cost more during periods of high demand and less during periods when demand is lower or renewable energy is abundant.

In India, this concept is closely connected with electricity tariff regulation, smart metering, demand-side management, renewable energy integration, and the powers of electricity regulatory commissions.

The basic principle is that the price of electricity should reflect, as far as practicable, the cost and system conditions associated with supplying electricity at different times.

For example, electricity demand may rise sharply during evening hours when households use lights, fans, air conditioners and cooking appliances. If the power system is already heavily loaded, supplying additional electricity may require more expensive generation or create network constraints. A higher peak-period tariff can encourage consumers to shift flexible consumption to other hours.

2. How Time-of-Day tariffs work

Peak hours — higher tariff

High demand

These are periods when electricity demand or system costs are high. Higher prices encourage consumers to reduce or postpone flexible loads.

Solar or off-peak hours — lower tariff

Potentially lower cost

Where solar generation is abundant and the tariff structure supports it, consumers may be encouraged to operate pumps, charge batteries or run suitable industrial processes during these hours.

Smart metering and billing

Smart meters or other approved interval-metering arrangements record consumption in different time blocks so the applicable tariff can be calculated.

The exact peak, off-peak and solar-hour periods depend on the applicable tariff order, consumer category and electricity regulations. They are not necessarily identical across states or distribution licensees.

3. Legal framework governing ToD tariffs in India

The principal legal framework consists of the Electricity Act, 2003, the Electricity (Rights of Consumers) Rules, 2020, their amendments, the Tariff Policy, and tariff orders issued by State Electricity Regulatory Commissions (SERCs).

A. Electricity Act, 2003

Section 61 is particularly important because ToD tariffs must be designed within the statutory framework governing electricity pricing. A time-sensitive tariff cannot be treated as an arbitrary surcharge disconnected from the applicable regulations and tariff order.

B. Electricity (Rights of Consumers) Rules, 2020

On 23 June 2023, the Ministry of Power announced amendments introducing a more explicit ToD framework. The central policy provided for reduced tariffs during designated solar hours and increased tariffs during designated peak hours.

Press Information Bureau

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The announced framework included:

Solar-hour electricity rates 10–20% below the normal tariff.

Peak-period rates 10–20% above the normal tariff.

Implementation linked to smart-meter installation.

Staggered applicability for commercial, industrial and other non-agricultural consumers.

The 2023 announcement specified implementation deadlines of 1 April 2024 for covered commercial and industrial consumers with maximum demand of 10 kW or more, and 1 April 2025 for other non-agricultural consumers. These dates should not be confused with proof that every individual connection has actually been placed on ToD billing.

Important current-law qualification: In 2026, the Ministry also published a draft proposing revised implementation timelines in light of smart-meter deployment. A draft is not itself an enacted amendment. The operative notified rules and the applicable state tariff order must therefore be checked before determining the legal position for a particular consumer.

Power Ministry of India

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4. Numerical example: calculating a ToD bill

Assume the normal tariff is ₹8 per unit, with the following illustrative rates:

The weighted average energy rate is ₹8 per unit.

If the same 350 units were all charged at the normal rate, the energy charge would also be ₹2,800. This example illustrates that time shifting does not automatically reduce the bill: savings depend on how much consumption is shifted from expensive periods into cheaper periods.

For instance, shifting 20 units from peak hours to solar hours would save ₹64 under these assumed rates:

\[ 20 \times (₹9.60-₹6.40)=₹64 \]

These figures are illustrative, not an actual electricity-board tariff. Fixed charges, demand charges, taxes, subsidies, fuel adjustments and other applicable bill components are excluded.

5. Important case laws on Time-of-Day tariffs

The following cases are particularly useful for understanding the legality, justification and limits of ToD tariffs. Some deal directly with time-based electricity pricing; others establish broader principles of tariff regulation that apply to ToD arrangements.

Case 1: Tamil Nadu Electricity Consumers’ Association v. Tamil Nadu Electricity Board

APTEL · 28 July 2011 · Appeal Nos. 192 and 206 of 2010

Source: Read the full judgment

Facts: Consumer associations challenged a Tamil Nadu tariff order, including the classification of certain periods as peak hours. They argued that the morning period from 6:00 a.m. to 9:00 a.m. had not been justified through a supporting statistical study.

Legal issue: Whether the peak-hour classification and corresponding tariff treatment were lawful.

Decision: APTEL rejected the specific challenge to the morning peak period. It noted that Regulation 11 of the Tamil Nadu Electricity Regulatory Commission's 2005 tariff regulations expressly classified 6:00–9:00 a.m. and 6:00–9:00 p.m. as peak hours, with 10:00 p.m.–5:00 a.m. designated as off-peak hours.

Indian Kanoon

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Legal principle: Where a valid regulation expressly prescribes peak and off-peak periods, the tariff classification can be upheld on that basis.

Importance for ToD tariffs: This is a directly relevant authority showing that a regulatory commission may establish different electricity rates for different times of day under its governing regulatory framework.

However, the judgment should not be read as authorising every possible peak surcharge. The validity of a different tariff structure must be assessed under the rules and regulations applicable to it.

Case 2: Polyplex Corporation Ltd. v. Uttarakhand Electricity Regulatory Commission

APTEL · 6 October 2009 · Appeal No. 85 of 2008 and I.A. No. 114 of 2008

Source: Read the judgment

Facts: The industrial consumer challenged a tariff arrangement involving multiple additional charges, including a 20% higher energy charge and ToD charges. It argued that the cumulative increase was unreasonable and insufficiently justified.

Legal issue: Whether additional electricity charges and tariff differentiation could be imposed without adequate regulatory and cost justification.

Decision and significance: The case considered the cumulative impact of the tariff structure and the consumer's objections to the charges. APTEL's discussion recognised that ToD pricing can be justified where peak demand creates shortages or higher supply costs. It also considered the need to examine the tariff structure in light of applicable law and regulatory principles.

Indian Kanoon

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Legal principle: Peak-period pricing may have a legitimate demand-management purpose, but the existence of that purpose does not automatically validate every additional charge or every cumulative tariff increase.

Importance for ToD tariffs: This case is useful when analysing whether peak pricing is a rational response to electricity-system conditions or whether a particular tariff design imposes an inadequately justified burden.

Case 3: Tata Steel Ltd. v. Orissa Electricity Regulatory Commission

APTEL · 30 May 2011 · Appeal Nos. 102, 103 and 112 of 2010

Facts and legal context: The dispute concerned the determination of electricity supply costs and the treatment of different consumer categories in tariff regulation.

Legal principle: Electricity tariff regulation must address the cost of supplying different consumer categories and the treatment of cross-subsidies. APTEL's reasoning in the related Tamil Nadu appeals referred to this judgment when directing regulatory commissions to improve cost-of-supply calculations.

Indian Kanoon

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Importance for ToD tariffs: A commission designing ToD rates should consider the relevant costs and system conditions rather than assuming that every consumer or every time period has identical supply costs.

Qualification: This is a supporting tariff-regulation authority, not a direct ruling on the validity of the nationwide ToD framework introduced in 2023.

Case 4: West Bengal Electricity Regulatory Commission v. CESC Ltd.

Supreme Court of India · (2002) 8 SCC 715

Legal significance: This case is frequently cited in discussions of electricity regulation and the role of specialist regulatory and appellate institutions. APTEL's official account refers to the Supreme Court's observations on the value of a multidisciplinary appellate body.

APPELLATE TRIBUNAL FOR ELECTRICITY

Importance for ToD tariffs: Electricity tariff disputes frequently require technical assessment of load patterns, generation costs, network constraints and regulatory design. These are matters in which specialist regulatory expertise is important.

Qualification: This case should not be cited as a direct Supreme Court approval of a particular ToD tariff or peak-hour multiplier.

Case 5: BSES Rajdhani Power Ltd. v. Delhi Electricity Regulatory Commission

APTEL · 2012 · 2012 SCC OnLine APTEL 150

Legal significance: The decision is cited for a broad understanding of electricity regulation and tariff-related terms and conditions, including billing and the method of tariff recovery.

Indian Kanoon

Importance for ToD tariffs: Time-based electricity pricing is not merely a question of selecting a rate. It also requires legally sound billing rules, metering arrangements, consumer classification and implementation procedures.

Qualification: The case supports the broader regulatory analysis rather than deciding the validity of India's 2023 ToD policy itself.

6. Judicial principles that govern ToD tariffs

Taken together, the relevant authorities support the following analytical framework.

1. Statutory authority

The tariff must be imposed by the authority empowered under the Electricity Act and the applicable regulations.

2. Rational tariff design

Peak and off-peak rates should have a legitimate connection with demand management, electricity costs or other recognised regulatory objectives.

3. Compliance with regulations

The distribution licensee must follow the applicable tariff order, approved time blocks, metering requirements and billing rules.

4. Consumer protection

Tariff determination must respect the statutory principles governing consumer interests, efficiency, cost recovery and the treatment of different consumer classes.

7. Relationship between ToD tariffs and renewable energy

ToD tariffs have become particularly significant as electricity systems incorporate larger amounts of solar and wind generation.

During periods of strong solar generation, the system may have abundant relatively low-cost electricity. After sunset, solar output declines while household and commercial demand may remain high. A tariff structure that reflects these differences can encourage consumers to shift flexible loads toward periods of greater renewable availability.

For example:

Industrial consumers may schedule eligible production processes during lower-price hours.

Electric vehicle owners may charge during designated lower-tariff periods.

Commercial buildings may pre-cool premises when electricity is cheaper.

Battery storage operators may charge and discharge according to tariff differentials, subject to applicable technical and regulatory requirements.

These responses are not automatic. Consumers need adequate price signals, suitable equipment and sufficient flexibility to change when they consume electricity.

8. How a consumer can challenge an incorrect ToD bill

A consumer who believes that a time-based charge has been wrongly applied can take the following steps.

1. Obtain the applicable tariff order. Identify the consumer category, sanctioned load or demand category, and effective date of the tariff.

2. Check the prescribed time blocks. Confirm the designated peak, normal, off-peak and solar periods, including any seasonal variations.

3. Inspect the meter data. Compare interval readings with the billing statement and identify any apparent timing or measurement error.

4. File a written complaint. Ask the distribution licensee to explain the rate applied to each time block and to correct any billing error.

5. Use the statutory grievance mechanism. If the issue remains unresolved, the consumer may approach the Consumer Grievance Redressal Forum and, where appropriate, the Electricity Ombudsman under the applicable framework.

6. Consider regulatory or appellate remedies. Where the dispute concerns the legality of a tariff order rather than an individual calculation, the available remedy and limitation period must be assessed separately.

The distinction is important: a billing error is not the same as a legal challenge to the tariff itself.

9. Critical evaluation: benefits and limitations

A further concern is distributional fairness. Households that cannot change their consumption patterns may experience higher bills without having a realistic opportunity to benefit from lower rates. Good tariff design should therefore consider affordability, consumer awareness, accessibility of smart-meter data and the needs of vulnerable consumers.

10. Conclusion

Time-of-Day tariffs are a regulatory mechanism for aligning electricity prices with the time-dependent characteristics of electricity demand and supply. In India, their legal foundation lies in the Electricity Act, 2003, the applicable consumer rules and amendments, state tariff regulations, and individual tariff orders.

The most directly relevant authority discussed above is Tamil Nadu Electricity Consumers’ Association v. Tamil Nadu Electricity Board (APTEL, 2011), which upheld the challenged peak-hour classification because it was prescribed by the governing regulation. Polyplex Corporation Ltd. provides additional context on the justification for peak pricing and the scrutiny of cumulative tariff burdens.

The central legal point is that time-based differentiation can be lawful, but the particular tariff must be authorised, properly implemented and consistent with the governing regulatory framework. The cited decisions do not constitute a blanket judicial endorsement of every ToD tariff or every surcharge.

For a dispute in a particular Indian state, the decisive documents will normally be the currently applicable state commission tariff order, the notified consumer rules and amendments, and the relevant metering and billing provisions.