Quick Facts
What intra-state and inter-state mean
The Indian electricity system has a fundamental distinction:
Intra-state: Generation and consumption within a single state. Uses the state transmission utility (STU) network. Regulated by the state’s SERC.
Inter-state: Generation in one state, consumption in another. Uses the inter-state transmission system (ISTS) operated by Power Grid Corporation. Regulated by CERC.
For solar projects, this classification determines:
Which regulator approves tariffs and PPAs.
Which charges apply (ISTS for inter-state, STU for intra-state, plus DISCOM wheeling and CSS).
Which approvals are needed.
Which auction or procurement processes are accessible.
Intra-state solar
Intra-state solar projects are connected to the state’s electricity network (STU or DISCOM) and sell power within the state:
Tariff: Set by state SERC orders or discovered through state tenders.
Approvals: Through state agencies (SERC, STU, DISCOM, State Nodal Agency).
Charges: STU wheeling, DISCOM wheeling, cross-subsidy surcharge (state-specific).
Procurement: Through state DISCOM tenders (typical) or open access.
Net metering: Within the state, governed by state SERC’s net metering regulation.
Examples:
A rooftop solar system on a Mumbai residential building selling export to MSEDCL.
A 5 MW ground-mount plant in Gujarat selling power to GUVNL.
A commercial customer in Karnataka using open access to buy from a Karnataka solar developer.
A residential rooftop in Tamil Nadu under PM Surya Ghar net metering.
For intra-state solar, the regulatory environment is established and predictable. Each state has its own framework, but within the state the rules are clear.
Inter-state solar
Inter-state solar projects use the inter-state transmission system to move power across state boundaries:
Tariff: Set by CERC framework or SECI auction.
Approvals: Through CERC, Power Grid, and the relevant state agencies in destination state.
Charges: ISTS (currently waived for renewables), destination-state wheeling, cross-subsidy surcharge in destination state.
Procurement: Through SECI tenders, NTPC tenders, or specific inter-state PPAs.
Net metering: Generally not applicable; inter-state transactions are wholesale arrangements.
Examples:
A 100 MW solar plant in Rajasthan supplying power to NTPC for delivery to Maharashtra.
A 50 MW ground-mount in Gujarat with PPA to a Karnataka utility.
A SECI-procured power flowing from a Rajasthan plant to a Tamil Nadu DISCOM.
An open-access corporate solar deal: solar plant in Andhra Pradesh, consumer in Karnataka.
For inter-state solar, the central government (Ministry of Power, CERC) provides the framework. The ISTS waiver has been a major policy support for inter-state renewables.
Regulatory framework
| Aspect | Intra-State | Inter-State |
|---|---|---|
| Tariff regulator | State SERC | CERC |
| Open access regulation | SERC | CERC |
| Network operator | State STU | Power Grid (CTU) |
| Major charges | STU + DISCOM wheeling + state CSS | ISTS (waived) + destination state charges |
| PPA approval | SERC | CERC |
| Net metering | SERC orders | Not applicable (wholesale) |
| Major tender source | State DISCOM tenders | SECI, NTPC tenders |
| Banking provisions | SERC orders | Limited inter-state banking |
The fragmentation creates regulatory complexity but also flexibility. Different projects choose different paths based on best fit.
Economic differences
For solar developers and consumers, the economic implications:
Tariff levels: SECI-procured inter-state tariffs are often lower than state-specific (competitive auction effects). However, ISTS charges (when applied) eat into the difference.
Charges: Intra-state often has simpler charge structures. Inter-state involves multiple jurisdictions.
Risk: Intra-state has DISCOM-level credit risk (state DISCOMs vary in financial strength). Inter-state with SECI has sovereign-backed offtake credit.
Market size: Intra-state limited to state market. Inter-state accesses the national market.
Procurement flexibility: Inter-state offers more procurement options (SECI, NTPC, corporate). Intra-state mostly state DISCOM procurement.
For utility-scale developers, inter-state via SECI is often preferred for credit quality. For C&I corporate consumers, intra-state often simpler and cheaper unless ISTS waiver makes inter-state attractive.
ISTS waiver impact
The Government’s ISTS waiver for solar and wind has significantly tilted economics toward inter-state for many projects:
Pre-waiver: Inter-state was expensive due to 0.50 to 1.50 per kWh ISTS charges.
Post-waiver: Inter-state economics improved substantially.
Corporate open-access deals across states have grown rapidly under the waiver.
Without waiver, intra-state would be more economical for most C&I.
The waiver eligibility depends on commissioning date. Projects commissioned within the waiver window benefit for their PPA term.
Operational differences
Inter-state operations:
ABT meter required at substation.
15-minute scheduling and settlement.
Coordination with Regional Load Dispatch Centre (RLDC).
Compliance with grid code for inter-state generators.
Standby capacity and reserve margins.
Intra-state operations:
Trivector or net-metering meter typical.
Daily or monthly settlement.
Coordination with State Load Dispatch Centre (SLDC).
Compliance with state grid code.
Standby with state DISCOM.
For utility-scale plants, inter-state operations are more complex but well-established. Intra-state operations are simpler.
Common mistakes regarding intra vs inter-state
Treating them as interchangeable. Different regulators, different procedures, different economics.
Forgetting ISTS waiver eligibility. Projects must commission within the waiver window to benefit.
Mismatching procurement and grid connection. Procurement from SECI requires inter-state grid connection.
Ignoring destination-state charges. Even with ISTS waiver, destination state charges (wheeling, CSS) still apply.
Not aligning approvals with connection. Inter-state CERC approval is required even when destination state’s DISCOM is involved.
Best practices
For utility-scale solar developers, evaluate both intra-state and inter-state options.
For corporate open-access deals, model both intra-state and inter-state with current ISTS waiver status.
For SECI auctions, plan for inter-state grid connection and ABT metering.
For state DISCOM tenders, focus on intra-state grid connection.
For lender’s diligence, the regulatory framework (intra vs inter-state) is a key parameter.
For long-term planning, consider how ISTS waiver duration affects inter-state economics.
Standards and references
Intra-state and inter-state distinctions follow the Electricity Act 2003. Inter-state matters are governed by CERC. Intra-state matters by state SERCs. The Forum of Regulators coordinates across both. Specific procedures vary by state.
Related glossary terms
Key takeaways
Intra-state solar projects generate and sell power within a single state through the state transmission utility (STU). Inter-state solar projects sell across state boundaries through the inter-state transmission system (ISTS) operated by Power Grid. The two categories have different regulatory frameworks: state SERCs govern intra-state; CERC governs inter-state. Different charges, procurement processes, and operational requirements apply. The ISTS waiver for solar and wind has significantly improved inter-state project economics. For utility-scale solar, inter-state via SECI is often preferred for credit quality; for corporate open-access deals, both options should be evaluated.