Quick Facts
What open access is
Open access is the right of a large electricity consumer to buy power directly from a generator of their choice, using the transmission and distribution networks owned by central, state, or private utilities. The mechanism is established under Section 42 of the Electricity Act 2003 and operationalised through CERC regulations (inter-state open access) and SERC regulations (intra-state open access).
For solar, open access enables commercial and industrial (C&I) consumers to procure clean power through long-term contracts with utility-scale solar developers. Instead of buying all their electricity from the local DISCOM, the consumer signs a PPA with an independent solar developer. The DISCOM continues to provide standby capacity, billing for residual consumption, and grid services, but the bulk of the energy comes from the open-access supplier.
Open access has become one of India’s largest renewable energy growth drivers. Corporate solar through open access now totals several gigawatts of installed capacity, with new contracts adding 3 to 5 GW annually as of 2026.
How open access works
The mechanics involve five steps.
The consumer assesses eligibility under the relevant state’s open-access regulations. Eligibility usually depends on contract demand or sanctioned load.
The consumer selects a solar developer (or developer consortium) and negotiates a long-term PPA, typically 15 to 25 years.
The developer secures land, evacuation infrastructure, and project financing. The plant is built and connected to the grid.
The developer files open-access applications with SLDCs, DISCOMs, and CERC (for inter-state) or SERC (for intra-state). Various charges and conditions are settled.
Power flows from the solar plant to the consumer through the grid. The consumer pays the developer the contracted tariff per kWh plus pays the DISCOM all applicable open-access charges.
The metering is typically on a 15-minute time block basis, with energy balancing rules defined in the regulations.
Charges under open access
Open access involves multiple charges beyond the contracted tariff with the developer.
Transmission charges: For using the inter-state transmission system (ISTS) or state transmission utility (STU) network. Set by CERC for ISTS and SERC for STU. Typically Rs 0.30 to Rs 1.00 per kWh.
Wheeling charges: For using the distribution network of the DISCOM. Set by SERC. Typically Rs 0.30 to Rs 1.20 per kWh.
Cross-subsidy surcharge (CSS): Compensation to the DISCOM for revenue lost from open-access consumers (who would otherwise pay the higher residential and agricultural cross-subsidy). Set by SERC, often the largest single charge.
Additional surcharge: Some states levy this for stranded power purchase contracts of the DISCOM.
Standby charges: For maintaining backup capacity at the DISCOM for the open-access consumer.
Losses: Distribution losses applied to power flowing through the network.
All these charges are deducted from the gross savings. Net savings to the consumer are still typically 25% to 45% versus grid tariffs.
ISTS waiver for renewable open access
The Government of India has waived ISTS transmission charges for solar and wind generators commissioned by certain deadlines (initially 30 June 2025, with various extensions). This significantly improves the economics of inter-state renewable open access.
The waiver was introduced in 2021 to accelerate renewable adoption. It applies to inter-state transmission charges only; intra-state charges (wheeling, CSS) continue to apply at the state level.
Open access compared to group captive
Group captive is an alternative mechanism where the consumer holds at least 26% equity in the generating company and consumes at least 51% of the plant’s output. Cross-subsidy surcharge does not apply to group captive in most states, making it economically attractive for consumers in states with high CSS.
| Feature | Open Access | Group Captive |
|---|---|---|
| Equity stake | None required | At least 26% by consumer |
| Cross-subsidy surcharge | Applicable | Generally exempt |
| Energy consumption rule | None specific | At least 51% by captive group |
| Contract structure | PPA | Equity plus consumption agreement |
| Best for | Consumers in low-CSS states | Consumers in high-CSS states |
The choice depends on state CSS rates, consumer’s willingness to take equity, and contract simplicity.
State-by-state open access landscape
Maharashtra, Karnataka, Tamil Nadu, Andhra Pradesh, and Gujarat are among the most active open-access markets, with strong industrial demand and competitive solar developers.
Some states (notably Punjab, Haryana) have applied policy restrictions on open access during specific periods, citing DISCOM revenue concerns. CERC and APTEL have intervened to enforce open-access rights in several cases.
Rajasthan and Madhya Pradesh have favourable open-access policies for renewables, including ISTS-waived projects.
The regulatory environment continues to evolve. Tracking the latest SERC orders and DISCOM circulars is essential before committing to long-term contracts.
Open access for solar specifically
For solar, the open-access model has clear advantages over alternative structures.
Long-term price hedge. Solar PPAs lock in tariffs for 20 to 25 years, while grid tariffs typically rise 3% to 5% annually.
RPO compliance. Power procured from renewable sources through open access counts toward the consumer’s RPO obligation.
Carbon and ESG goals. Open-access solar contracts often serve dual purposes of cost reduction and emissions reduction.
Scale economy. Open-access solar plants are typically 10 MW to 200 MW, much larger than on-site rooftop, achieving lower per-Wp CAPEX and tariffs.
Multi-site supply. A single open-access PPA can supply power to multiple consumer facilities through the grid, simplifying procurement for distributed operations.
Typical open-access solar tariffs in 2026
| State | Solar Tariff (Rs/kWh, all-in for consumer including charges) | Effective Discount vs Retail |
|---|---|---|
| Maharashtra | 4.5 to 5.5 | 30% to 40% |
| Karnataka | 4.2 to 5.2 | 25% to 35% |
| Tamil Nadu | 4.5 to 5.8 | 30% to 40% |
| Gujarat | 4.0 to 5.0 | 25% to 35% |
| Andhra Pradesh | 4.0 to 5.0 | 25% to 35% |
| Rajasthan | 3.5 to 4.5 | 30% to 40% |
| Madhya Pradesh | 3.8 to 4.8 | 25% to 35% |
These are all-in tariffs to the consumer including the PPA tariff plus all open-access charges. Comparable C&I grid tariffs are typically Rs 8 to Rs 12 per kWh.
Common mistakes with open access
Underestimating the regulatory complexity. CSS, wheeling, transmission, and standby charges vary by state and can change.
Choosing the lowest PPA tariff without analysing total landed cost including all charges.
Locking into long-term PPAs without verifying developer financial strength. A developer default in year 5 of a 25-year contract is a serious risk.
Forgetting standby capacity. Even with open-access solar covering 70% to 80% of load, the DISCOM standby charge continues.
Ignoring grid imbalance charges. Solar output varies; the consumer’s actual demand also varies. Imbalances are billed under deviation settlement mechanism.
Not considering hybrid solar plus wind plus battery for higher availability factor.
Best practices
Run a detailed financial model with realistic open-access charges before signing any PPA.
Diversify across multiple developers if the open-access solar volume is large.
Include in the PPA: tariff escalation (if any), force majeure, change-in-law protection, performance guarantees, and termination clauses.
Engage with the state SERC processes when open-access regulations are being revised.
Consider hybrid solar plus storage or solar plus wind for round-the-clock supply.
For very large consumers, evaluate group captive against open access on a total cost basis.
Standards and references
Open access is established under Section 42 of the Electricity Act 2003. Inter-state open access is regulated by the CERC (Open Access in Inter-State Transmission) Regulations. Intra-state open access is regulated by state-specific SERC orders. The Ministry of Power has issued various clarifications and amendments over time, accelerating policy clarity.
Related glossary terms
- Power Purchase Agreement
- Renewable Energy Certificate
- Renewable Purchase Obligation
- Group Captive Model
- Wheeling Charges
- Cross-Subsidy Surcharge
- DISCOM
- ISTS Charges
- CERC
- SERC
Key takeaways
Open access allows large electricity consumers in India to buy power directly from generators using the transmission and distribution network. For solar, open access is the primary mechanism by which C&I consumers source long-term clean power at fixed tariffs, typically saving 25% to 45% versus grid rates. Charges include transmission, wheeling, cross-subsidy surcharge, and standby; net savings remain substantial. The mechanism is regulated by CERC for inter-state and SERCs for intra-state, with policies that vary across states and continue to evolve.