India’s large industrial consumers are discovering a commercial energy option that most of their competitors have not yet fully explored: solar open access. This guide is for plant owners, energy managers and developers weighing an off-site solar PPA. Instead of waiting for rooftop space or managing a complex self-generation project, an industrial plant can buy power from an off-site solar plant through the grid, often well below what DISCOMs charge once the full charge stack is counted.
Quick answer. Solar open access in India lets commercial and industrial consumers buy power from an off-site solar plant through the grid instead of only from the DISCOM. Under the Green Energy Open Access Rules 2022, consumers with 100 kW or more of contracted load qualify, through captive, group captive or third-party PPA models. Wheeling and surcharges set the landed cost.
TL;DR
- Since the Green Energy Open Access Rules 2022, consumers with 100 kW or more of contracted load (and captive users at any size) can buy green power through open access.
- Three contractual models exist: captive (CSS exempt, needs ≥26% equity and ≥51% consumption), group captive (shared ownership) and third-party PPA (zero capex, but CSS and wheeling apply).
- Headline savings of 30-50% get diluted by a five-part cost stack: PPA tariff, wheeling/transmission charges, Cross-Subsidy Surcharge, SLDC scheduling charges, and banking/deviation settlement.
- Economics vary by state: charges set by each SERC decide how much of the gross saving survives.
- Bankable projects need PVsyst yield simulation, a grid connectivity study, CEIG electrical drawings, and STAAD Pro structural analysis before synchronization.
- Open access solar consumption also counts toward Renewable Purchase Obligation (RPO) compliance, adding value beyond the direct cost savings.
Open access is not new; it has existed in Indian electricity law since the Electricity Act 2003. What has changed is scale: open access solar has become one of the fastest-growing segments of the Indian market, led by states such as Karnataka, Maharashtra, Rajasthan, Tamil Nadu and Andhra Pradesh.
Manufacturing exporters, IT campuses, textile mills and data center operators use long-term solar PPAs to lower their power cost while their competitors keep paying rising DISCOM tariffs.
What Is Solar Open Access for an Industrial Consumer?
Open access is defined in Section 2(47) of the Electricity Act 2003 as the non-discriminatory provision of access to the transmission or distribution network to any licensee or consumer. In plain terms, it means your factory can source power from a solar park located 50 km away, using the existing grid as the delivery highway.
The industrial consumer (you) signs a Power Purchase Agreement with a solar generator or developer. The solar electricity is fed into the state or central transmission network, wheeled to your metering point, and deducted from your DISCOM bill. You pay the solar tariff (typically ₹3-5/kWh), plus applicable wheeling, transmission, and cross-subsidy surcharges, and the net effective cost is still materially below the DISCOM HT tariff.
Definition. Wheeling charges are the fees paid to the transmission or distribution licensee for using its network to wheel (transport) power from the generator to the consumer. Charges are set by the State Electricity Regulatory Commission (SERC) and commonly fall around ₹0.20 to ₹1.50/kWh depending on voltage level, distance, and state policy. Cross-Subsidy Surcharge (CSS) compensates the DISCOM for lost revenue when a consumer exits to open access; it is the most contentious charge and the primary variable that shifts whether open access is viable in a given state.
The financial logic is straightforward for high-tariff states. A Maharashtra manufacturing unit paying ₹9.5/kWh MSEDCL HT tariff versus a ₹4.5/kWh solar PPA (plus ₹1.8/kWh in wheeling, transmission, and surcharges) nets ₹3.2/kWh in savings. At 1 MW of contracted load drawing 70 lakh kWh per year, that is ₹2.24 Cr in annual savings, enough to justify the time and complexity of open access procurement.
Captive, Group Captive or Third-Party PPA: Which Open Access Model?
Indian open access solar operates through three contractual structures. Each model has a different risk-return profile, eligibility threshold, and regulatory treatment, particularly regarding which surcharges apply.
| Model | Who invests in the plant | Applicable to | Key advantage | Key constraint |
|---|---|---|---|---|
| Captive (own plant) | Consumer owns ≥26% and consumes ≥51% | Single consumer | CSS and additional surcharge waived | Requires land, significant capital, project management |
| Group Captive | Captive users together own ≥26% and consume ≥51%, in proportion to shareholding | Multiple consumers pooling demand | CSS waived; lower capital per consumer | Complex consortium governance; 26% equity requirement is strict |
| Third-Party PPA | Developer owns plant, consumer signs PPA | Any consumer above minimum load threshold | Zero capex; simplest to implement | CSS and wheeling charges apply; tariff slightly higher than captive |
Captive Model: The consumer (or a majority-owned subsidiary) owns at least 26% equity in the solar project and consumes at least 51% of the annual generation. Under Rule 3 of the Electricity Rules, 2005 and the Electricity Act, qualifying captive projects are exempt from Cross-Subsidy Surcharge and Additional Surcharge, a saving of roughly ₹1-3/kWh depending on the state. For a 10 MW industrial load committing to a 10 MW captive solar project, the economics are comparable to a rooftop system but without the constraint of rooftop space.
Group Captive Model: Multiple consumers form a legal entity (typically an SPV) to jointly own the solar plant. Together they must hold at least 26% of the equity and consume at least 51% of the generation, each in proportion to its shareholding (within a permitted variation). Governance is the main deterrent: if one member exits, the group can fail the test and CSS can apply for that year.
Third-Party PPA: This is the most commonly used model for mid-sized industrial consumers. An independent power producer or renewable energy EPC, such as Heaven Green Energy, builds and owns the solar plant; the consumer signs a long-term PPA (typically 15-25 years) to purchase power at a fixed or partially indexed rate. No equity is required. The main financial leakage is the applicable CSS and wheeling charges, which vary by state and can erode a large share of the gross saving in high-CSS states.
Field tip. Before committing to a third-party PPA, calculate the full landed cost: solar tariff + wheeling charge + transmission charge + CSS + SLDC scheduling charge + any banking charges. In Karnataka and Rajasthan, the net landed cost of open access solar is typically ₹5.5-6.5/kWh for a 2 MW consumer, still 25-35% below state DISCOM HT tariffs. In Tamil Nadu and some older CERC regulations, CSS can consume 40-60% of the savings differential.
Inter-State vs. Intra-State Open Access: Regulatory Framework
Open access operates under two regulatory frameworks depending on whether power crosses state boundaries.
Intra-State Open Access is governed by the respective State Electricity Regulatory Commission (SERC) under state-level regulations. The consumer applies to the state DISCOM or STU (State Transmission Utility) for open access permission. Approval timelines vary by state and term. The Green Energy Open Access Rules require applications through a central portal to be decided within 15 days, but long-term connectivity can still take months. Charges are set by the SERC. Most industrial open access transactions use this route because the plant and consumer are in the same state.
Inter-State Open Access is governed by CERC (Central Electricity Regulatory Commission) regulations and is applicable when power crosses state lines. The solar generator connects to the ISTS (Inter-State Transmission System) operated by PGCIL. Inter-state open access is typically used for very large consumers (above 10 MW) sourcing from distant solar resource zones (Rajasthan, Andhra Pradesh) to high-cost industrial states (Maharashtra, Tamil Nadu). Transmission charges under ISTS apply, but point-of-connection charges were rationalized in 2022 under CERC’s revised framework.
Note. The Ministry of Power's RPO trajectory notification mandates that open access consumers must fulfill Renewable Purchase Obligations. The national trajectory rises to 43.33% of consumption by FY 2029-30, and since 2023 the Energy Conservation Act obligations also cover designated consumers, including captive users. Check how your state applies it. Open access solar procurement directly satisfies these obligations, adding a compliance value on top of the cost savings.
The Open Access Cost Stack: What Industries Actually Pay
The gross cost savings from open access solar are diluted by a stack of charges. Understanding the full charge stack is the difference between a compelling business case and a disappointing out-turn. The Open Access Cost Stack Framework, the calculation sequence we use in open access feasibility work, has five components:
Solar PPA Tariff
The contracted rate with the developer or captive project. Benchmark range: ₹3.0-5.0/kWh for a 15-25 year PPA in 2025-26, depending on irradiance zone, module quality, and contract duration. Rajasthan and Andhra Pradesh sites produce the lowest tariffs; Kerala and Northeast sites are higher.
Wheeling and Transmission Charges
Paid to the STU or DISCOM for use of the grid to transport power. Range: ₹0.40-1.50/kWh for state transmission; ₹0.30-0.80/kWh for ISTS inter-state. Higher voltage connection points reduce wheeling charges significantly.
Cross-Subsidy Surcharge (CSS)
The most variable charge across states. Captive and group captive projects are CSS-exempt under Ministry of Power rules. Third-party PPA consumers pay CSS that varies widely between states, from well under ₹1/kWh to more than ₹2/kWh. Under the 2022 rules, CSS for green energy open access consumers is capped from rising more than 50% over the 12 years from when it is set. Always verify current SERC order before finalizing PPA economics.
SLDC Scheduling and System Operation Charges
State Load Dispatch Centre charges for scheduling open access power. Typically ₹0.05-0.15/kWh. Small relative to other charges but mandatory. The consumer or their scheduling agent must submit day-ahead and 15-minute injection schedules.
Banking and Deviation Settlement
When solar generation deviates from scheduled injection (due to clouds, maintenance), the imbalance is settled at deviation settlement mechanism (DSM) rates. Consumers who bank unused daytime generation for later use pay banking charges. Banking charges are set by each SERC; the 2022 rules allow at least monthly banking, with a charge to cover DISCOM costs.
State-by-State Open Access Viability: Where the Numbers Work Best
Open access solar economics vary significantly across Indian states because CSS and wheeling charges, set by SERCs, differ by policy regime. The comparison below gives indicative ranges for a 2 MW third-party PPA consumer in 2025; check each state’s current tariff and open access orders.
| State | Approx. HT Industrial Tariff | CSS + Wheeling (approx.) | Net Open Access Tariff | Net Saving |
|---|---|---|---|---|
| Karnataka | ₹8.5-9.5/kWh | ₹1.2-1.8/kWh | ₹5.0-5.8/kWh | ₹2.7-4.5/kWh |
| Rajasthan | ₹7.0-8.5/kWh | ₹0.9-1.5/kWh | ₹4.5-5.5/kWh | ₹2.5-4.0/kWh |
| Maharashtra | ₹8.5-10.5/kWh | ₹1.5-2.5/kWh | ₹5.5-7.0/kWh | ₹3.0-5.0/kWh |
| Andhra Pradesh | ₹7.5-9.0/kWh | ₹1.0-2.0/kWh | ₹5.0-6.0/kWh | ₹2.5-4.0/kWh |
| Tamil Nadu | ₹7.0-8.5/kWh | ₹2.0-3.5/kWh | ₹5.5-7.5/kWh | ₹1.5-3.0/kWh |
| Gujarat | ₹6.0-7.5/kWh | ₹1.0-1.8/kWh | ₹4.5-5.5/kWh | ₹1.5-3.0/kWh |
Note: CSS and wheeling vary by SERC order year. Always calculate against the current applicable tariff order. For the 2026 legal position by state, see our solar open access state guide. States with lower CSS and wheeling charges leave more of the saving with the consumer; high-CSS states reduce net savings for third-party PPA consumers.
Watch out. Some open access facilitators quote "solar tariff" without including CSS, wheeling, and scheduling charges in the headline number. Always ask for a full landed cost calculation before comparing open access against rooftop solar or DISCOM supply. A ₹3.5/kWh solar headline rate with ₹2.8/kWh of charges in a high-CSS state produces a landed cost of ₹6.3/kWh, potentially worse than the DISCOM rate after ToD incentives.
Engineering Requirements for Open Access Solar Plants
Open access solar parks are utility-scale generation assets, and the engineering standards that govern them are more demanding than rooftop systems. Whether you are a developer building a captive solar park for a large industrial consumer or an industrial buyer evaluating a third-party PPA, understanding the engineering deliverables that underpin bankability matters.
A utility-scale open access project connecting to the state grid requires:
- Bankable PVsyst yield simulation, P50/P75/P90 generation estimates built on Meteonorm or Solargis TMY data, with shading analysis, soiling loss, and tracker yield if applicable. Lenders and SERCs require this for PPA approval and grid connectivity study.
- Solar Ground Mount Design, Full layout with tracker or fixed-tilt configuration, table spacing, GCR calculation, access road placement, and perimeter fencing plan.
- Grid connectivity study, Required under CEA Connectivity Regulations 2019 for projects connecting to the 33 kV and above network. The study models the impact of the solar generation on grid stability at the point of connection.
- CEIG electrical drawings, State CEIG approval is mandatory before synchronization with the grid. The drawing package includes HT SLD, protection relay settings, metering configuration, earthing layout, and lightning protection design.
- STAAD Pro structural analysis, Wind load calculations per IS 875 Part 3 for the mounting structure, including pile embedment depth and section sizing. Required by lenders for project financing.
Evaluating an open access project? See the engineering deliverables first.
Download a sample ground-mount design pack, PVsyst report, layout drawing, SLD, and BOQ, for a 10 MW open access project.
Get the sample pack →Open Access Solar Market Trends
The open access solar segment in India has entered a new growth phase. According to Mercom India’s open access tracker for 2024, open access is among the fastest-growing parts of the Indian solar market, with Karnataka, Rajasthan and Maharashtra among the leading states. Check the latest tracker for current capacity figures.
According to IEA’s Renewables 2024 report, India is one of the fastest-growing renewable markets, and commercial and industrial procurement, including open access, is a growing share of deployment. Our India solar market outlook tracks the latest numbers.
Key adoption drivers:
- C&I tariff escalation: State DISCOM HT tariffs have risen in most major industrial states in recent years. Every tariff hike increases the absolute saving from open access solar.
- RPO obligation tightening: The Ministry of Power’s Renewable Purchase Obligation trajectory to FY 2029-30 mandates steadily rising RE percentages from industrial consumers. Open access solar is often the cheapest way to meet it.
- Green procurement pressure from buyers: Manufacturing exporters supplying to European and American brands face Scope 2 emission disclosure requirements. Open access RE certificates (RECs or I-RECs) satisfy green procurement audits without the capital cost of captive solar.
- Simpler access rules: the 2022 Green Energy Open Access Rules lowered the load threshold to 100 kW and set up a central application portal with fixed approval timelines. Our state guide to solar open access in 2026 shows how far each state has implemented them.
100 kW
Minimum load for green open access (2022 rules)
Green Energy Open Access Rules, 2022
₹3-5
Typical solar PPA tariff per kWh
Indicative 2025 range, before charges
43.33%
RPO trajectory by FY 2029-30
Ministry of Power RPO trajectory
25 years
Typical PPA Duration
Industry standard
Open Access vs. Rooftop Solar: Choosing the Right Strategy
For an industrial consumer evaluating renewable energy procurement, the choice between rooftop solar and open access solar is not binary; many large plants use both. The decision depends on available rooftop area, load profile, capital appetite, and state regulatory environment.
ROOFTOP SOLAR, BEST FOR
- Plants with large, unshaded roof area (5,000+ sqm per MW)
- Medium-sized consumers where open access approval is slow in their state
- States with favorable net-metering and banking provisions
- Industries that want asset ownership and accelerated depreciation benefit
OPEN ACCESS, BEST FOR
- Large consumers (1 MW+) with limited rooftop space
- Multi-site industrial groups wanting centralized RE procurement
- Companies avoiding capital deployment in non-core assets
- Industries in high-CSS states where captive model waives most charges
Verdict. Open access solar delivers the largest absolute cost savings for large industrial consumers in high-tariff states, particularly under captive or group captive structures where CSS is waived. Rooftop solar offers faster approvals, lower regulatory complexity, and accelerated depreciation benefits for mid-sized industrials. For any plant above 2 MW total power consumption, the economics of open access warrant a formal feasibility study before defaulting to rooftop-only strategy.
How Heaven Designs Supports Open Access Solar Projects
Engineering accuracy is the foundation of bankable open access solar. A yield simulation that overestimates generation by 8% invalidates the PPA economics. A grid connectivity study that misses a protection coordination issue triggers months of delay from the STU. Heaven Designs provides the full engineering stack for open access projects, from pre-feasibility through CEIG approval.
- Solar Ground Mount Design, Full IFC-grade layout, tracker or fixed-tilt configuration, GCR optimization, access roads, and perimeter plan for 10-100 MW open access projects.
- Site Survey and Land Feasibility, Land suitability assessment, grid proximity study, irradiance mapping using Meteonorm/Solargis, and sub-station capacity availability check.
- MW-Scale PMC, Owner’s engineer services for industrial buyers sourcing captive solar parks, from developer selection through commissioning milestone verification.
- Electrical CEIG Drawings, State CEIG approval-format HT drawings, protection relay settings, and synchronization schemes for plants connecting to 33 kV and 110 kV state transmission networks.
- Solar Civil and Structural Engineering, STAAD Pro structural analysis reports for mounting structures per IS 875 Part 3 wind load and seismic zone requirements, required by lenders and state grid authorities.
- Download a sample deliverable, Access a redacted engineering pack for a 10 MW ground-mount open access project before briefing your design partner.
Contact us for a project-specific open access feasibility study and engineering scope estimate.
FAQ
What is the minimum load required to use open access solar in India?
Under the Electricity (Promoting Renewable Energy Through Green Energy Open Access) Rules, 2022, the threshold for green energy open access is 100 kW of contracted demand or sanctioned load, which can be aggregated across connections in the same electricity division. Captive consumers have no minimum. Conventional open access under older state rules often required 1 MW.
States have adopted the 2022 rules at different speeds. Confirm the applicable threshold with the state DISCOM or SERC before initiating an open access application.
How long does open access approval take in India?
Timeline varies significantly by state and project type. The 2022 rules require green energy open access applications to be decided within 15 days through the central portal. A new plant still needs grid connectivity, protection studies and state approvals, which can take several months to over a year depending on the STU’s queue and the voltage level.
What is the difference between open access and net metering?
Net metering applies to consumers with on-site rooftop solar generation. The consumer generates power on their own premises, uses what they can, and exports surplus to the grid, which is credited under the state’s net metering rules.
Open access applies to off-site generation: the consumer buys power from a third-party solar plant located elsewhere and has it wheeled through the grid to their meter. Net metering is simpler and does not involve wheeling charges; open access involves more regulatory steps but can provide much larger volumes of renewable energy than a rooftop system allows.
Are there risks to signing a 25-year open access PPA?
Yes. The primary risks are: (1) CSS and regulatory charges may increase over the PPA term if the state SERC revises tariff orders; (2) the solar developer may default on generation commitments if the plant underperforms; (3) grid connectivity rules may change, affecting wheeling charges.
Mitigants include regulatory pass-through clauses in the PPA (sharing risk of regulatory charge changes between consumer and developer), verifying the developer’s financial strength and plant engineering quality, and capping maximum CSS exposure in the contract.
Do open access consumers need to manage scheduling and dispatch?
Yes. Open access consumers must submit day-ahead injection schedules to the SLDC (State Load Dispatch Centre) through a scheduling agent (typically the developer or a licensed third party). Deviations between scheduled and actual injection are settled at DSM (Deviation Settlement Mechanism) rates.
For solar-specific open access, the developer typically manages scheduling as part of the PPA services. Consumers with multiple open access contracts should verify that a single scheduling agent manages all contracts to minimize coordination risk and DSM charges.
How does open access solar satisfy RPO obligations?
Power consumed through a long-term open access PPA from a solar developer qualifies as renewable energy consumption for RPO purposes. The consumer can claim these units as RE in their RPO compliance filing with the state SERC. For additional flexibility, the developer can issue RECs (Renewable Energy Certificates) if the power is not consumed directly under an open access arrangement, though RECs at ₹1.5-2.5/kWh add to the effective cost.
Most large industrial consumers pursuing open access for cost savings find that direct consumption under a PPA is more economical than buying RECs separately.