Key Takeaways
- Open access solar allows large industrial consumers (typically 1 MW+ contracted demand) to procure solar power from off-site plants, bypassing rooftop limitations.
- The effective cost of open access solar ranges from ₹4.5–7.0 per unit (including transmission charges and cross-subsidy surcharge), still 30–50% cheaper than industrial grid tariffs.
- Group captive is the most popular model — you invest 26% equity in a solar plant and enjoy a 100% waiver on cross-subsidy surcharge.
- Open access is ideal for factories with limited roof space, high power demand, or multiple facilities that can aggregate consumption.
- Sun Wave Technologies helps industrial clients navigate open access regulations and secure cost-effective power procurement across North India.
What Is Open Access Solar?
Open access solar allows industrial electricity consumers to purchase solar power from a generator located anywhere in the same state (or sometimes across states) through the existing transmission and distribution network. Unlike rooftop solar that requires panels on your building, open access solar can be generated at a remote solar farm.
Think of it as buying solar electricity the same way you buy grid electricity — through the transmission network — but at a lower cost and with green energy benefits.
Who Is Eligible for Open Access Solar?
Eligibility varies by state, but the general criteria are:
| Parameter | Typical Requirement |
|---|---|
| Minimum contracted demand | 1 MW (some states: 500 kW or 100 kW) |
| Connection type | HT (High Tension) — 11 kV or above |
| Electricity category | Industrial, commercial, or institutional |
| Payment history | No outstanding dues with DISCOM |
Key point: If your factory's connected load is below 1 MW, rooftop solar with net metering is the better option. Open access becomes advantageous for larger consumers.
Types of Open Access Solar
1. Group Captive Model (Most Popular)
In a group captive arrangement, the industrial consumer invests 26% of the equity in the solar power plant and commits to purchasing at least 51% of the electricity generated.
How it works:
- A solar developer builds a 5–50 MW solar plant
- Multiple industrial consumers invest 26% equity proportional to their power share
- Consumers purchase electricity at a pre-agreed PPA rate
- Key benefit: 100% waiver on cross-subsidy surcharge (CSS), saving ₹1–2.5/kWh
Economics:
- Solar PPA rate: ₹3.0–4.0/kWh
- Transmission charges: ₹0.5–1.5/kWh
- Cross-subsidy surcharge: ₹0 (waived for group captive)
- Additional surcharge: ₹0.5–1.0/kWh
- Total cost: ₹4.0–6.5/kWh
Compared to grid tariffs of ₹8–13/kWh, that's a savings of 35–55%.
2. Third-Party Open Access
In this model, you simply purchase solar electricity from a developer without any equity investment. It's simpler but slightly more expensive due to cross-subsidy surcharge.
How it works:
- A solar developer generates electricity
- You sign a PPA to purchase a fixed quantity at an agreed rate
- Electricity is wheeled through the DISCOM/transmission network to your factory
Economics:
- Solar PPA rate: ₹3.0–4.0/kWh
- Transmission charges: ₹0.5–1.5/kWh
- Cross-subsidy surcharge: ₹1.0–2.5/kWh (this is the main disadvantage)
- Additional surcharge: ₹0.5–1.0/kWh
- Total cost: ₹5.0–9.0/kWh
The economics are state-dependent. In high-CSS states, third-party open access may not save much. In states with lower CSS (like Gujarat, Rajasthan), it's viable.
3. Bilateral Open Access
Direct arrangement between generator and consumer, typically for very large consumers (5 MW+). Requires regulatory approvals from the State Electricity Regulatory Commission (SERC).
Comparison of Open Access Models
| Factor | Group Captive | Third-Party | Bilateral |
|---|---|---|---|
| Equity investment | 26% required | None | None |
| Cross-subsidy surcharge | Waived (0%) | Full (₹1–2.5/kWh) | Full or partial |
| Minimum size | 1 MW share | 1 MW | 5 MW+ |
| PPA flexibility | Locked with plant | Can change developers | Highly customizable |
| Setup complexity | Medium | Low | High |
| Best for | Cost-conscious buyers | Quick procurement | Very large consumers |
State-Wise Open Access Solar Economics
Haryana Open Access Solar
- Minimum eligible demand: 1 MW
- Cross-subsidy surcharge (CSS): ₹1.85/kWh (HT industrial)
- Transmission charges (IntraST): ₹0.77/kWh
- Additional surcharge: ₹0.91/kWh
- Wheeling charges: ₹0.37/kWh
- Total open access charges: ₹3.90/kWh
- Solar PPA rate: ₹3.0–3.5/kWh
- All-in cost: ₹6.9–7.4/kWh
- Grid tariff: ₹8.5–10/kWh
- Savings: 15–30%
- Group captive advantage: CSS waiver saves ₹1.85/kWh, bringing all-in cost to ₹5.0–5.5/kWh
Rajasthan Open Access Solar
- Minimum eligible demand: 1 MW (500 kW for solar specifically)
- CSS: ₹1.15/kWh
- Transmission charges: ₹0.63/kWh
- All-in cost (group captive): ₹4.5–5.5/kWh
- Grid tariff: ₹7.5–9.0/kWh
- Savings: 30–45%
Rajasthan offers some of the best open access economics in India due to low CSS and excellent solar irradiance.
Gujarat Open Access Solar
- Minimum eligible demand: 1 MW
- CSS: ₹0.87/kWh (lowest among major states)
- Transmission charges: ₹0.55/kWh
- All-in cost (third-party): ₹4.5–6.0/kWh
- Grid tariff: ₹7.5–8.5/kWh
- Savings: 25–40%
Gujarat's low CSS makes even third-party open access viable without group captive investment.
Maharashtra Open Access Solar
- Minimum eligible demand: 1 MW
- CSS: ₹2.39/kWh (highest among major states)
- Transmission charges: ₹1.08/kWh
- All-in cost (group captive): ₹5.0–6.5/kWh
- Grid tariff: ₹10–13/kWh
- Savings: 35–55%
Despite high CSS, Maharashtra's even higher grid tariffs make open access solar highly attractive, especially in the group captive model.
Open Access vs. Rooftop Solar: Which Is Right for You?
| Factor | Open Access Solar | Rooftop Solar |
|---|---|---|
| Location of panels | Off-site (developer's land) | On your rooftop |
| Your investment (CAPEX) | 26% equity (group captive) or ₹0 (PPA) | Full EPC cost or ₹0 (RESCO) |
| Capacity limit | No limit (can procure MW-scale) | Limited by roof area |
| Transmission charges | ₹0.5–1.5/kWh | None |
| Cross-subsidy surcharge | ₹0–2.5/kWh | None |
| Effective cost per unit | ₹4.5–7.0 | ₹2.5–5.5 |
| Maintenance responsibility | Developer | You (CAPEX) or developer (RESCO) |
| Best for | Large consumers (1 MW+) with limited roof | All sizes with adequate roof space |
The best strategy for large consumers: Install maximum rooftop solar first (cheapest per unit), then supplement with open access for additional requirement.
How to Procure Open Access Solar: Step by Step
Step 1: Assess Your Eligibility and Requirement
- Confirm your contracted demand exceeds the state minimum (usually 1 MW)
- Calculate the quantum of open access power needed (total consumption minus rooftop solar)
- Decide between group captive and third-party based on investment appetite
Step 2: Find a Solar Developer
Look for developers with:
- Operational solar plants in your state or adjacent state
- Available capacity for new consumers
- Competitive PPA rates with transparent escalation clauses
- Track record of reliable generation and billing
Step 3: Negotiate the PPA
Key terms to negotiate:
- PPA rate: Target ₹3.0–3.5/kWh for new solar (2025 rates)
- Escalation: 0–2% annual escalation (lower is better; grid tariffs rise 5–7%)
- Tenure: 15–25 years
- Minimum offtake: Negotiate flexibility for seasonal variations in your consumption
- Banking: Some states allow monthly or seasonal banking of excess units
Step 4: Apply for Open Access Permission
- Submit application to State Load Dispatch Centre (SLDC) for long-term open access
- Or apply through DISCOM for short-term or medium-term open access
- Timeline: 30–90 days depending on state and type of open access
Step 5: Set Up Metering and Billing
- Install special energy meters for open access accounting
- Set up energy scheduling with the SLDC
- Coordinate billing with DISCOM (grid charges) and developer (PPA charges)
Real-World Economics: Open Access Solar Case Study
Large Manufacturer in Manesar, Haryana (3 MW demand)
Current situation:
- Connected demand: 3 MW
- Monthly consumption: 12 lakh units
- Grid tariff: ₹9.2/kWh
- Monthly electricity bill: ₹1.1 Crore
Solution: 2 MW Group Captive Solar + 500 kW Rooftop
| Component | Capacity | Cost per Unit | Monthly Units | Monthly Cost |
|---|---|---|---|---|
| Rooftop solar | 500 kW | ₹0 (owned, post-payback) | 65,000 | ₹0 |
| Group captive OA | 2 MW | ₹5.2/kWh (all-in) | 5,20,000 | ₹27 lakhs |
| Grid (balance) | Variable | ₹9.2/kWh | 4,15,000 | ₹38 lakhs |
| Total | — | — | 12,00,000 | ₹65 lakhs |
Monthly savings: ₹45 lakhs (41% reduction) Annual savings: ₹5.4 Crore
Challenges and Risks in Open Access Solar
Regulatory Uncertainty
State electricity regulatory commissions periodically revise open access charges. CSS and additional surcharge can increase, reducing savings. Mitigation: Long-term open access agreements typically lock in charges for the agreement period.
Banking Restrictions
Some states limit or don't allow energy banking (carrying forward excess units to the next month). This means if your consumption is lower than generation in a given period, you may lose units. Mitigation: Accurate demand forecasting and scheduling.
Deviation Charges
If the actual solar generation deviates significantly from the scheduled quantum, deviation settlement charges apply. Mitigation: Work with developers who have accurate generation forecasting capabilities.
Counter-Party Risk
In group captive, if other equity partners exit, the financial structure changes. Mitigation: Work with reputed developers and ensure the shareholder agreement has clear exit and entry provisions.
Frequently Asked Questions
What is the minimum load required for open access solar in India?
The minimum contracted demand for open access solar varies by state. In most major industrial states, it's 1 MW. However, Rajasthan allows open access for solar at 500 kW, and some states are reducing the threshold further. For factories below the open access threshold, rooftop solar with net metering is the recommended alternative.
What is the difference between group captive and third-party open access?
In group captive, you invest 26% equity in the solar plant and consume at least 51% of its output — in return, you get a 100% waiver on cross-subsidy surcharge (saving ₹1–2.5/kWh). In third-party open access, you simply buy power without equity investment but pay the full CSS. Group captive costs ₹4–6.5/kWh all-in, while third-party costs ₹5–9/kWh depending on the state.
Can I combine open access solar with rooftop solar?
Absolutely. This is the recommended approach for large consumers. Install maximum rooftop solar first (it's the cheapest at ₹2.5–3.5/kWh LCOE with no transmission charges), then procure additional solar through open access for your remaining demand. Sun Wave Technologies can design a comprehensive solution combining both rooftop EPC and open access procurement.
How much can I save with open access solar compared to grid tariff?
Savings depend on your state's grid tariff and open access charges. In the group captive model, typical savings range from 30–55% of grid tariff. In third-party model, savings range from 15–35%. For a factory consuming 10 lakh units per month at ₹9.5/kWh grid tariff, group captive open access solar can save ₹3–5 Crore per year.
Is open access solar reliable? What happens on cloudy days?
Open access solar has the same weather dependency as any solar system — generation drops during cloudy or rainy periods. The difference is that your DISCOM automatically supplies the shortfall from the grid. You pay grid tariff for the grid units and PPA rate for the solar units. Over a year, solar typically delivers 90–95% of the scheduled generation, with seasonal variations.
What are the tax benefits of group captive solar?
In a group captive arrangement, your 26% equity investment qualifies for accelerated depreciation (40% in year 1), which creates a tax shield of approximately 25–30% of your investment. Additionally, the solar PPA rate is treated as an operating expense, fully deductible from business income. The combination of tax benefits and lower electricity costs makes group captive one of the most attractive solar procurement options for profitable companies.
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