SolarCalculatorsSolar CAPEX vs OPEX (RESCO) Models in India: Commercial & Industrial (C&I) PPA Guide 2026
1. Understanding the Core Business Models
Indian C&I consumers pay the highest electricity tariffs in the world—often between ₹8.50 and ₹12.50 per unit—subsidizing the agricultural and domestic sectors. Solar energy can be procured under three primary legal frameworks:
| Criteria | CAPEX Model (Outright Ownership) | OPEX / RESCO Model (BOOT / PPA) | Solar Lease / Deferred CAPEX |
|---|---|---|---|
| Upfront Capital Required | 100% paid by factory/building owner | ₹0 (Zero CAPEX) by consumer | 10% - 20% down payment |
| Asset Ownership | Client owns asset from Day 1 | RESCO developer owns system for 15–25 yrs | Financier holds title until EMI completes |
| Electricity Cost | Free power after payback (~₹1.80/kWh LCOE) | Pre-agreed PPA tariff (e.g. ₹4.20–₹5.50/kWh) | Fixed monthly lease rental |
| Tax Depreciation Benefit | 40% Accelerated Depreciation claimed by client | Claimed by the RESCO developer | Claimed by lessor or lessee based on contract |
| O&M & Generation Risk | Borne by client (can contract via AMC) | 100% borne by RESCO developer | Shared or handled by AMC partner |
| Typical Payback / Term | 2.8 – 3.8 years complete capital recovery | 15 – 25 year Power Purchase Agreement | 5 – 7 year loan/lease amortisation |
2. Detailed Cash Flow Modeling: 500 kWp Factory Installation
Let us compare the 15-year cumulative cash flow for a manufacturing unit in Pune, Maharashtra, installing a 500 kWp rooftop solar plant. The facility pays an average DISCOM grid tariff of ₹9.50/kWh with an annual escalation of 3%.
| Financial Parameter | CAPEX Model (₹ Lakhs) | OPEX / RESCO Model (PPA) |
|---|---|---|
| Initial Turnkey Capex | ₹195.00 Lakhs | ₹0.00 |
| Year 1 Tax Shield (40% Dep. @ 25% Corp Tax) | ₹19.50 Lakhs (Direct cash savings) | Nil |
| Year 1 Generation (700,000 units) | 700,000 kWh | 700,000 kWh |
| Year 1 Grid Value Displaced (@ ₹9.50) | ₹66.50 Lakhs gross savings | ₹66.50 Lakhs baseline value |
| Payment to RESCO (@ ₹4.50 PPA Tariff) | ₹0.00 | ₹31.50 Lakhs paid to developer |
| Net Year 1 Operational Savings | ₹61.50 Lakhs (net of ₹5L O&M) | ₹35.00 Lakhs |
| Simple Payback Period | 3.17 Years | Immediate (Day 1 Positive Cash Flow) |
| 15-Year Cumulative Net Profit | ₹820+ Lakhs | ₹510+ Lakhs |
3. Key Clauses in a Commercial RESCO PPA Agreement
If opting for the OPEX model, your legal counsel must meticulously review these four clauses before signing the 20-year Power Purchase Agreement:
- Minimum Guaranteed Generation (MGG): The developer must guarantee a minimum generation benchmark (typically 1,350 to 1,450 kWh per kWp annually). If generation falls short due to inverter failure or module soiling, the developer must credit the difference at the full DISCOM tariff.
- Tariff Escalation Clause: Ensure the PPA offers either a Flat Levelized Tariff (e.g., ₹4.75/unit flat for 20 years) or a modest fixed escalation not exceeding 1.5% to 2.5% per annum. Beware of contracts indexing tariffs to DISCOM hikes.
- Deemed Generation: If your factory shuts down for unexpected maintenance, grid shutdown, or strike, developers usually charge for "deemed generation." Negotiate a minimum allowance of 15–20 days per year exempt from deemed charges.
- Buyout & Termination Matrix: Ensure a clear, written buy-out schedule allowing the plant owner to purchase the solar system at fair market value in Year 5, Year 10, or Year 15.
4. Which Model Should Your Business Choose?
Choose CAPEX If: Your company is profitable with high taxable income (utilizing the 40% depreciation shield), has access to low-interest green loans (IREDA, SIDBI, SBI 4E at 7.5%–8.5%), and owns the physical premises.
Choose OPEX / RESCO If: Capital is strictly needed for core inventory and factory expansion, the roof is on a long-term lease (10+ years), or management wants zero operational headache regarding panel cleaning, inverter breakdowns, or degradation monitoring.