What is RESCO
RESCO, Renewable Energy Service Company, is a solar deployment model in which a third-party developer designs, finances, installs, owns and operates the solar PV system on the customer’s premises, and sells the generated electricity to the customer at a discounted PPA tariff. The customer commits zero upfront capex and pays only the monthly electricity bill at the RESCO tariff for the contract term, typically 15 to 25 years.
The model first scaled in the United States around 2010 as residential solar PPAs (SolarCity, Sunrun). In India, RESCO has scaled primarily in C&I rooftop solar from 2015 onward, with major players including Cleantech Solar, Amplus, Fourth Partner Energy, ReNew, Tata Power Solar, Azure Power and others.
For C&I customers, RESCO eliminates the capex barrier and outsources operational complexity. The developer captures the residual project value through PPA revenue minus expected lifecycle cost.
RESCO explained simply
A solar company says: I will put solar panels on your factory roof for free. You buy the electricity from me at a discount to what the DISCOM charges. I make money over time, you save money from day one.
The catch is a long-term contract (typically 15 to 25 years). You commit to buying the electricity, the developer commits to delivering it. Both sides win if the math works. This zero-upfront structure is broken down in more detail in Zero Cost Solar India, RESCO and OPEX Models Explained.
Why RESCO matters
Zero capex. Removes the upfront barrier to C&I solar adoption.
Outsourced O&M. Customer focuses on core business; developer carries the OPEX burden and manages the asset.
Day-one savings. PPA tariff is below retail from month one.
Bankability. Developers raise project finance against committed PPA cash flow.
Scale. India’s C&I rooftop sector grew from 1 GW in 2017 to over 10 GW by 2025 substantially through RESCO, a shift covered in the complete RESCO model guide for C&I buyers.
Lower risk for customer. Performance risk sits with developer.
How RESCO works
- Developer evaluates customer’s electricity bill, sanctioned load and roof area.
- Developer proposes a PPA tariff (typically 10 to 30 percent below retail), backed by a system layout produced with commercial solar design software.
- Customer signs 15 to 25 year PPA with the developer.
- Developer arranges project finance, installs and commissions the system.
- System generates electricity, customer consumes it directly through net metering.
- Monthly meter reading and PPA invoice from developer.
- At end of PPA term, system either transfers to customer (at nominal value) or is removed.
Technical deep dive
RESCO economics for the customer
| Element | Detail |
|---|---|
| Upfront capex | Zero |
| Monthly bill | PPA tariff × kWh generated |
| Retail tariff (for comparison) | ₹7 to ₹10/kWh typical C&I |
| RESCO tariff | ₹4.5 to ₹7/kWh typical |
| Annual savings | 25 to 35% of solar-offset bill |
| Total savings over 25 years | 200 to 500% of original capex equivalent |
Because there is no capex outlay, the payback period metric does not apply to RESCO customers; day-one savings against the RESCO tariff are the relevant measure instead.
RESCO economics for the developer
| Element | Detail |
|---|---|
| Project capex (₹/MW) | 3.5 to 4.5 crore |
| Annual revenue (₹/MW) | 80 to 110 lakh |
| O&M cost (₹/MW/year) | 7 to 12 lakh |
| Annual net cash flow | 70 to 100 lakh per MW |
| Project IRR | 12 to 16% pre-tax |
Contract structure
| Term | Typical value |
|---|---|
| Duration | 15 to 25 years |
| Tariff | Fixed, sometimes with annual escalation |
| Performance guarantee | Minimum CUF or PR |
| O&M responsibility | Developer |
| End-of-term ownership | Transfer to customer or removal |
| Termination | Cure period for default, buyout option |
Real-world applications
C&I rooftop solar installation across manufacturing, IT, retail and hospitality sectors.
Multi-site retail chains.
Industrial parks and SEZs.
Educational and healthcare institutions.
PSU and government buildings (RESCO-mode procurement).
Carports for shopping malls and tech parks.
Advantages
Zero capex for customer.
Immediate savings.
Outsourced O&M complexity.
Performance risk on developer.
Bankable scale model for C&I solar.
Limitations
Long-term contractual commitment.
Higher cumulative cost than CAPEX over 25 years.
Customer credit risk affects developer.
Roof access and ownership clauses are complex.
Tenancy changes require contract assignment.
Common problems
Customer default during contract. Developer has limited remedies, system removal is costly.
Building ownership change without contract assignment.
Performance shortfalls due to shading the developer did not foresee.
Net metering rule changes mid-contract affecting tariff economics.
DISCOM tariff revisions changing the comparative savings.
Site access for O&M.
Best practices
Evaluate developer track record and financial backing.
Negotiate PPA tariff floor and ceiling to handle volatility.
Document roof access and tenancy provisions.
Include performance guarantee with measurement mechanism.
Plan for change in DISCOM tariff during contract.
Maintain detailed monthly generation and billing records.
Comparison: RESCO vs CAPEX vs PM Surya Ghar
| Feature | RESCO | CAPEX | PM Surya Ghar |
|---|---|---|---|
| Upfront cost | Zero | Full capex | Net of subsidy |
| Ownership | Developer | Customer | Customer |
| O&M | Developer | Customer | Customer |
| Lifecycle savings | Lower | Highest | Highest with subsidy |
| Risk | Lowest | Highest | Medium |
| Best for | Large C&I, no capex | Capex-rich C&I and residential | Residential under subsidy |
Indian market context
Major Indian RESCO developers include Cleantech Solar, Amplus Energy, Fourth Partner Energy, ReNew Power, Tata Power Solar, Azure Power, Mahindra Susten and others.
Investment-grade C&I customers are the primary RESCO market. Smaller customers face limited developer interest due to credit risk.
PM Surya Ghar does not subsidise RESCO residential. Capex-based residential dominates the subsidised segment.
Recent SECI tenders include RESCO-style PPA structures for institutional and government rooftops.
The Cabinet Secretariat and various PSUs use RESCO for institutional rooftops as policy.
Standards and certifications
| Standard | Scope |
|---|---|
| MNRE RESCO guidelines | Indian framework |
| State SERC net metering regulations | Eligibility and tariff |
| Electricity Act 2003 | Statutory basis |
| ALMM | Module and cell requirements |
| BIS certification | Quality compliance |
Common mistakes
Choosing developer based on lowest PPA without checking financial strength.
Missing tenancy and roof access clauses.
Overlooking termination terms.
Not validating performance guarantee enforcement mechanism.
Ignoring DISCOM tariff trajectory in long-term modelling.
Skipping insurance and indemnity terms.
Key takeaways
RESCO is the zero-capex solar model where a third-party developer installs and operates the system on the customer’s premises, with the customer buying generated electricity at a discounted PPA tariff. India’s C&I rooftop solar market has scaled significantly through RESCO. Day-one savings, outsourced O&M and developer-borne performance risk drive customer adoption. Long contract terms, credit underwriting and contract clauses are the design choices that decide whether the structure delivers.
Choosing an inverter for a RESCO project
Qbits Energy makes solar inverters. It does not develop, finance or own RESCO projects. Developers and C&I buyers comparing inverters for a rooftop project can see the on grid inverter range or contact the team.
Further reading
For how RESCO plays out in real projects, these guides go deeper:
- Solar RESCO Model India: Guide for C&I Buyers
- Solar CAPEX vs OPEX: The C&I Buyer Decision Guide
- Zero Cost Solar India: RESCO & OPEX Models
- Solar CAPEX vs OPEX: Which Model Fits Your Business?
Sources
- MNRE Guidelines for Rooftop Solar Programme and RESCO Mode.
- State Electricity Regulatory Commission net metering regulations.
- Electricity Act 2003, Government of India.
- IEA Renewables 2024.
- BRIDGE TO INDIA reports on rooftop solar market.
- IRENA Country Profile for India, Renewable Energy Statistics 2024.
- SECI Tender Documents for institutional rooftop solar.
- Mercom India Solar Market reports.
- IEA PVPS Trends in Photovoltaic Applications 2024.
Frequently Asked Questions
What is RESCO in simple words?
What does RESCO stand for?
How is RESCO different from CAPEX model?
What is the typical RESCO PPA tariff?
How long is a RESCO PPA?
Who owns the rooftop system in RESCO?
Can residential customers use RESCO?
What if I move out of the building?
Who handles O&M in RESCO?
Can the developer remove the system?
Is RESCO eligible for PM Surya Ghar?
What is the typical RESCO PPA term?
Does RESCO require credit rating?
Is the savings guaranteed in RESCO?
What is the cost of a RESCO system to the customer?
From the Blog
CFO overseeing solar financing, procurement, and channel partner enablement at Qbits.