For Indian enterprises, electricity is no longer just an operational utility—it is a volatile financial liability. With commercial and industrial (C&I) grid tariffs escalating by 6% to 9% annually across major industrialized states like Maharashtra, Tamil Nadu, Gujarat, and Karnataka, energy costs are directly squeezing corporate operating margins.
As forward-thinking enterprises commit to Net-Zero targets and look for ways to optimize operational expenses (OPEX), transitioning to solar energy has shifted from a corporate social responsibility (CSR) initiative to a core treasury strategy.
Yet, the ultimate barrier to solar adoption is rarely technology; it is financial structuring. CFOs and business owners are repeatedly confronted with a vital strategic question: "How do we transition to commercial solar energy without disrupting our working capital or compromising our balance sheet liquidity?
At Rayzon Green, we believe that clean energy transition should be a source of financial strength, not a cash flow puzzle. The Indian market offers highly sophisticated, regulatory-backed financing models tailored to different corporate balance sheets.
This comprehensive guide breaks down the three primary commercial solar financing models in India: CAPEX, OPEX (RESCO), and Power Purchase Agreements (PPAs) (including On-Site and Off-Site Open Access). By the end of this deep dive, your finance team will possess a clear roadmap to selecting the optimal financial vehicle for your solar transition.
Each model offers a different balance of investment, ownership, savings, operational responsibility and financial risk. Choosing the right structure can determine how quickly a business begins saving, how much value it receives over the project lifecycle and how easily the project aligns with its financial strategy.
This guide explains CAPEX, OPEX and PPA solar models in the Indian commercial and industrial context so that businesses can make a more informed solar investment decision.
Before evaluating individual financing structures, it is essential to understand why solar the most lucrative hedge against inflation in India is today.
Average commercial grid tariffs in India hover between INR 7.50 and INR 11.50 per kWh. In contrast, the levelized cost of energy (LCOE) for a self-owned rooftop solar system over its 25-year lifetime is less than INR 2.50 per kWh. This massive arbitrage opportunity - exceeding 70% in high-tariff zones - is what makes solar financing models highly attractive to both businesses and institutional investors.
Additionally, under the Government of India’s push for decarbonization, policy frameworks like the Green Energy Open Access Rules have democratized access to solar power, allowing even land-constrained industrial units to procure green energy from off-site solar parks.
The three commonly discussed commercial solar financing structures are:
In practice, OPEX is the broader financing and ownership structure, while a Power Purchase Agreement, or PPA, is usually the contract through which the customer pays for the electricity generated under that structure.
Indian government solar documentation formally recognises CAPEX and RESCO/PPA as established rooftop solar business models. Under CAPEX, the rooftop owner makes the investment. Under RESCO/PPA, the project developer invests in the system and supplies solar electricity to the consumer.
|
Factor |
CAPEX Solar |
OPEX Solar |
PPA-Based Solar |
|
Initial investment |
Paid by the business |
Paid by the solar developer |
Generally paid by the solar developer |
|
Plant ownership |
Business owns the plant |
Developer owns the plant during the contract |
Depends on the PPA structure; commonly developer-owned |
|
Payment method |
Upfront investment or financed purchase |
Payment for solar energy or agreed service |
Per-unit electricity tariff under contract |
|
Operations and maintenance |
Business or appointed O&M partner |
Usually handled by developer |
Usually handled by developer |
|
Savings potential |
Typically stronger over the full lifecycle |
Immediate savings without high upfront capital |
Savings depend on PPA tariff and contract terms |
|
Contract commitment |
Lower after purchase |
Usually long term |
Long-term contractual commitment |
|
Performance responsibility |
Primarily with plant owner and EPC/O&M partner |
Primarily with developer, subject to contract |
Defined through PPA obligations |
|
Best suited for |
Businesses with available capital and a long-term ownership strategy |
Businesses protecting working capital |
Businesses seeking predictable solar tariffs |
The right model should not be selected only on the basis of the lowest quoted tariff. Businesses should also evaluate plant quality, expected generation, contract tenure, escalation clauses, maintenance standards and long-term operational risk.
CAPEX stands for capital expenditure.
Under a CAPEX solar model, the commercial or industrial consumer purchases the solar power plant using its own capital, a bank loan or another financing facility. The customer becomes the owner of the system and receives the electricity generated by it.
The Government of NCT of Delhi’s renewable-energy guidance similarly describes CAPEX as a structure in which a consumer with access to a suitable roof and sufficient capital directly purchases the rooftop solar system from a solar vendor.
The owner is responsible for the plant, although engineering, procurement, construction, monitoring and maintenance can be assigned to an experienced solar EPC and O&M company.
The solar plant becomes an asset of the business. The owner retains control over equipment selection, engineering standards, monitoring systems and maintenance strategy.
After the initial investment is recovered, the electricity produced by the system can continue reducing grid-power consumption for many years, subject to plant performance and maintenance.
The business can select the modules, inverters, mounting structures, safety systems and technical specifications that meet its operational requirements.
The owner can choose a qualified O&M provider, establish performance benchmarks and upgrade monitoring or equipment when necessary.
A business-owned solar asset may have depreciation, financing and accounting implications. The actual treatment depends on the company, project structure and prevailing tax rules. Businesses should obtain advice from qualified financial and tax professionals before including such benefits in an investment calculation.
A commercial solar project may require a significant upfront investment. This capital could otherwise be used for machinery, expansion, inventory or working capital.
The plant owner carries the risks associated with equipment performance, maintenance quality and component replacement, except where these are covered by warranties or service contracts.
Poor cleaning, delayed fault detection, inverter downtime and inadequate preventive maintenance can reduce the plant’s output and weaken projected returns.
The owner must carefully evaluate EPC quality rather than selecting a project only on the basis of its initial price.
CAPEX may be suitable for:
Suppose a manufacturing facility installs a rooftop solar plant through the CAPEX model.
The company pays for the installation and owns the plant. Solar electricity is consumed within the facility, reducing the amount of power purchased from the grid. Over time, accumulated electricity-cost savings may recover the original investment.
After the payback period, continued generation can contribute to further savings, although operating expenses, equipment degradation, maintenance and replacement requirements must still be considered.
OPEX stands for operational expenditure.
In an OPEX solar arrangement, commonly called the RESCO model, a solar developer finances, installs, owns, operates and maintains the solar plant. The commercial consumer provides the installation space and purchases the electricity generated by the system.
Official MNRE rooftop solar documentation describes the RESCO structure as one in which the developer finances, installs, operates and maintains the rooftop solar plant.
A government renewable-energy agency also explains that, under RESCO, the consumer generally does not make the plant investment; the RESCO provider handles installation, repair and maintenance while the consumer provides suitable rooftop space and purchases the electricity.
The consumer can adopt solar without allocating a large amount of capital to plant ownership.
Funds remain available for core business activities, production equipment, expansion and operations.
The developer is generally responsible for operations, monitoring, preventive maintenance and fault resolution, as defined in the agreement.
When the agreed solar tariff is lower than the applicable effective grid-power cost, the consumer can begin saving without waiting to recover a large initial investment.
System design, equipment procurement and lifecycle maintenance are largely managed by the project developer.
OPEX contracts may continue for several years. The consumer must evaluate whether it expects to remain at the location and maintain sufficient electricity demand throughout the term.
Because the developer invests capital based partly on future electricity payments, the consumer’s creditworthiness and financial stability may influence project approval and tariff terms.
The developer usually selects the equipment, subject to contractual specifications. The consumer should therefore insist on clearly defined quality, safety and performance standards.
Business relocation, facility sale, roof renovation or changes in electricity demand can create contractual complications.
Plant performance, service quality and responsiveness depend on the technical and financial strength of the developer.
OPEX may be suitable for:
A solar Power Purchase Agreement is a contract under which a consumer agrees to purchase electricity from a solar project developer at a defined tariff and under specified commercial terms.
A PPA normally addresses matters such as:
MNRE’s rooftop solar knowledge resources include a model PPA intended for execution between consumers and RESCO developers, demonstrating the importance of a clearly documented contractual framework.
OPEX and PPA are closely connected, but they are not exactly the same.
OPEX describes how the project is financed, owned and operated.
PPA describes how the electricity is sold and purchased.
In a typical on-site commercial solar arrangement:
Therefore, many projects are described as OPEX-PPA or RESCO-PPA projects.
A PPA can also be used for an off-site solar project, where electricity is generated at another location and supplied or accounted for through the grid under the applicable open-access framework.
The solar plant is installed on the customer’s rooftop or premises.
The customer uses the electricity generated at the facility and pays the developer according to the agreed tariff and metered generation.
The solar project is located away from the consumer’s facility. Electricity is supplied through the grid under the relevant open-access or captive framework.
The financial viability of off-site procurement depends on several variables, including state regulations, transmission or wheeling arrangements, banking rules, applicable surcharges and the consumer’s load profile.
Because these provisions may vary by state and change over time, businesses should conduct a current regulatory and landed-tariff assessment before signing an off-site PPA.
A predefined tariff can give businesses greater visibility into future energy costs.
The consumer purchases energy instead of purchasing the solar asset.
Because revenue generally depends on electricity generation, the developer has an incentive to maintain plant availability and performance.
A PPA can support renewable-energy procurement without requiring the consumer to develop in-house solar operating capabilities.
The consumer may begin saving when the effective solar tariff is below its comparable grid-power cost, after considering all applicable charges.
A low tariff alone does not make a PPA attractive. Businesses should examine the full agreement.
Determine whether the tariff remains fixed or increases annually.
Some agreements may require the consumer to purchase or pay for a defined amount of electricity.
The contract should explain what happens when the solar plant is available but the customer cannot consume or accept the electricity.
Responsibilities during roof repairs, factory shutdowns or structural modifications should be clearly documented.
The agreement should specify how regulatory changes, taxes, duties or new charges will be addressed.
Termination payments and asset-removal obligations should be understood before signing.
The consumer should confirm whether the plant will be transferred, extended, purchased or removed when the agreement expires.
CAPEX often has the potential to deliver greater cumulative savings over the complete project life because the business owns the plant and does not continue paying a developer’s per-unit tariff throughout the contract period.
However, CAPEX also requires the business to invest capital and assume ownership-related risks.
OPEX may provide lower absolute lifetime savings than direct ownership, but it allows the business to adopt solar with limited upfront expenditure and transfer many operational responsibilities to the developer.
The better model therefore depends on the organisation’s priorities:
Could the business fund the solar plant without affecting core operations or expansion plans?
If yes, CAPEX may deserve consideration. If capital is constrained or better used elsewhere, OPEX may be more appropriate.
A business investing through CAPEX should ideally have long-term control over the site.
For OPEX and PPA projects, the site must generally remain available for the contractual term.
Businesses operating from leased premises should review roof rights, landlord approvals, structural responsibilities and agreement duration.
Solar projects perform best financially when generation can be effectively consumed or settled under the applicable framework.
The assessment should examine:
A commercial evaluation should account for:
The financing structure cannot compensate for weak engineering.
Businesses should assess:
Commercial solar rules are not identical across India.
Net metering, net billing, open access, banking, wheeling charges and other commercial provisions may differ across states and consumer categories. Regulations can also be amended.
Every project should therefore undergo a location-specific regulatory review before its financial model is finalised.
A low initial price may involve compromises in equipment, structure, cabling, safety systems or maintenance support.
The comparison should consider the complete effective cost of conventional electricity and every applicable solar-related charge.
A plant sized only on current electricity bills may become unsuitable if production, operating hours or facility use changes.
A long-term energy contract should be reviewed by technical, legal and financial teams.
Solar plants are low-maintenance, not maintenance-free. Cleaning, inspections, monitoring and timely corrective action remain essential.
A company with multiple facilities may use CAPEX at one location and OPEX or off-site procurement at another.
Partnering with Rayzon Green: Beyond Modules to Complete Energy Solvency
Transitioning your enterprise to solar is more than an engineering project; it is a long-term capital allocation strategy.
At Rayzon Green,we do not believe in one-size-fits-all templates. We are not just manufacturers of world-class, high-efficiency solar modules; we are strategic energy partners.
Our in-house project finance and engineering divisions work closely with your treasury team to:
By pairing Rayzon Green's cutting-edge PV technology (engineered for maximum generation per square meter under diverse Indian climatic conditions) with smart, tailored financial structuring, we ensure your solar transition delivers the highest possible internal rate of return IRR and lowest levelized cost of energy LCOE.
CAPEX, OPEX and PPA models all provide viable pathways for commercial solar adoption in India, but they serve different business needs.
CAPEX offers ownership, control and strong long-term value potential.
OPEX enables solar adoption with limited upfront investment and developer-managed operations.
A PPA provides a contractual framework for purchasing solar electricity at an agreed tariff.
The best option is not necessarily the model with the lowest initial project cost or the lowest advertised tariff. It is the model that delivers the right combination of:
Before making a decision, businesses should complete a detailed technical, financial, legal and regulatory assessment.
With the right financing structure and a capable solar EPC partner, solar becomes more than an electricity-saving measure. It becomes a long-term business asset that supports cost control, energy planning and sustainable growth.
Planning a commercial or industrial solar project?
Connect with Rayzon Green for a detailed site assessment, financial model comparison and end-to-end solar EPC solution designed around your business requirements.
Under CAPEX, the business pays for and owns the solar plant. Under OPEX, a third-party developer generally invests in, owns, operates and maintains the plant while the customer purchases the solar electricity generated.
Not exactly. OPEX is the financing and ownership model. A PPA is the contract that defines how the customer purchases electricity from the developer. Many OPEX projects operate through a PPA.
An OPEX or RESCO-PPA model generally requires little or no upfront plant investment from the consumer, subject to the commercial agreement and any project-specific charges.
CAPEX can suit businesses seeking asset ownership and higher long-term savings potential. OPEX can suit businesses that want to preserve capital and transfer plant operations to a developer.
In a typical OPEX-PPA arrangement, the solar developer owns the plant during the PPA term. Ownership at the end of the agreement depends on the transfer, purchase, extension or removal provisions in the contract.
The term varies by project and developer. Businesses should evaluate the complete tenure, tariff, escalation, termination and end-of-term conditions rather than judging the agreement only by its starting tariff.
Yes, subject to landlord permission, structural suitability, roof-access rights, lease duration and contractual arrangements. The solar agreement should not extend beyond the period for which the consumer can reliably control the site unless suitable protections are included.
Usually, yes. The developer generally operates and maintains the plant, but exact service levels, response times and performance obligations must be specified in the agreement.
Yes. A company with several facilities may choose CAPEX for owned locations and OPEX or off-site PPAs for sites where capital, roof space or tenure is limited.
