CAPEX vs OPEX vs Open Access: How Solar EPC Contractors Guide Indian Industries

Rising power tariffs, ESG pressure, and 24×7 operations are pushing Indian industries to look at solar in a serious, structured way. The real confusion usually is not “solar yes or no”, but which model makes business sense: CAPEX, OPEX, or open access, and how an EPC contractor fits into each.

This guide breaks down these models in simple language and explains how a solar EPC contractor helps commercial and industrial (C&I) buyers choose and implement the right structure in India.

Why the model matters as much as the plant

For most factories and commercial units, solar is a 20–25 year decision, not just a one-time purchase. The way you structure your project affects cash flow, balance sheet, tariff, risk, and control over the asset.

A good solar EPC contractor does more than install panels. The EPC team studies your load pattern, tariff, roof or land availability, and risk appetite, then maps how CAPEX, OPEX, and open access would play out over the project life using your actual data, not generic assumptions. That shift from selling kilowatts to solving a business problem is what most C&I buyers actually need.

CAPEX solar: own the asset, own the savings

What is CAPEX solar?

In a CAPEX model, the C&I consumer pays upfront for the solar plant and owns the asset from day one. The EPC contractor is hired on a turnkey basis to engineer, procure, construct, and commission the plant, usually under performance and workmanship guarantees.

Where CAPEX works well

CAPEX tends to suit businesses that:

Have internal funds or access to debt at a reasonable cost.
Want the lowest levelised cost of energy and maximum savings over 20–25 years.
Prefer to claim depreciation and other tax benefits on their own books.

The trade-off is the high initial investment and the responsibility for long-term O&M and performance.

EPC contractor’s role in CAPEX

Under CAPEX, the EPC contractor has a direct impact on long-term performance and reliability:
Conducting detailed engineering, structural checks, and yield simulations before capex is finalised.
Selecting modules, inverters, structures, and cabling suitable for Indian heat, dust, wind load, and monsoon conditions.
Managing site execution, safety, quality control, and commissioning to meet grid and regulatory standards.

Many C&I buyers also extend the relationship through separate O&M contracts, so accountability for generation stays with one experienced team.

OPEX / RESCO solar: go solar with minimal capex

What is OPEX / RESCO?

In an OPEX or RESCO model, a third-party developer invests in and owns the solar plant, and the consumer only pays for the energy generated at an agreed tariff under a long-term power purchase agreement (PPA). The plant can be on the consumer’s premises or off-site, depending on the arrangement and local regulations.

Where OPEX works well

OPEX appeals to businesses that:

Want to avoid heavy upfront capex and preserve cash for core operations.
Prefer a predictable per-unit tariff and minimal operational involvement.
Are comfortable with a long-term contract and sharing upside with a developer.

The trade-offs include tariff escalation clauses, lock-in periods, and lower direct control over technology choices and upgrades.

EPC contractor’s role in OPEX deals

Even though the asset is owned by the developer, an EPC contractor often executes the project:

Delivering detailed design, procurement, and construction as per the developer’s and off taker’s technical and safety requirements.
Ensuring plant availability and performance so that PPA obligations can be met reliably over the contract period.
Coordinating with the consumer on shutdown windows, integration with existing electrical systems, and on-site safety practices.

For the end customer, it still matters who the EPC is, because the quality of engineering and construction decides how stable the PPA supply will be for 15–25 years.

Open access solar: power beyond your factory roof

What is open access solar in India?

Open access lets eligible consumers purchase power from off site solar plants using the existing grid. This can be done under captive, group captive, or third party sale structures. With the Green Energy Open Access Rules, many states now allow consumers with a contracted load of 100 kW to participate, which has opened the market for a wide range of commercial and industrial users.

In a typical arrangement, developers set up solar plants on suitable land, connect them to the grid, and supply electricity to one or multiple C&I offtakers under state and central open access regulations.

Where open access works well

Open access often fits industries that:

Have high and stable load across the year, sometimes spread across several facilities.
Have limited roof space or structurally unsuitable roofs but want significant solar adoption.
Are prepared to navigate regulations, open access charges, banking rules, and periodic policy changes.

The complexity usually comes from eligibility conditions, wheeling and banking rules, cross subsidy surcharge, additional surcharge, and state level deviations from central guidelines.

EPC contractor’s role in open access projects

In open access projects, a specialised solar EPC partner is critical for technical robustness and bankability. Their responsibilities include:

Designing plant layout, structures, and evacuation systems that meet grid codes, utility rules, and long term performance expectations.
Coordinating technical studies, metering, and protection schemes with DISCOMs, transmission utilities, and load dispatch centres.
Executing the plant and evacuation infrastructure to ensure resilience to local environmental and grid conditions.

For C&I consumers, the EPC’s engineering quality directly impacts export capability, billing accuracy, and long term financial savings.

Which model suits which industry type?

Start with your load and tariff profile. A practical way to identify the right model is to examine:

Day versus night consumption for every facility.
Seasonal fluctuations in load and solar generation.
Current landed tariff and likely future escalations.

For example, a single unit with a strong daytime load and adequate roof space may find CAPEX rooftop ideal. A multi location organisation with limited roof availability may benefit from combining rooftop and open access models.

Consider balance sheet strength and risk appetite

CAPEX fits companies ready to invest now for long term savings, greater control, and tax advantages.
OPEX suits businesses that want to preserve capital and avoid adding solar assets to the balance sheet.
Open access works for large, stable loads where management is prepared to handle regulatory complexity for deeper savings.

A skilled EPC partner helps compare LCOE and IRR across models using real tariff and consumption data rather than generic assumptions.

How EPC contractors de risk your solar decision

Turning complexity into a structured feasibility. A strong EPC does not push a single model. Instead, they begin with a pre feasibility study that includes:

Reviewing past bills, demand charges, and load curves.
Assessing rooftop and land availability, structural capacity, and electrical layout.
Mapping CAPEX, OPEX, and open access scenarios with indicative tariffs, expected savings, and risks over 15 to 20 years.

This gives decision makers a clear side by side comparison of options for each site or cluster of sites.

Aligning contracts, execution, and compliance

The EPC stands at the intersection of engineering, approvals, and contracting:

Aligning design and BOQ with PPA clauses, EPC contracts, and SLAs to ensure clarity on responsibilities.
Preparing technical documents and drawings required by DISCOMs, CEIG, and other authorities.
Ensuring the commissioned plant meets capacity, safety, and grid readiness standards so financiers and auditors are confident.

With long term O&M and monitoring support, the EPC ensures the system maintains performance and remains compliant as tariffs, loads, and policies evolve.

How Infisol Energy can support your solar strategy

Infisol Energy is a focused solar EPC contractor working with commercial and industrial consumers on rooftop, ground-mounted, and open access projects in India. The team has practical experience across CAPEX, OPEX linked EPC, and open access executions, including industrial rooftops, hazardous sites, and multi MW projects.

We help C&I buyers analyse their load and tariff data, compare CAPEX, OPEX, and open access options for each facility or group of facilities, and then execute the chosen model from design and approvals to commissioning and O&M. This combination of technical depth and project structuring experience is designed to make solar a reliable, long term part of your energy mix.

When should you speak to an EPC partner like Infisol?

Many C&I buyers start by collecting price quotes or PPA offers and only later realise they needed a neutral technical financial view at the beginning. Bringing an experienced EPC contractor into the discussion early helps:

Shortlist the right model for each site or region instead of forcing one structure everywhere.
Avoid undersized or oversized systems that restrict future expansion or open access plans.
Plan realistic execution timelines around plant shutdowns, approvals, and regulatory windows.

If your team is evaluating solar for one or more facilities in India and wants a clear CAPEX, OPEX, and Open access comparison based on real consumption data, we can first study your past bills and load profile and build a simple, side by side view for each option. Based on that, we suggest the mix of rooftop, ground mounted, and open access capacity that fits your operations, risk appetite, and expansion plans.

Once you are comfortable with the direction, our EPC team takes the project forward from detailed design and approvals to on site execution and long term O&M support.

If you would like our team to run this analysis for your plant, call us on +91 80808 75082 or contact us with your basic load details and recent electricity bills. We will get back to you with a structured solar feasibility and next steps that match your business priorities.