For Chennai businesses, electricity is one of the few costs you can lock down for 25 years. Commercial and industrial (C&I) tariffs in Tamil Nadu run from about ₹7.50 to over ₹10 a unit, while a rooftop plant generates power for a fraction of that. A well-designed commercial or industrial solar EPC project in Chennai typically pays for itself in about 3–4 years, with tax benefits that shorten it further.
- Cost: roughly ₹30,000–50,000 per kW; a 100 kW plant costs about ₹30–50 lakh, with lower per-kW cost at larger sizes.
- Generation: about 1,400–1,550 units per kW per year in Chennai; 100 kW makes about 1.45 lakh units a year.
- Savings: about ₹11–15 lakh a year for 100 kW, depending on your tariff category.
- Payback: about 2.5–4 years, plus 40% accelerated depreciation in year one for eligible businesses.
- Subsidy: the PM Surya Ghar subsidy is for homes and housing societies, not businesses. The benefit for businesses comes through tax depreciation and lower bills.
Who C&I rooftop solar suits in Chennai
Solar gives the best return where large daytime loads meet large, shade-free roofs:
- Factories and MSMEs in Ambattur, Guindy, Sriperumbudur, Oragadam, Maraimalai Nagar and Gummidipoondi, with day-shift loads and large sheet roofs
- Warehouses and logistics parks, with huge roofs and modest loads (ideal for maximum capacity)
- Hospitals and clinics, with round-the-clock loads, ACs and equipment
- Schools, colleges and institutions, with daytime use and large terraces
- Offices, IT units and showrooms, with daytime air-conditioning. See our guide to commercial solar for offices in Chennai
- Hotels, malls and cold storage, with high, steady consumption
Commercial & industrial solar cost in Chennai by plant size
| Plant size | Indicative cost | Roof area needed (approx.) | Units per year (approx.) |
|---|---|---|---|
| 50 kW | ₹15–25 lakh | 4,000–5,000 sq ft | 70,000–77,500 |
| 100 kW | ₹30–50 lakh | 8,000–10,000 sq ft | 1.4–1.55 lakh |
| 250 kW | ₹75 lakh–1.25 crore | 20,000–25,000 sq ft | 3.5–3.9 lakh |
| 500 kW | ₹1.5–2.5 crore | 40,000–50,000 sq ft | 7–7.75 lakh |
| 1 MW | ₹3–5 crore | 80,000–1,00,000 sq ft | 14–15.5 lakh |
The per-kW cost falls as size grows. The final figure depends on roof type (metal sheet vs RCC), structure height, panel and inverter brands, cable runs to the main panel, and whether HT-side equipment is needed. Always ask for an itemised bill of materials.
Tamil Nadu C&I tariffs: what solar replaces
Solar replaces the energy charge on your bill. Under the TNERC tariff order effective 1 July 2025, energy charges for common business categories are:
| Category | Typical users | Energy charge (₹/unit) |
|---|---|---|
| HT I | Industries, factories, IT services | 7.50 |
| HT II (A/B) | Hospitals, educational institutions | 7.75–8.25 |
| HT III | Commercial | 9.40 |
| LT III-B | LT industries | 8.25 |
| LT V | LT commercial (above 100 units) | 10.45 |
For HT consumers, a 25% surcharge applies to energy used during peak hours (6–10 am and 6–10 pm). Morning solar generation offsets some of these expensive peak units.
One thing solar does not cut: the HT demand charge (₹608 per kVA per month), which is based on your maximum demand. A good EPC design accounts for this, so your savings estimate is realistic. Tariffs are revised periodically, and an inflation-linked adjustment was due from July 2026, so confirm current rates on your bill.
ROI and payback: worked examples for a 100 kW plant
Assumptions: 100 kW producing about 1.45 lakh units a year, all consumed on site during working hours, and a plant cost of ₹40 lakh.
| Your tariff category | Energy charge | Approx. savings per year | Simple payback |
|---|---|---|---|
| HT I industry | ₹7.50 | ≈ ₹10.9 lakh | ≈ 3.7 years |
| LT III-B industry | ₹8.25 | ≈ ₹12.0 lakh | ≈ 3.3 years |
| HT III commercial | ₹9.40 | ≈ ₹13.6 lakh | ≈ 2.9 years |
| LT V commercial | ₹10.45 | ≈ ₹15.2 lakh | ≈ 2.6 years |
Accelerated depreciation: businesses that own the plant can generally claim 40% depreciation on solar assets in the first year under Section 32 of the Income Tax Act. On a ₹40 lakh plant, that is a ₹16 lakh deduction, worth roughly ₹4 lakh in tax at a 25% corporate rate. Confirm eligibility with your chartered accountant.
Illustrative only. Actual savings depend on your load profile, how much solar is consumed on site, export settlement, applicable grid charges, O&M costs (typically around 1% of plant cost a year) and panel degradation.
How to finance it: CAPEX, loan or RESCO?
| Model | How it works | Best for | Trade-off |
|---|---|---|---|
| CAPEX | You pay for and own the plant | Profitable businesses with cash or credit | Highest lifetime savings, plus the depreciation benefit |
| Solar or term loan | A bank or NBFC funds most of the cost; you own the plant | Businesses preserving working capital; MSMEs may access priority-sector lending | Interest cost, but you keep the depreciation benefit |
| RESCO / OPEX (PPA) | A developer installs and owns the plant; you buy its power per unit at a rate below your grid tariff | Businesses wanting zero upfront cost | Lower savings than ownership; long contract (often 15–25 years); no depreciation for you |
| Group captive / open access | Buy solar from an off-site plant through the grid | Large HT consumers with limited roof space | Grid charges apply; more regulatory paperwork |
For home systems, see our separate guide to the solar loan in Chennai.
Metering and approvals in Tamil Nadu
- Capacity: rooftop capacity is generally limited by your sanctioned load or contract demand and your available roof area.
- Metering: LT commercial and industrial consumers can use net metering, where generation offsets consumption and surplus is settled as per TNERC rules. HT consumers follow separate metering and settlement arrangements set by TNERC.
- Approvals: the TNPDCL (formerly TANGEDCO) application and technical feasibility, Electrical Inspectorate safety approval where required, and meter installation and commissioning.
- Charges: TNERC regulations can include grid-related charges for some categories, and these change. Your EPC partner should factor in the current rules at the design stage. See our guide to TANGEDCO solar rules and regulations.
The C&I solar EPC process, step by step
Energy audit and bill analysis
Review 12 months of bills, tariff category, contract demand and the daily load profile to size the plant for maximum on-site use.
Site survey and structural check
Measure usable roof, check shading, and assess roof strength, especially purlins on metal-sheet roofs and waterproofing on RCC roofs.
Design and generation simulation
Panel layout, string design, inverter selection and a simulated yearly generation estimate for your exact site.
Proposal and financial model
An itemised bill of materials, project cost, savings, payback, depreciation benefit and financing options.
Approvals
TNPDCL application and feasibility, plus Electrical Inspectorate approval where applicable.
Procurement
ALMM-listed panels, inverters, structures, cables and protection equipment as per the approved design.
Installation
Structure, panels, cabling and inverters installed with safety measures for working at height, without disrupting operations.
Testing, inspection and commissioning
Electrical tests, inspection, meter installation and synchronisation with the grid.
O&M and monitoring
Remote monitoring, scheduled cleaning, preventive maintenance and performance reports.
A 100 kW project typically takes several weeks of execution after approvals, depending on the site and on how quickly approvals come through.
Roof types and design choices
| Roof or site | Typical solution |
|---|---|
| Metal sheet (factories, warehouses) | Rail or clamp mounting fixed to the sheet profile, walkways and safety lifelines; check purlin strength and sheet life first. |
| RCC terrace (offices, hospitals, schools) | Tilted or elevated structures; protect the waterproofing; keep access for maintenance. |
| Parking areas | Solar carports, which add shade and generate power. |
| Open land on site | Ground-mounted structures for larger capacities. |
In Chennai, every design should be cyclone-rated and use hot-dip galvanised steel, with corrosion protection for sites near the coast.
How to choose a C&I solar EPC partner
- C&I track record: completed plants of a similar size and roof type, with references you can call
- In-house design: a site-specific generation simulation, not a generic estimate
- Transparent bill of materials: panel, inverter and structure brands named in the contract
- Performance commitment: a generation or performance-ratio guarantee in writing
- O&M terms: response times, cleaning schedule and monitoring access
- Safety and insurance: working-at-height safety practices and project insurance
- Approvals experience: familiarity with TNPDCL and Electrical Inspectorate processes
Compare options in our list of the top solar EPC companies in Chennai, or see Arka's solar EPC services in Chennai.
Frequently asked questions
How much does a 100 kW commercial solar plant cost in Chennai?
Roughly ₹30–50 lakh in 2026, depending on roof type, structure, equipment brands and electrical work. Larger plants cost less per kW.
What is the payback period for industrial solar in Chennai?
Typically about 2.5–4 years under Tamil Nadu's 2025-26 C&I tariffs, when most of the solar power is used on site. Accelerated depreciation can shorten it further for businesses that own the plant.
Is there a government subsidy for commercial solar in Tamil Nadu?
The PM Surya Ghar subsidy is for residential consumers and housing societies, not businesses. Businesses benefit mainly through lower bills and 40% accelerated depreciation on solar assets.
Does solar reduce the HT demand charge?
Not significantly. Solar mainly reduces the energy charge. The demand charge depends on your maximum demand, which usually still occurs when solar output is low or loads peak.
What is the RESCO model?
A developer installs and owns the plant on your roof at no upfront cost, and you buy its power per unit at a rate below your grid tariff, usually under a 15–25 year agreement.
How many units does a 100 kW solar plant generate in Chennai?
About 1.4–1.55 lakh units a year, or roughly 380–420 units a day on average, depending on design, orientation and shading.
Can solar be installed on a metal-sheet factory roof?
Yes. Panels are mounted with rails or clamps fixed to the sheet profile. The roof's purlin strength and remaining sheet life should be checked first, and walkways and lifelines added for safe maintenance.
Get a free energy audit for your business
Arka Solar Energy, a solar company in Chennai, designs and installs on-grid, hybrid and high-capacity plants from 10 kW to multi-MW. Share 12 months of electricity bills and we will send a site-specific design, generation estimate and ROI model.
Costs, generation and savings are indicative. Tariffs are from the TNERC order effective 1 July 2025 and are subject to revision. Tax benefits depend on your business; consult your chartered accountant. Metering rules and charges are set by TNERC and TNPDCL and should be confirmed for your connection at the design stage.