A 100 kW plant is the most common size for factories, warehouses, hospitals, colleges and commercial buildings in Chennai. It is large enough to cut a business electricity bill by ₹10–15 lakh a year, yet small enough to fit on a typical factory roof. Below is a realistic 2026 price range, a component-by-component cost breakdown and the savings you can expect.
100 kW solar plant price in Chennai (2026)
| Specification level | Typical price | Price per watt | What you get |
|---|---|---|---|
| Budget | ₹30–34 lakh | ₹30–34 | Standard modules, basic structure, entry-level inverter brand |
| Standard (most common) | ₹35–40 lakh | ₹35–40 | Tier-1 mono PERC or TOPCon modules, reputed string inverters, hot-dip galvanised structure |
| Premium | ₹42–50 lakh | ₹42–50 | High-efficiency bifacial TOPCon, elevated structure, premium inverters, advanced monitoring |
Prices include GST and a complete EPC scope: design, supply, installation, approvals and commissioning. Since 22 September 2025, the effective GST on a solar EPC contract is about 8.9% (5% on the 70% goods portion and 18% on the 30% services portion), down from about 13.8%.
100 kW solar plant cost breakdown
Here is how the cost of a typical ₹38 lakh, 100 kW plant splits by component. Shares are approximate and vary by design.
| Component | Share of cost | Approx. amount |
|---|---|---|
| Solar panels (about 175–185 modules of 540–580 W) | 42–48% | ₹16–18 lakh |
| Inverters (for example, 2 × 50 kW string inverters) | 8–10% | ₹3–4 lakh |
| Mounting structure | 12–16% | ₹4.5–6 lakh |
| Electrical balance of system: DC and AC cables, ACDB/DCDB, earthing, lightning arrester | 10–13% | ₹4–5 lakh |
| Installation, civil work, testing and commissioning | 12–15% | ₹4.5–5.5 lakh |
| Design, approvals, metering liaison and monitoring | 3–5% | ₹1–2 lakh |
What makes a 100 kW plant cost more or less?
- Roof type: metal-sheet roofs use simple clamps and cost less to mount. RCC roofs with elevated structures need more steel. Asbestos-cement roofs may need an independent structure or a new roof first.
- Panel technology: bifacial TOPCon panels cost more per watt but generate more per sq ft, which matters when roof space is tight.
- Structure height and wind design: Chennai is a high-wind, cyclone-prone zone. A properly designed, hot-dip galvanised structure costs more but protects the investment. See solar in Chennai's monsoon and cyclones.
- Inverter brand: premium inverters with longer warranties and better monitoring add to the cost.
- Distance to the main panel: long cable runs from the roof to the LT panel add cost, especially on large or multi-building sites.
- Electrical upgrades: older factories may need panel, earthing or protection upgrades.
- Scope of O&M: a quote that includes multi-year maintenance and remote monitoring costs more up front but often less overall.
How many units does a 100 kW plant generate in Chennai?
| Period | Approximate generation |
|---|---|
| Per day (annual average) | ~400 units (higher in March–May, lower during the northeast monsoon) |
| Per month | ~12,000 units |
| Per year | ~1,40,000–1,55,000 units |
| Over 25 years (allowing for panel degradation) | ~33–35 lakh units |
Roof space: about 8,000–10,000 sq ft of shade-free roof on metal sheets, or 10,000–12,000 sq ft on an RCC roof with elevated structures. If your roof is smaller, a 50–75 kW plant may fit better, or bifacial high-efficiency panels can raise output per sq ft.
100 kW solar savings and payback by tariff
Your savings depend on your tariff category. Based on about 1,45,000 units a year used on site and a ₹38 lakh plant:
| Tariff category | Energy charge | Annual saving | Simple payback |
|---|---|---|---|
| HT I industrial | ₹7.50 / unit | ~₹10.9 lakh | ~3.5 years |
| HT II commercial / institutions | ₹7.75–8.25 / unit | ~₹11.2–12 lakh | ~3.2–3.4 years |
| LT IIIB industrial | ₹8.25 / unit | ~₹12 lakh | ~3.2 years |
| HT III commercial | ₹9.40 / unit | ~₹13.6 lakh | ~2.8 years |
| LT V commercial | ₹10.45 / unit | ~₹15.2 lakh | ~2.5 years |
These are year-one figures before panel degradation, tariff revisions and any applicable network charges. Solar reduces energy charges only; HT demand charges stay the same. HT consumers also benefit because solar offsets units in the morning peak (6–10 am), which carry a 25% surcharge. Over 25 years, a 100 kW plant at ₹8.25 a unit saves roughly ₹2.7–2.9 crore, even if tariffs never rise.
Solar plant cost in Chennai: 50 kW to 1 MW
| Plant size | Approximate cost | Units per year | Annual saving at ₹7.50–8.25 | Roof needed |
|---|---|---|---|---|
| 50 kW | ₹15–25 lakh | ~72,500 | ₹5.4–6 lakh | 4,000–6,000 sq ft |
| 100 kW | ₹30–50 lakh | ~1,45,000 | ₹10.9–12 lakh | 8,000–12,000 sq ft |
| 250 kW | ₹75 lakh–1.25 crore | ~3,62,500 | ₹27–30 lakh | 20,000–30,000 sq ft |
| 500 kW | ₹1.5–2.5 crore | ~7,25,000 | ₹54–60 lakh | 40,000–60,000 sq ft |
| 1 MW | ₹3–5 crore | ~14,50,000 | ₹1.09–1.2 crore | 80,000–1,20,000 sq ft |
Cost per kW falls as plants get larger, because design, approvals and installation overheads are spread over more capacity. For the full process, see commercial & industrial solar in Chennai: cost, ROI and process.
Tax benefits and funding options
- Accelerated depreciation: businesses that own their plant can claim 40% depreciation in the first year (20% if the plant is used for less than 180 days in that financial year). On a ₹38 lakh plant, that is about ₹15 lakh of depreciation, worth roughly ₹3.8 lakh in tax at a 25% corporate rate.
- Loan-funded purchase: a ₹40 lakh loan over 5 years at about 10% interest works out to roughly ₹85,000 a month, against about ₹1 lakh a month in savings for an LT industrial unit. See solar loans in Chennai.
- Zero investment (RESCO / OPEX): a developer owns the plant and you pay a lower per-unit rate. 100 kW is around the minimum size most developers accept. See zero-investment solar for factories in Chennai.
Consult your chartered accountant on how depreciation applies to your business.
What a 100 kW solar quote should include
- Panel make, model, wattage and number of modules, ALMM-listed
- Inverter make, model and quantity, with warranty terms
- Structure material, galvanising thickness, height and wind-load design
- Cable sizes and makes, ACDB/DCDB, earthing and lightning protection
- An estimated annual generation figure, ideally with a performance guarantee
- Scope of approvals: TNPDCL, Electrical Inspectorate and metering
- Separate panel, inverter and workmanship warranties. See solar warranties explained
- O&M scope: cleaning frequency, preventive maintenance and monitoring
- A payment schedule linked to delivery and commissioning milestones
Comparing several bids? Use the scorecard in our guide to solar EPC contractors for factories in Chennai.
Frequently asked questions
What is the cost of a 100 kW solar plant in Chennai?
About ₹30–50 lakh in 2026, including GST, depending on panel technology, roof type, structure and inverter brand. Most quality Tier-1 projects fall around ₹35–40 lakh.
How many units does a 100 kW solar plant generate per day?
About 400 units a day on average in Chennai, or roughly 12,000 units a month and 1,40,000–1,55,000 units a year.
How much roof space does a 100 kW solar plant need?
About 8,000–10,000 sq ft of shade-free roof on metal sheets, or 10,000–12,000 sq ft on an RCC roof with elevated structures.
What is the payback period of a 100 kW solar plant?
Typically about 2.5–4 years in Tamil Nadu, depending on your tariff category, the plant cost and how much of the power you use on site. Accelerated depreciation can shorten it further.
Is there a government subsidy for a 100 kW commercial solar plant?
No. The PM Surya Ghar subsidy applies only to homes and housing societies. Businesses benefit instead through accelerated depreciation and lower electricity bills.
What is the GST on a 100 kW solar plant?
Since 22 September 2025, the effective GST on a typical solar EPC contract is about 8.9%: 5% on the 70% goods portion and 18% on the 30% services portion.
What is the price per watt for a 100 kW solar plant?
About ₹30–50 per watt in Chennai in 2026, including GST and installation.
How long does it take to install a 100 kW plant?
Installation typically takes about 3–6 weeks after materials arrive. Approvals and metering can add a few more weeks, depending on TNPDCL processing times.
Get an exact price for your 100 kW plant
Arka Solar Energy is a solar EPC company in Chennai. Share your electricity bills and roof details, and we'll send an itemised quote with a generation estimate and payback model for your site.
Prices, tariffs and savings are indicative as of October 2026 and vary by site, specification, equipment availability and tariff category. Tamil Nadu tariffs and charges are set by TNERC and may change. This guide is general information, not tax advice.