1 unit of electricity in Tamil Nadu: what it really costs.
Average and marginal cost per unit for homes under the 2026 tariff, compared with shop, factory and solar costs.
The cost of one unit of electricity in Tamil Nadu is not a single number. Homes pay nothing for the first 100–200 units and up to ₹11.55 for the most expensive ones, so the average depends on your usage. Here is the real cost at common usage levels, for businesses, and for solar.
- Per-unit cost
- Homes
- Shops
- Factories
- Solar
Effective cost of 1 unit for homes
Because the tariff is telescopic, the average cost of one unit depends on how much you use in the two-month cycle. Energy charge only, 2026 domestic tariff.
| Units per bill | Energy charge | Average ₹ per unit |
|---|---|---|
| 300 | ₹470 | ₹1.57 |
| 400 | ₹940 | ₹2.35 |
| 500 | ₹1,570 | ₹3.14 |
| 600 | ₹2,880 | ₹4.80 |
| 800 | ₹4,770 | ₹5.96 |
| 1000 | ₹6,870 | ₹6.87 |
The next unit you use costs much more than the average: ₹6.30 between 401 and 500 units, and ₹8.40–11.55 above 500.
Homes vs shops vs factories
| Category | Cost of 1 unit |
|---|---|
| Home, 300 units per bill | about ₹1.57 average |
| Home, 1,000 units per bill | about ₹6.87 average |
| Shop / office (LT commercial) | about ₹10.45 |
| Small factory (LT industrial) | about ₹8.25 |
| Large factory (HT) | about ₹7.50 plus demand charges |
What a solar unit costs
A 3 kW home system costs about ₹1,00,100 after subsidy and makes about 4,300 units a year for 25 years, which works out to roughly ₹1 per unit over its life. That is why solar pays fastest for homes above 600 units per bill and for businesses. See the full tariff or calculate your bill.
Why Goggles Energy
One engineering team from feasibility to O&M. A real engineer reviews every enquiry, sizes the system to your bill and handles the subsidy and TNPDCL (TANGEDCO) net metering. Offices in Nagercoil (HQ) and Chennai.
FAQ
What is the cost of 1 unit of electricity in Tamil Nadu?
For homes it depends on usage: about ₹1.57 per unit on average at 300 units per bill and ₹6.87 at 1,000 units, under the 2026 tariff. Shops pay about ₹10.45 and small factories about ₹8.25.
Why is my last unit so expensive?
Tamil Nadu uses telescopic slabs. Units above 500 per bill cost ₹8.40 to ₹11.55 each, and crossing 500 also removes 100 free units.
Is solar cheaper than grid electricity in Tamil Nadu?
Yes for most users above 600 units per bill and for businesses: rooftop solar works out to roughly ₹1–2 per unit over its 25-year life after subsidy.