Part of the complete guide: Solar cost (complete guide)
Quick answer
A home using 350 units a month needs about a 3 kW system, costs roughly ₹1.2 lakh after subsidy, and saves around ₹26,000–₹35,000 a year — a payback of about 4 years. Savings scale with your consumption and your slab rate.
The simple formula
Monthly units ÷ 120 ≈ system size in kW (each kW generates about 120 units a month). Annual saving ≈ units generated × your effective tariff. Use the calculator for instant results.
Three worked examples
| Home | Monthly units | System | Cost after subsidy | Year-1 saving | Payback |
|---|---|---|---|---|---|
| Small family | 200 | 2 kW | ≈ ₹0.7 lakh | ≈ ₹14,000–₹18,000 | ~4–5 yrs |
| Typical family with AC | 350 | 3 kW | ≈ ₹1.2 lakh | ≈ ₹26,000–₹35,000 | ~3.5–4.5 yrs |
| Large villa / EV | 600 | 5 kW | ≈ ₹2.1 lakh | ≈ ₹45,000–₹60,000 | ~3.5–4.5 yrs |
Higher consumption pushes you into costlier slabs, so every unit solar replaces is worth more — that is why bigger households see faster payback.
What you will still pay
Fixed charges, electricity duty and any minimum charge remain. Solar reduces energy charges. Expect your bill to fall by 80–95%, not to zero.
Factors that change the result
- Shading from coconut palms or neighbouring buildings
- Tilt and orientation (south-facing at 10–15° is ideal in Kerala)
- Cleaning — dirty panels lose 5–20%
- Daytime consumption — net metering reduces this concern but self-consumption still helps
Always verify. Subsidy, tariff and price figures change. Confirm with the official portal, KSEB/TNPDCL and a written quote before paying any advance. Figures here are indicative for South Kerala & Kanyakumari.
