Solar Calculator for Kerala & Tamil Nadu: cost, subsidy & savings
Enter your monthly electricity bill and get the recommended system size, PM Surya Ghar subsidy, payback period and 25-year savings — instantly and free.
Your details
Your solar estimate
*Subsidy applies to residential households. Tamil Nadu homes of 3 kW and above also get the announced ₹22,000 state top-up (verify on the TNPDCL portal). In Kerala, systems above 3 kW (5 kW with battery) are reported to fall under net billing, where exports earn far less than your retail tariff, so size to your daytime use. Institutions may use RESCO/OPEX or depreciation. Estimates are indicative.
Get a firm quote for this system →Assumptions behind the numbers
| Input | Value used | Why |
|---|---|---|
| Generation | Kerala 4.0, Kanyakumari 4.25 kWh per kW per day | Typical after monsoon and temperature losses; Kanyakumari has higher irradiation. |
| Sizing goal | Bill taken to about zero | System sized so yearly generation offsets billable units. Only fixed charges (Kerala about ₹150/month) remain. |
| Tariff | Kerala ₹7.0/unit, Tamil Nadu ₹6.5/unit; first 50 units/month free in Tamil Nadu | Effective averages for typical household slabs. Edit the tariff field to match your bill. |
| Kerala export credit | Net metering up to 3 kW; above that net billing, 70% daytime own-use, exports at ₹2.8/unit | Reported KSERC 2025 rules; confirm current limits with KSEB. This makes larger Kerala systems cost more per unit saved. |
| System cost | ₹62,000/kW (≤3 kW), ₹58,000 (≤5 kW), ₹55,000 (≤10 kW) | Indicative turnkey price for DCR panels, inverter, structure, wiring, net-meter paperwork. |
| Home subsidy | ₹30,000/kW for first 2 kW + ₹18,000 for the 3rd kW (max ₹78,000); +₹22,000 in Tamil Nadu for 3 kW+ | PM Surya Ghar central assistance; Tamil Nadu state top-up announced in the 2026 revised budget. |
| Roof space | ~10 sq m (≈108 sq ft) per kW | Shadow-free area incl. walkways. |
| Degradation / tariff rise | 0.7% per year / 3% per year | Typical module warranty curve and long-run tariff trend. |
Want an exact figure? A site visit checks shading, roof strength, sanctioned load and the right inverter. Book the Solar Advisor service or request a free quote.
How the solar calculator works
How accurate is the solar calculator?
It gives a realistic planning estimate using typical South Kerala/Kanyakumari generation (about 4 kWh per kW per day), current subsidy rules and indicative market prices. A site visit refines it for shading, roof orientation and sanctioned load.
How is the recommended system size calculated?
We convert your monthly bill to units using your tariff, divide by expected monthly generation per kW (~120 units), round to the nearest 0.5 kW, and cap by your roof area if you provide it.
Does the calculator include battery storage?
No. It models an on-grid system with net metering, the most economical option in Kerala and Tamil Nadu. Batteries add roughly ₹40,000–₹70,000 per kWh-class hybrid setup and lengthen payback.
Why does my result differ from an installer's quote?
Quotes vary with panel brand, inverter, structure height, cabling distance and whether the price is inclusive of GST, net-metering fees and transport. Ask for an itemised bill of material.