What is a realistic starting budget?
For initial planning, this site uses ₹70,000–₹85,000 for 1 kW, ₹1.30 lakh–₹1.55 lakh for 2 kW, and ₹1.80 lakh–₹2.20 lakh for 3 kW before potential subsidies. A larger system is modelled at ₹55,000–₹70,000 per kW. These are indicative ranges, not a binding Arc Solar quotation.
| Capacity | Before subsidy | Modelled roof space |
|---|---|---|
| 1 kW | ₹70,000–₹85,000 | ~110 sq ft |
| 2 kW | ₹1.30 lakh–₹1.55 lakh | ~220 sq ft |
| 3 kW | ₹1.80 lakh–₹2.20 lakh | ~330 sq ft |
| 5 kW | ₹2.75 lakh–₹3.50 lakh | ~550 sq ft |
The 1–3 kW ranges follow the Tamil Nadu rooftop solar portal. The larger-system allowance is an estimate used by this calculator. A site survey and equipment specification determine the written price.
Size the system from units, then check your budget
Use the units consumed on your electricity bill, not the rupee total. A home using 720 units over two months averages 360 units per month. At the calculator’s planning assumption of 120 units generated per kW per month, that suggests a 3 kW system.
A suggestion is not an obligation. If 2 kW fits your budget better, choose 2 kW. Your generation, potential subsidy, roof requirement and savings should be recalculated for that choice. Roof suitability, daytime consumption and the electricity connection are checked before finalising capacity.
Subsidies do not remove the upfront funding requirement
An eligible 3 kW residential system could receive up to ₹78,000 centrally and ₹22,000 from Tamil Nadu under the dated scheme conditions used here. The combined potential support is ₹1.00 lakh, but approval, beneficiary allocation and commissioning requirements apply.
Budget for the full installation cost before the assistance is paid. Commercial projects do not qualify for these household subsidies. Read the eligibility guide and official sources before counting assistance in your budget.
What should a written quotation include?
- Panel and inverter makes, model numbers, rated capacity and warranty terms.
- Mounting structure, electrical protection, earthing, cabling and installation scope.
- Taxes, statutory charges, approvals and metering responsibilities.
- Any additional roof work, cable runs, access equipment or structural work.
- Battery and backup equipment as separate items where requested.
- Payment stages, commissioning conditions and the service contact.
A low headline price is difficult to compare if the equipment or exclusions differ. Ask for the same specification from each installer.
Why savings are different for every roof
The estimator models 70% direct self-consumption and compares energy charges before and after solar. It includes Tamil Nadu domestic free-unit benefits, excludes export credits and does not assume grid exports earn the retail electricity rate. Fixed charges and some other bill components may remain.
A household already within its free-unit allowance may show no energy-bill savings in this model. Shading, available roof area, actual generation and when you use power can all change the result. A budget estimate helps start the conversation; it is not a guarantee of generation or payback.
Tariff reference: official Tamil Nadu tariff schedule, checked 28 October 2026.