On This Page
Quick answer: A quality on-grid rooftop system with DCR panels costs about ₹1,80,000 for 3 kW, ₹3,00,000 for 5 kW and ₹5,60,000 for 10 kW installed in Tamil Nadu. After the combined ₹1,00,000 subsidy (₹78,000 PM Surya Ghar + ₹22,000 state top-up under G.O. 102), you pay roughly ₹80,000, ₹2,00,000 and ₹4,60,000. Sized to your actual bill, each pays back in about 3–3.5 years. The wrong size can stretch that past 7 years.
The Side-by-Side
| 3 kW | 5 kW | 10 kW | |
|---|---|---|---|
| Installed price (on-grid, DCR panels) | ₹1,80,000 | ₹3,00,000 | ₹5,60,000 |
| PM Surya Ghar (central) | – ₹78,000 | – ₹78,000 | – ₹78,000 |
| Tamil Nadu top-up (G.O. 102) | – ₹22,000 | – ₹22,000 | – ₹22,000 |
| Net cost | ₹80,000 | ₹2,00,000 | ₹4,60,000 |
| Net cost per kW | ₹26,700 | ₹40,000 | ₹46,000 |
| Units per 2-month cycle | ~750 | ~1,250 | ~2,500 |
| Roof area needed (shadow-free) | ~300 sq ft | ~500 sq ft | ~1,000 sq ft |
| Panels (≈545 W each) | 6 | 9–10 | 18–19 |
| Supply needed | Single-phase OK | Three-phase usually | Three-phase |
The subsidy stops at 3 kW. Both the central and state subsidies cap out at 3 kW, so every kilowatt above that is paid at full price. That's why net cost per kW rises from about ₹27,000 at 3 kW to ₹46,000 at 10 kW. Prices are our current Tamil Nadu installed rates, the same figures our solar calculator uses. Low-cost quotes using non-DCR panels can look ₹20,000–₹40,000 cheaper, but they won't qualify for subsidy.
Which Size Fits Your Bill
Each size makes about 250 units per kW in a two-month billing cycle (see units per day per kW). Match that to the units on your bill, not the rupees.
| Bi-monthly units on your bill | Bi-monthly energy charge (approx.) | Right size |
|---|---|---|
| 500–800 | ₹1,570–₹4,770 | 3 kW |
| 800–1,000 | ₹4,770–₹6,870 | 3–4 kW |
| 1,000–1,400 | ₹6,870–₹11,500 | 5 kW |
| 1,400–2,000 | ₹11,500–₹18,400 | 6–8 kW |
| 2,000–2,600 | ₹18,400–₹25,400 | 10 kW |
Energy charges are calculated on the TANGEDCO domestic telescopic slabs, excluding fixed charges.
Payback When Sized Right
| 3 kW | 5 kW | 10 kW | |
|---|---|---|---|
| Typical household | 750 units/2 months | 1,250 units/2 months | 2,500 units/2 months |
| Bi-monthly bill before solar | ~₹4,300 | ~₹9,750 | ~₹24,200 |
| Annual saving | ~₹25,800 | ~₹58,500 | ~₹1,45,000 |
| Net cost | ₹80,000 | ₹2,00,000 | ₹4,60,000 |
| Simple payback | ~3.1 years | ~3.4 years | ~3.2 years |
Bigger systems don't pay back slower even though they get less subsidy per kW. The households that need them pay ₹9.45–₹11.55 per unit in the top slabs, so each unit of solar saves more.
Payback When Sized Wrong
Oversized: a 5 kW system on a 750-unit bill. You can't save more than your bill. Annual saving stays at about ₹25,800, but net cost is ₹2,00,000. Payback stretches to about 7.8 years, and surplus units bank with TANGEDCO without becoming cash.
Undersized: a 3 kW system on a 1,250-unit bill. Solar cuts net consumption to about 500 units. That restores the 200 free units, since TANGEDCO's larger free allowance only applies at 500 units or below. The bill drops from about ₹9,750 to about ₹1,570. Annual saving is about ₹49,000 on an ₹80,000 investment, paying back in about 1.6 years.
That second case is the best-returning solar purchase in Tamil Nadu right now. If roof space or budget limits you, a 3 kW system that brings you to 500 units or below often beats a bigger one on return per rupee. You give up some lifetime savings, not payback speed.
Hidden Costs by Size
- Three-phase conversion. Most 5 kW and all 10 kW systems need a three-phase connection. If you're single-phase, budget for phase conversion and possibly a sanctioned load increase.
- Elevated structure. If you need the terrace usable underneath, raised structures add cost per kW. See elevated solar structures.
- Hybrid or battery. Adding battery backup raises gross cost by roughly 50–70%. Subsidy still applies to grid-connected hybrids. See on-grid vs hybrid ROI.
- Maintenance. PM Surya Ghar installs include five years of vendor maintenance; after that, see solar AMC cost.
- Cash flow. Both subsidies are reimbursed after commissioning, so you pay the full installed price first. Size any solar loan against the gross price, not the net.
FAQ
What is the price of a 3 kW solar system in Tamil Nadu after subsidy?
About ₹80,000 for a quality on-grid system: ₹1,80,000 installed, minus ₹78,000 PM Surya Ghar and ₹22,000 Tamil Nadu state subsidy under G.O. 102. You pay the full amount first and receive both subsidies in your bank account after commissioning.
What is the price of a 5 kW solar system in Tamil Nadu?
About ₹3,00,000 installed, or roughly ₹2,00,000 after the combined ₹1,00,000 subsidy. The subsidy doesn't increase beyond 3 kW, so the extra 2 kW is unsubsidised.
What is the price of a 10 kW solar system in Tamil Nadu?
About ₹5,60,000 installed for a residential on-grid system, or roughly ₹4,60,000 after the ₹1,00,000 combined subsidy. A 10 kW system needs a three-phase connection and about 1,000 sq ft of shadow-free roof.
Is a 5 kW solar system enough for a house with 2 ACs?
Usually, yes. Two 1.5-ton inverter ACs running six to eight hours a day typically add 400–600 units to a two-month bill. A household at 1,000–1,400 bi-monthly units is a good fit for 5 kW. See running a 1.5-ton AC on solar.
Should I install 3 kW or 5 kW solar?
Install whichever brings your net consumption closest to zero, or at least below 500 units every two months. Divide your average bi-monthly units by 250 to get the kW you need. If roof or budget won't stretch, 3 kW that gets you under 500 units still pays back fast.
Sources & Updates
- Tristar pricing: installed prices are Tristar Energy's current Tamil Nadu rates for on-grid systems with DCR-compliant panels (November 2026), the same figures as our solar calculator. They're our rates, not a government benchmark. Other installers' quotes will differ.
- PM Surya Ghar national portal: central subsidy of ₹30,000/kW for the first 2 kW and ₹18,000 for the 3rd kW, capped at ₹78,000.
- G.O. (Ms) No. 102, Energy Department, Government of Tamil Nadu, dated 19 September 2026: the state top-up of ₹5,000 / ₹10,000 / ₹22,000, disbursed by TEDA. Summary and eligibility in our G.O. 102 guide.
- Tamil Nadu Electricity Regulatory Commission (TNERC): tariff orders behind the domestic telescopic slab rates used in the bill calculations. Slab tables are in our TANGEDCO tariff guide.
- Tristar calculations: bill and payback figures count energy charges only, exclude fixed charges, and assume net metering offsets imported units 1:1.
The state top-up is limited to the first 1,00,000 eligible applicants. Confirm current subsidy status on the portal before purchase. Current tariff and subsidy figures are kept on our Tamil Nadu solar tariff & subsidy tracker.
Last verified: 5 November 2026.
Ready to Go Solar?
Get a personalized solar quote based on your electricity consumption and roof area.
Related Articles
₹78,000 Solar Subsidy Tamil Nadu | 2026 Step Guide
A complete, step-by-step walkthrough of claiming the ₹78,000 PM Surya Ghar solar subsidy in Tamil Nadu — plus the ₹22,000 state top-up under G.O. 102 that takes the total to ₹1 lakh — from registration on pmsuryaghar.gov.in to money in your bank account.
Solar Subsidy Rejected? 8 Common Reasons and How to Fix Them (2026)
Learn the 8 most common reasons PM Surya Ghar subsidy applications get rejected in Tamil Nadu — and the exact steps to fix each issue and get your subsidy approved.
Zero Electricity Bill with a 3kW Solar System
Real numbers, real savings — see exactly how a 3kW rooftop solar system in Tamil Nadu eliminates your electricity bill and pays for itself in just 3 years after subsidy.