Tamil Nadu Rooftop Solar 2026: Subsidy and Net Metering
Rooftop solar in Tamil Nadu in 2026: PM Surya Ghar subsidy, TNPDCL bi-monthly slabs and free units, net metering, the network charge, and sizing tips.
Short answer: Tamil Nadu homes get the central PM Surya Ghar subsidy (up to ₹78,000); we found no state top-up. Bills are bi-monthly, and since May 2026 homes using up to 500 units per cycle get 200 units free. Net metering under TNERC's 2021 regulations carries surplus forward, but TNPDCL charges a network charge of about ₹0.32 per unit on rooftop generation up to 10 kW (under litigation). Solar pays best for homes that cross 500 units per two months (check current notification).
Subsidy
| Scheme | Amount |
|---|---|
| PM Surya Ghar, residential | ₹30,000/kW up to 2 kW, ₹18,000 for the 3rd kW, max ₹78,000 |
| PM Surya Ghar, housing societies | ₹18,000/kW, up to 500 kW (3 kW per house) |
| State top-up | None found |
Apply on pmsuryaghar.gov.in with a vendor registered for TNPDCL. See how to apply.
Residential tariff: bi-monthly slabs
Rates below are the payable domestic rates after the state's tariff subsidy, per two-month billing cycle. Check your current bill, as a July 2026 inflation-linked revision was pending.
If you use up to 500 units in the cycle:
| Units per two months | ₹/unit |
|---|---|
| 0–200 | free (since May 2026) |
| 201–400 | 4.70 |
| 401–500 | 6.30 |
If you use more than 500 units in the cycle:
| Units per two months | ₹/unit |
|---|---|
| 0–100 | free |
| 101–400 | 4.70 |
| 401–500 | 6.30 |
| 501–600 | 8.40 |
| 601–800 | 9.45 |
| 801–1,000 | 10.50 |
| above 1,000 | 11.55 |
No fixed charge and no electricity duty for domestic consumers.
The 500-unit cliff
Crossing 500 units in a cycle costs twice: you lose 100 free units and enter the ₹8.40+ slabs. Example for 700 units per cycle:
- Without solar: 300 × 4.70 + 100 × 6.30 + 100 × 8.40 + 100 × 9.45 ≈ ₹3,825 per cycle
- If solar brings net use to 500: 200 × 4.70 + 100 × 6.30 ≈ ₹1,570 per cycle
Those first 200 units removed are worth about ₹11 each. This is why sizing in Tamil Nadu should start from your bi-monthly bill.
Net metering rules
| Item | Tamil Nadu (TNERC) |
|---|---|
| Regulation | TNERC Grid Interactive Solar PV Energy Generating Systems Regulations, 2021 |
| Capacity | Up to sanctioned load, max 1 MW |
| Settlement | Billing-cycle netting with carry-forward; year-end settlement (verify) |
| Surplus rate | Not confirmed from a primary source |
| Network charge | Domestic ≤10 kW: about ₹0.32/unit on deemed generation (20% of the ₹1.60 LT network charge); above 10 kW pays more |
| Deemed generation (≤10 kW) | Lower of inverter reading or 5.04 kWh per kW per day |
| Status | Madras High Court division bench stayed a single-judge ruling against the charge (Apr 2025); TNPDCL continues billing |
Worked example: 2 kW in Chennai
- Use: 700 units per two months (350 a month)
- Generation: 2 kW × 1,486 ≈ 2,970 units a year, about 495 per cycle
- Net use falls to about 205 units per cycle: bill ≈ ₹25
- Saving ≈ ₹3,800 per cycle, about ₹22,800 a year
- Network charge ≈ 2,970 × ₹0.32 ≈ ₹950 a year
- Price about ₹1.1–1.4 lakh, minus ₹60,000 subsidy
- Simple payback ≈ 2.5–4 years
For a home using only 400 units per cycle, most units are free or at ₹4.70, so solar saves much less. Size to the units you pay for.
Practical points for Tamil Nadu
- Coastal wind and salt: Chennai and the coast are cyclone-prone. Use heavier galvanising, stainless fasteners, and a structure design checked against IS 875 (Part 3). See structure and wind.
- North-east monsoon: expect softer generation in November–December in Chennai, as well as July.
- Heat: TOPCon modules lose less in heat; keep inverters shaded.
- Coimbatore and Madurai model slightly higher yields than Chennai.
What to double-check
- Bi-monthly units and whether the home is under or over 500 per cycle
- Any July 2026 tariff revision on the current bill
- The network charge status
- The year-end surplus rate from TNPDCL
How much solar for your city
System size needed to cover a given monthly use, from long-term Global Solar Atlas yields with a 5% rooftop derate (Sunlectric Studio data, Oct 2026). Round up to whole modules and check your roof.
| City | Yield (units per kW per year) | 200 units/month | 300 units/month | 500 units/month |
|---|---|---|---|---|
| Chennai | 1,486 | 1.6 kW | 2.4 kW | 4.0 kW |
| Coimbatore | 1,513 | 1.6 kW | 2.4 kW | 4.0 kW |
| Madurai | 1,507 | 1.6 kW | 2.4 kW | 4.0 kW |
| Tiruchirappalli | 1,496 | 1.6 kW | 2.4 kW | 4.0 kW |
Going solar in Tamil Nadu: step by step
- Read the bill. Note the consumer number, tariff category, sanctioned load and phase, and add up 12 months of units. See how to read your electricity bill.
- Size to use. Divide yearly units by your city's yield (table above) and round to a practical module count. Check shadow-free roof space.
- Pick a registered vendor for TNPDCL on pmsuryaghar.gov.in and get an itemised quote. Our installer checklist lists what to ask.
- Apply on the national portal before installation. Systems up to 10 kW are exempt from a technical feasibility study under the central consumer rules, and many DISCOMs give quick or deemed approval.
- Install with DCR modules, a matched inverter, a structure designed for local wind, proper earthing, a lightning arrester and SPDs.
- Net meter and inspection. The DISCOM tests and fits the bi-directional meter and records commissioning.
- Claim the subsidy by submitting bank details on the portal.
Tamil Nadu tip: Tamil Nadu bills every two months, so double the monthly figures in the table when you compare with a bi-monthly bill, and check where the home sits against the 500-unit line.
Talk to Sunlectric
Installers in Tamil Nadu: WhatsApp +91 89567 89307 (wa.me/918956789307) for today's landed price on DCR modules, inverters and BOS from our Pune hub and partner network. Homeowners: send your TNPDCL bill and we will check whether solar takes you back under the 500-unit line. Learn net-metering design in the Academy policy module.
Related: net metering explained, solar in the monsoon.
Sources
- TN tariff and free units: The DISCOM Bill, TN tariff July 2026; The DISCOM Bill, TN; TNERC (accessed Oct 2026; slab boundaries per TNERC structure, verify on bill)
- Net metering and network charge: Blues Renewables; Tristar Energy; TNEB salient features
- PM Surya Ghar CFA: pmsuryaghar.gov.in
- Yields: Global Solar Atlas, fetched 19 Oct 2026
Questions people ask
Is there a Tamil Nadu state subsidy for rooftop solar?
We found no state top-up for residential rooftop solar in 2026. Homes get the central PM Surya Ghar subsidy of up to ₹78,000 for 3 kW. Check the current notification.
How does the 500-unit threshold affect solar savings in Tamil Nadu?
Homes using up to 500 units in a two-month cycle get 200 units free (since May 2026). Above 500, only 100 units are free and higher slabs apply. Solar that brings your net use back under 500 per cycle saves far more per unit than the average rate suggests.
What is the network charge on rooftop solar in Tamil Nadu?
TNPDCL levies a network charge on deemed rooftop generation, about ₹0.32 per unit for domestic systems up to 10 kW. It is under litigation in the Madras High Court; TNPDCL continues to bill it. Check the current position.
Which months produce the least solar in Tamil Nadu?
Chennai has softer months in both July and November–December, when the north-east monsoon brings most of its rain. Coimbatore and Madurai are steadier.