How does TNEB's bi-monthly billing cycle affect solar ROI?

TNEB bills every 2 months. Your consumption is totalled over 2 months and pushed through progressive slabs. More consumption = higher slab = higher per-unit cost. Solar reduces your net units before this slab calculation, meaning you may drop from the ₹5.50/unit slab to the ₹3.00 slab — a massive bi-monthly saving amplifier.

How many solar panels do I need for a 3 kW system in Chennai?

A 3 kW system typically requires 8–10 solar panels (330W–375W each). Each panel needs about 25–30 sq.ft. of shadow-free rooftop. So you need approximately 200–300 sq.ft. for a 3 kW system — achievable in most Chennai independent homes and first-floor flats with terrace access.

What is TNEB net feed-in metering and how are credits calculated?

When your solar plant generates more than you consume, excess units are fed to the TNEB grid. TNEB installs a bidirectional meter. Excess units are credited at ₹2.00/unit on your next bi-monthly bill. This "TNEB Net Feed-in" mechanism means your system effectively earns money during peak sunshine hours when you're not at home.

Which solar companies are MNRE-empanelled in Tamil Nadu?

You must install through MNRE-empanelled vendors to qualify for the PM Surya Ghar subsidy. Key TNPEDP-registered vendors in TN include: Waaree Energies, Adani Solar, Jakson Solar, and several state-specific EPC companies. Always verify vendor registration on the pmsuryaghar.gov.in portal before signing any contract.

How do I calculate my solar system size using my TNEB bill?

Look at your TNEB bi-monthly bill for "Units Consumed." Divide by 2 for monthly units. Then: Monthly kWh needed ÷ (Daily sun hours × 30 × 0.8 efficiency) = System kW needed. For Coimbatore (5.8 sun hrs), 600 monthly units ÷ (5.8 × 30 × 0.8) = ~4.3 kW recommended. Our calculator above does this automatically.

Is a solar system worth it in Chennai despite coastal humidity?

Yes — though you must factor in a 5% efficiency loss due to sea-salt soiling (the "Shadow Factor"). Chennai averages 5.4 peak sun hours/day, which is still excellent. With PM Surya Ghar's ₹78k subsidy on a 3 kW system, the break-even is typically 3.5–4 years — still a strong investment with 20+ years of free electricity ahead.

Can I apply for solar subsidy if I live in a flat/apartment in Chennai?

Yes, apartment residents can apply for group net-metering or individual rooftop systems if your building has terrace access and your flat has a sanctioned TNEB connection. You need Resident Welfare Association (RWA) approval and proportional rooftop allocation. Group net-metering allows up to 500 kW for housing societies.

LIVE 2026 — TNEB Tariff & Subsidy Updated

Tamil Nadu — TNEB Solar Audit Tool

Tamil Nadu Solar Calculator 2026: TNEB Bill Savings Audit

Stop paying high TNEB bills. Master your solar utility with our 2026 Tamil Nadu-specific calculator—factoring in local tariffs, PM-Surya Ghar subsidies, and net-metering benefits.

TNEB Bi-Monthly

Billing Optimised

5.5 hrs/day

TN Sunshine Avg.

PM Surya Ghar

2026 Rates

Net-Metering

Feed-in Included

Audit My TNEB Bill Surya Ghar Guide

TN Solar Payback Snapshot

Based on Chennai/Coimbatore avg. household

Avg. TNEB Monthly Bill

₹3,000

Recommended Plant

3 kW

Estimated Subsidy

₹78,000

Break-even Point

3.5 Years

3 kW ROI Projection — Tamil Nadu

Year 1

₹36,000

Year 2

₹72,000

Year 3

₹1,08,000

Break-even

3.5 Yrs

Year 10

₹2,52,000

25-Year Net

₹7.5 Lakh+

Assumes ₹3k/mo bill, 3kW system @ ₹78k subsidy, 5.5 sun hrs/day, TNEB ₹5.50/unit

Net-Metering Ready

The Billion-Rupee TNEB Insight

Why TNEB's Bi-Monthly Billing is Your Solar Superpower

Most Indians get monthly bills. TNEB charges you every 2 months — and this single fact dramatically changes your solar ROI calculation.

The "Bi-Monthly Benefit" Explained

TNEB bills you for 2 months of consumption at once. This means your slab calculation is done on 2 months of units — pushing most Chennai households into the costly ₹5.50–₹7.00/unit slab instead of the cheaper lower slabs.

Example: 300 units/month household

Bi-monthly consumption:600 units

Units hitting ₹5.5 slab:100 units × ₹5.50

Bi-Monthly Bill:₹1,665

A 3 kW solar plant generates ~594 kWh/2 months, which slashes your consumption before slab calculation — dropping you from the ₹5.50 slab back to ₹0–₹3.00 slabs. That's the bi-monthly compounding advantage.

Why 3 kW is the "Sweet Spot" for TN

For most Chennai and Coimbatore households consuming 400–600 units/month, the 3 kW plant hits three key sweet spots simultaneously:

Maximum PM Surya Ghar Subsidy

₹78,000 — the highest bracket, giving the best value/rupee on subsidy.

Generation Matches Consumption

3 kW × 5.5 hrs × 30 × 0.8 = ~396 kWh/month, covering most households.

Rooftop Fit

Requires only 240 sq.ft — achievable in most Madurai/Salem independent homes.

Fastest Payback

Net cost ~₹1.17L with ₹36k annual savings = 3.25-year payback in TN.

TNEB Tariff Slabs 2026

Bi-monthly domestic tariff. Solar reduces units before slab calculation — your biggest financial lever.

0–100 units

FREE

101–200 units

₹1.50/unit

201–500 units

₹3.00/unit

501–1000 units

₹5.50/unit

Above 1000 units

₹7.00/unit

Note: TNEB first 100 units per 2-months FREE for domestic consumers (BPL). Above 200 units: slabs are cumulative.

TN-Specific Calculator

TNEB Solar System Sizer & ROI Calculator

Enter your bi-monthly TNEB units and rooftop space. We'll calculate your ideal plant size, subsidy, and 25-year savings.

TNEB Consumption Details

Bi-Monthly Units Consumed (from TNEB bill)

Look at your bi-monthly TNEB bill under "Units Consumed"

kWh/2mo

100 units1,0003,000 units

Est. bi-monthly bill: ₹800 | Monthly avg: 300 kWh

Your City / Region

Chennai gets 5.4 peak sun hours/day — excellent for solar ROI

Rooftop Details

Available Shadow-Free Rooftop Area

Measure the flat, unshaded area. Each kW needs ~80 sq.ft.

sq.ft.

80 sq.ft5002,000 sq.ft

Max. installable: 3 kW | ~12 solar panels

2026 PM Surya Ghar Subsidy Tiers

Up to 1 kW

45%₹30,000

1 kW – 2 kW

40%₹60,000

2 kW – 3 kW+

35%₹78,000

Government Scheme

How to Apply for PM Surya Ghar in Tamil Nadu

TNEB (TANGEDCO) is the nodal agency for net-metering and meter installation. Here is the exact Tamil Nadu-specific process.

STEP 01

Register on the Portal

Visit pmsuryaghar.gov.in and register with your TNEB consumer number, Aadhaar, and mobile number. Select "Tamil Nadu" as your state.

STEP 02

Get TNEB Feasibility Approval

TNEB (TANGEDCO) reviews your application and approves feasibility based on your grid capacity and rooftop area. Usually takes 7–15 days.

STEP 03

Install with MNRE-Empanelled Vendor

Choose only MNRE-empanelled solar vendors in Tamil Nadu to qualify for subsidy. Compare 3 quotes from TNPEDP-registered installers.

STEP 04

TNEB Bidirectional Meter Installation

After installation, TNEB inspects and installs a net-metering bidirectional meter. This enables "feed-in" credits on your bi-monthly bill.

STEP 05

Upload Documents & Claim Subsidy

Upload installation photos, vendor invoice, and TNEB meter certificate on the portal. Subsidy is directly credited to your bank account.

TNEB Net Feed-in Metering Details

Under Tamil Nadu's net-metering policy, excess units your solar plant feeds into the TNEB grid are credited on your next bi-monthly bill. The feed-in tariff is currently at ₹2.00/unit for export beyond consumption.

Metering TypeBidirectional (Net-Energy Meter)

Feed-in Credit₹2.00/unit (export surplus)

Minimum System Size1 kW (residential)

Max Capacity Allowed80% of sanctioned load

TNEB Approval SLA30 days from application

Documents Required for TN Application

Latest TNEB Electricity Bill

Aadhaar Card (applicant)

Bank Account Passbook (1st page)

Rooftop Photos (before installation)

MNRE-empanelled Vendor Invoice

Installation Completion Certificate

TNEB Inspection Report

Ready to Apply? Open Applications in Tamil Nadu

Budget of ₹75,021 crore is allocated. First-come, first-served. Act before your district quota fills up.

Apply at pmsuryaghar.gov.in

Authority Insight

The "Shadow Factor" — TN's Hidden ROI Killer

Tamil Nadu's coastal and semi-arid climate brings two invisible ROI thieves that most online calculators ignore: dust accumulation and high humidity-induced soiling. Our calculator already applies a 5% efficiency deduction for this.

Coastal Dust & Sea Salt Deposits

Chennai, Pondicherry, and coastal TN plants lose 3–8% efficiency from salt-laden air depositing on panels monthly. Without cleaning, annual output drops by up to 15%.

Humidity-Induced Panel Soiling

Monsoon humidity (June–October) causes bio-fouling (algae/moss) on panels, especially in Coimbatore and Nilgiris regions. A once-monthly dry wipe can recover 5–6% efficiency.

The 5% Cleaning Efficiency Rule

Always factor a 5% efficiency loss in TN ROI calculations to be conservative. Our calculator uses 80% system efficiency (including this buffer) vs. the 85% used by some vendors.

Desi Utility Tip: Schedule a soft-brush dry clean every 3–4 weeks. In Chennai coastal areas, add a monthly rinse. This alone can improve your annual yield by 8–12%.

TN City-wise Solar Performance

Tirunelveli5.9 hrs/day · 94% yield score

Coimbatore5.8 hrs/day · 92% yield score

Madurai5.7 hrs/day · 91% yield score

Salem / Namakkal5.6 hrs/day · 90% yield score

Tiruchi5.6 hrs/day · 89% yield score

Chennai (coastal)5.4 hrs/day · 85% yield score

Vellore / Northern TN5.3 hrs/day · 84% yield score

Yield scores include 5% shadow/dust deduction (TN-specific) applied to raw irradiance data. Coastal cities penalised for salt soiling.

Photovoltaic Efficiency Utility: Panel Grade Matters

In high-humidity TN, always specify Tier-1 mono-PERC or TOPCon panels (Jinko, LONGi, Adani) with anti-soiling coating. They maintain efficiency 4–6% better than standard poly panels in coastal conditions.

Expert Q&A

Tamil Nadu Solar FAQ 2026

TNEB-specific questions answered by our renewable energy consultants

For Tamil Nadu residents, the central government provides: ₹30,000 for 1 kW, ₹60,000 for 2 kW, and a flat ₹78,000 for 3 kW and above. There is no additional state-specific top-up in TN currently, but the central subsidy alone is highly valuable given TN's excellent solar irradiance.

Your Solar Research Hub

More Tools for Your TN Solar Journey

These tools work together to give you the complete picture before committing to solar in Tamil Nadu.

Global Solar ROI Calculator

Compare this with our master Solar ROI calculator — covers all Indian states with advanced projections.

TNEB Bill Calculator

Understand your current TNEB slab before switching to solar. Accurate bi-monthly slab calculation.

Best Solar AC in India

Don't forget the AC impact on solar sizing. AC is TN's #1 power consumer — pick the right model.

Battery Backup Calculator

Going off-grid? Calculate your battery size for Chennai's 8–12 hour outage scenarios.

Net Metering Calculator

Calculate TNEB net feed-in credits. See how much your grid export earns you bi-monthly.

PM Surya Ghar Subsidy Calculator

Detailed 22-state subsidy calculator with state top-up amounts and payback period comparison.