Tamil Nadu has one of India’s most straightforward rooftop solar structures: a single distribution company (TANGEDCO) serves the entire state under TNERC regulation. There are no multi-DISCOM territory complexities — every application goes through TANGEDCO, using the same portal and the same process. The state’s APPC rate is among the higher nationally, which improves rooftop solar economics for Tamil Nadu consumers.
TNERC Net Metering Regulations
The Tamil Nadu Electricity Regulatory Commission (TNERC) issues net metering regulations that TANGEDCO implements. Key provisions:
Residential net metering: Up to the consumer’s sanctioned load. A household with a 5 kW sanctioned load can install up to 5 kW.
Commercial net metering: Up to 1 MW under standard TNERC net metering. Above 1 MW, open access with wheeling charge applies.
Export rate: TANGEDCO’s APPC, set annually by TNERC. At approximately Rs. 4.00–4.50 per unit, Tamil Nadu’s APPC is among the higher rates nationally — reflecting the state’s power procurement from expensive sources including long-term PPAs.
Settlement period: Monthly in Tamil Nadu. Unlike annual-settlement states, surplus credits in any billing month are settled in that month at APPC and do not carry forward. This makes Tamil Nadu’s economics more sensitive to month-to-month generation variability.
TANGEDCO: The Sole DISCOM
TANGEDCO (Tamil Nadu Generation and Distribution Corporation Limited) handles all electricity distribution across Tamil Nadu’s 38 districts. For rooftop solar installers, this single-DISCOM structure means:
- One application portal
- One set of application requirements
- Consistent processing standards across the state
Application process: Through TANGEDCO’s online consumer portal. Submit:
- Service connection number
- Load sanction letter
- Site plan with rooftop layout
- Single-line diagram
- Module and inverter BIS certificates
- ALMM compliance declaration (for PM Surya Ghar)
- Proof of ownership
- Application fee
Processing: TANGEDCO aims to provide technical sanction within 30 days for straightforward applications. In Chennai urban areas and Coimbatore where solar penetration is high, transformer checks may cause delays or size reductions.
TEDA: Vendor Empanelment and PM Surya Ghar
TEDA (Tamil Nadu Energy Development Agency) is the state nodal agency for renewable energy. For PM Surya Ghar in Tamil Nadu:
- Vendor empanelment: TEDA coordinates with TANGEDCO to empanel vendors on the national portal. Installers must have TEDA’s validation to be listed for PM Surya Ghar in Tamil Nadu
- Quality oversight: TEDA monitors empanelled vendor performance and can delist underperforming contractors
- State awareness: TEDA runs consumer awareness programmes for PM Surya Ghar eligibility and the subsidy application process
Green Tamil Nadu Mission Solar Targets
The Tamil Nadu government’s Green Tamil Nadu Mission sets solar capacity targets as part of a broader sustainability framework. Tamil Nadu has historically been a solar leader — it was among the first states to exceed 1,000 MW of solar capacity.
Current targets under state policy include:
- 20,000 MW of solar capacity by 2030
- Significant rooftop solar contribution from residential, commercial, and institutional segments
- Grid integration challenges as solar penetration increases — motivating TANGEDCO’s transformer upgrade programme
Accelerated Depreciation for Commercial Solar
For commercial and industrial consumers in Tamil Nadu, Accelerated Depreciation (AD) under the Income Tax Act is a significant financial benefit:
| Parameter | Standard Depreciation | With Accelerated Depreciation |
|---|---|---|
| First-year depreciation | 15% | 40% |
| Rs. 10 lakh system investment | Rs. 1.5 lakh depreciation | Rs. 4.0 lakh depreciation |
| Tax saving (30% tax rate) | Rs. 45,000 | Rs. 1,20,000 |
| Additional first-year tax saving | — | Rs. 75,000 |
Accelerated Depreciation applies to the total system cost (before GST input credit recovery). The effective system cost for a tax-paying commercial entity is reduced by both GST input credit and AD tax savings — sometimes bringing the effective cost down by 25–35%.
When creating solar proposals for Tamil Nadu commercial customers, including the AD calculation alongside net metering savings converts significantly better than presenting only the bill savings figure.
Open Access Solar in Tamil Nadu
For commercial and industrial consumers above the 1 MW net metering threshold, Tamil Nadu offers open access:
Wheeling charges: Consumers using TANGEDCO’s grid to wheel power from an off-site solar plant (or a rooftop above 1 MW) pay wheeling charges set by TNERC. These charges partially offset the economics of larger installations.
Cross-subsidy surcharge: Large consumers switching to open access solar also face a cross-subsidy surcharge in Tamil Nadu. The TNERC calculates this annually — it is a significant component of open access economics.
Who uses it: Large manufacturing units, IT parks, and data centres in Chennai, Coimbatore, and Hosur with electricity bills above Rs. 5–10 lakh/month are typical open access solar candidates.
Pro Tip: Higher APPC Means Stronger Residential Economics in Tamil Nadu
Tamil Nadu’s APPC of Rs. 4.00–4.50/unit is among India’s highest. For a 3 kW residential system generating 450 units/month and consuming 300 units, the 150-unit surplus earns Rs. 600–675 in net metering credits — meaningfully more than in lower-APPC states. When demonstrating PM Surya Ghar economics using solar design software, this higher credit rate should be prominently shown in the proposal.
Design Tamil Nadu Rooftop Projects with TANGEDCO-Ready Documentation
SurgePV generates single-line diagrams, ALMM compliance declarations, and TEDA-compatible commissioning documentation for Tamil Nadu rooftop solar applications.
Book a DemoNo commitment required · 20 minutes · Live project walkthrough
Frequently Asked Questions
What is the TANGEDCO export rate?
Approximately Rs. 4.00–4.50 per unit (TNERC APPC, revised annually) — among the higher rates nationally. Monthly settlement applies.
How do I apply for net metering?
Through TANGEDCO’s online consumer portal with service connection number, load sanction, SLD, equipment BIS certs, and ALMM declaration. Processing takes approximately 20–40 days for technical sanction.
What is TEDA?
Tamil Nadu Energy Development Agency — the state nodal body for renewable energy, responsible for vendor empanelment, PM Surya Ghar coordination, and state solar programme oversight.
Is Accelerated Depreciation available?
Yes — 40% first-year depreciation on solar system cost under the Income Tax Act. Available to commercial and industrial entities across India including Tamil Nadu.
