One of the most common things I hear from homeowners after we commission their system: "I wish I had known what to expect at each stage." The solar installation process involves multiple agencies — your installer, TANGEDCO, the national subsidy portal, equipment manufacturers — and understanding the sequence demystifies the timeline and prevents frustration.

This is the complete, unfiltered guide to how a residential solar installation in Tamil Nadu actually unfolds, from the first phone call to the day your net meter goes live.

Stage 1: Initial Consultation and Energy Audit

Typical duration: 1–2 days

Everything begins with understanding your energy consumption. A credible solar installer will never quote you a system size without first analysing your electricity bills.

What happens in this stage:

Review of your last 12 months of electricity bills to identify monthly consumption patterns (summer peaks, monsoon dips)
Discussion of your future load additions: EV charging, additional AC units, water heaters
Understanding your financial goals: maximum self-consumption, subsidy optimisation, or grid export income
Preliminary system size recommendation based on consumption, available roof space, and budget

What you should provide: Your last 3–4 electricity bills and approximate roof area (a rough floor plan or Google Maps screenshot helps).

Red flag: Any installer who quotes a system without asking about your bills is guessing.

Stage 2: Site Assessment

Typical duration: Half day to 1 day on-site

A physical visit to your property by a qualified solar engineer is non-negotiable. No remote assessment using satellite images alone can replace this.

Roof Survey

Measurement of available roof area and orientation (south-facing surfaces are optimal in Tamil Nadu; east-west configurations work well for flatter generation curves)
Roof material assessment: RCC terrace, Mangalore tiles, metal sheets, or tin — each requires different mounting approaches
Structural load calculation: Solar panels plus mounting structure typically add 15–25 kg/m² to your roof; older structures may need reinforcement

Shading Analysis

Using tools like SunEye, Solar Pathfinder, or digital shading software, the engineer maps shadows from adjacent buildings, water tanks, trees, and chimneys across different hours and seasons
Shading is the single biggest efficiency killer in urban Indian rooftops — even 10% shading on one panel can reduce a string's output by 30–40% with conventional string inverters

Electrical Assessment

Location of your main distribution board (DB) and existing wiring condition
Phase of supply (single-phase 230V or three-phase 415V) determines maximum inverter capacity
Earthing continuity test of existing system — poor earthing is extremely common in older Tamil Nadu buildings and must be remediated before solar installation

Single-Line Diagram (SLD)

The engineer prepares a preliminary Single-Line Diagram showing panel array configuration, inverter placement, AC/DC cable routing, protection devices (MCBs, SPDs, fuses), earthing, and grid connection point. This document is required for TANGEDCO application.

Stage 3: System Design and Proposal

Typical duration: 2–3 days

Using site survey data, your installer prepares:

Final system design: Panel wattage and count, inverter make and model, mounting structure type, cable sizing calculations
Generation estimate: Using PVGIS or PVSyst simulation with local irradiation data for your district — expressed as units per day and annually
Financial analysis: Total cost, applicable subsidies (PM Surya Ghar Yojana), payback period, 25-year savings projection
Equipment specifications: Datasheets for all major components

Review this proposal carefully. Ask about panel efficiency, inverter warranty, and the basis for generation estimates. A reputable installer uses actual local irradiation data, not national averages.

Stage 4: TANGEDCO/DISCOM Application

Typical duration: 7–30 days depending on feeder load

Before any installation work begins, the grid connection must be formally applied for. This step is often the longest and most bureaucratic part of the process.

Net Meter Application

Your installer submits an application to the relevant TANGEDCO subdivision office with:

Completed application form (Form A or equivalent as per Tamil Nadu Solar Policy)
Single-Line Diagram signed by a licensed electrical contractor
Copy of your electricity bill
Property ownership proof
Technical specifications of panels and inverter

Technical Feasibility Assessment

TANGEDCO engineers evaluate whether the distribution transformer serving your area has sufficient capacity to accept solar export. In congested feeders with high existing solar penetration, this can be the bottleneck. Typical response: 7–15 working days in urban areas; up to 30 days in rural subdivisions.

Feasibility Approval

Upon approval, TANGEDCO issues a feasibility letter specifying approved capacity. Installation must not begin before this letter is received — particularly if you are applying for PM Surya Ghar Yojana subsidy, as pre-installation voids the subsidy.

Stage 5: Procurement

Typical duration: 3–7 days after approval

With approvals in hand, your installer procures equipment. Quality installers source panels and inverters from authorised distributors with verifiable batch documentation. Key items:

Solar panels: Verify serial numbers and check manufacturer warranty card registration
Inverter: Confirm model matches approval; check anti-islanding certification (CEA 2019 compliant)
Mounting structure: Hot-dip galvanised steel (HDG) or aluminium; confirm gauge and wind load rating for your district (cyclone zones near Tamil Nadu coast require higher wind ratings)
DC cables: 4mm² or 6mm² twin-core DC solar cable (TUV rated, UV resistant)
AC cables, MCBs, SPDs, earthing materials

Stage 6: Installation Day

Typical duration: 1–3 days depending on system size

Morning: Mounting Structure Erection

The structural team installs rails and clamps on the roof. For RCC terraces, chemical anchors are drilled and resin-bonded into the slab — no welding on waterproofed surfaces. For Mangalore tile roofs, hook-mount systems preserve tile integrity.

Panel Placement and Cabling

Panels are placed into the mounting framework and secured. DC cables are run in conduit from the array to the inverter location (ideally shaded, well-ventilated, and within 10m of the DB). All DC connections are made using MC4 connectors — these must be properly seated and tested for continuity before energising.

Inverter Installation

The inverter is wall-mounted, typically indoors or under roof shade to prevent thermal derating. AC isolators, surge protection devices (SPDs on both DC and AC sides), and the main AC MCB are installed and wired into your DB.

Earthing

A dedicated earth electrode (copper-bonded rod or plate) is installed and bonded to the panel frame, inverter chassis, and your building's existing earth system. Earth resistance must measure below 5 ohms — we test this with an earth resistance tester before commissioning.

Stage 7: Testing and Commissioning

Typical duration: Half day

This stage is critical and should never be rushed.

IV Curve Testing

Using a solar analyser, each string's I-V (Current-Voltage) curve is traced and compared against the expected curve from panel datasheets. Deviations indicate mismatched panels, poor connections, or shading issues.

Insulation Resistance (IR) Testing

A 500V DC insulation resistance test is performed on all DC cables to confirm no insulation breakdown. Target: greater than 1 MΩ on any conductor-to-earth measurement.

Earthing Continuity

Continuity between all panel frames, inverter chassis, and earth electrode is verified. Earth resistance is measured and recorded.

Inverter Commissioning

The inverter is powered up, connected to the grid, and configured. Key settings: grid frequency limits (49.0–51.5 Hz as per CEA), voltage limits, anti-islanding protection, and monitoring connectivity (WiFi/LAN for data logging).

System Handover Documentation

You receive: commissioning report, test results, inverter manuals, warranty cards, panel serial numbers, and emergency shutdown procedure.

Stage 8: Net Meter Installation by TANGEDCO

Typical duration: 15–45 days after installation

Your installer submits the installation completion report with photographs to TANGEDCO. A TANGEDCO JE (Junior Engineer) visits to inspect and verify the installation. If satisfied, TANGEDCO replaces your existing single-direction meter with a bidirectional net energy meter that records both import (from grid) and export (to grid) separately.

What to do if there is a delay: Follow up at the subdivision office with your application acknowledgment number. Escalate to the Assistant Executive Engineer if no response after 30 days.

Stage 9: Subsidy Application (PM Surya Ghar Yojana)

Typical duration: 30–60 days for disbursal

Once the net meter commissioning certificate is in hand, your installer uploads it to pmsuryaghar.gov.in. The Central Financial Assistance is processed by MNRE and credited directly to your Aadhaar-linked bank account. No further action is required from your side — just verify the bank details are correct in the portal.

Stage 10: System Handover and Monitoring Setup

Typical duration: 1–2 hours on-site

Your installer configures the monitoring app on your smartphone — most modern inverters (Growatt, Solis, Huawei, SMA) have dedicated apps that show real-time generation, historical data, and fault alerts.

Walk through the system with your installer and confirm you understand:

How to read your net meter
The emergency DC isolator and AC isolator locations
What to do if the inverter shows a fault code
Scheduled maintenance requirements

Complete Timeline Summary

Stage	Duration
Site assessment and proposal	3–5 days
TANGEDCO feasibility application	7–30 days
Procurement	3–7 days
Installation	1–3 days
Testing and commissioning	1 day
TANGEDCO net meter installation	15–45 days
Subsidy disbursal	30–60 days
Total (first generation to subsidy in account)	60–150 days

The variability is almost entirely in the TANGEDCO and subsidy portal stages — not in the installation itself. An experienced installer manages these stages proactively and keeps you informed throughout.

Planning your solar installation in Tamil Nadu? Tristar Green Energy Solutions in Coimbatore manages every stage of this process — from the first energy audit through TANGEDCO coordination and subsidy disbursal. We have completed this process hundreds of times across Tamil Nadu and know exactly how to keep your project moving. Contact us for a free site assessment.

Solar Installation Process: What to Expect