Solar for Apartments & Housing Societies | Tamil Nadu

Quick Answer: Tamil Nadu apartments can install solar on common terraces using group net metering. Credits are shared among flat owners proportionally. A 50kW system for a 50-flat apartment costs approximately ₹20-25 lakh, with each flat saving ₹800-1,500/month. Requires society committee resolution and TANGEDCO approval.

Apartment dwellers in Chennai, Coimbatore, Madurai, and other Tamil Nadu cities often assume that solar is only for independent houses. That assumption is wrong. Apartment complexes and housing societies can — and increasingly do — install rooftop solar, both for common area consumption and for individual flat owners. However, the process is more complex than a standalone home installation. It involves permissions from the residents' welfare association (RWA), decisions about cost sharing, TANGEDCO's group net metering rules, and coordination among multiple stakeholders. This guide walks through every step.

How Solar Works for Apartments in Tamil Nadu

Apartment solar installations fall into two distinct models:

Model 1: Common Area Solar

Solar panels installed on the terrace power the common area electricity connection — lifts, water pumps, stairway and parking lighting, CCTV systems, and common area air conditioning. The RWA or apartment association owns the system, and savings reduce the monthly maintenance charges for all residents.

• Typical size: 5–25 kW depending on common area consumption
• Grid connection: Net metered against the common area TANGEDCO meter
• Ownership: RWA or apartment management body
• Subsidy eligibility: Not directly eligible for PM Surya Ghar (which is for individual residential connections), but may qualify for state-level incentives

Model 2: Individual Flat Owner Solar (with Group Net Metering)

Individual flat owners install solar panels on the shared terrace, with each owner's allocated panels net-metered against their individual TANGEDCO connection. TNERC's regulations allow group net metering for multi-dwelling units where multiple consumers in the same building share rooftop space.

• Typical size per flat: 1–3 kW
• Grid connection: Each flat owner's panels are net-metered against their individual TANGEDCO meter
• Ownership: Individual flat owner
• Subsidy eligibility: Each flat owner can apply individually for PM Surya Ghar subsidy (up to ₹78,000)

Rooftop Rights and Permissions

The terrace of an apartment building is typically common area under Tamil Nadu's Apartment Ownership Act. No individual flat owner has exclusive rights to the terrace unless specified in the sale deed. This means:

1. For common area solar: The RWA/association can decide by majority resolution to install solar on common areas
2. For individual flat solar: The flat owner needs written permission from the RWA to use allocated terrace space
3. UDS (Undivided Share) consideration: Each flat owner's entitlement to terrace space is proportional to their UDS. A flat with 600 sq ft UDS in a 10,000 sq ft plot has 6% claim on common areas

Key Questions to Resolve Before Installation

• How much terrace area is available for solar? Deduct water tanks, lift rooms, overhead tanks, dish antennas, and mandatory walkways from total terrace area
• Is there shading from adjacent buildings? Tall neighbouring structures that shade the terrace between 9 AM and 4 PM reduce generation significantly
• Who maintains the system? Establish clear maintenance responsibilities before installation
• What happens when a flat is sold? Define whether the solar system transfers with the flat or must be removed

Society Resolution Process

For apartment associations and RWAs in Tamil Nadu, the decision to install solar requires formal approval:

Step 1: Proposal and Feasibility Study

The solar committee (or interested residents) commissions a feasibility study from a solar installer. This covers:

• Available terrace area and solar potential
• Expected generation and savings
• System cost and payment options
• Net metering process

Step 2: General Body Meeting

Present the proposal at a General Body Meeting (GBM). Under most apartment bylaws, a two-thirds majority of members present is required for capital expenditure decisions. Some societies require a simple majority.

What to present:

• Feasibility report with savings projections
• Cost per flat (if shared) or cost to association (if common area)
• Payback period calculation
• Proposed vendor and warranty terms
• Maintenance plan and responsibilities

Step 3: Formal Resolution

Pass a formal resolution authorising the installation. The resolution should specify:

• Total system capacity and cost
• Funding mechanism (association reserve fund, special assessment, or individual contribution)
• Vendor selection
• Authorised signatories for the TANGEDCO net metering application
• Maintenance responsibility assignment

Step 4: Collect Member Contributions (if applicable)

For individual flat-owner systems, each participating flat owner contributes their share. For common area systems, the association funds the installation from reserves or a special assessment.

Cost Sharing Models

For Common Area Solar

Model	How It Works	Best For
Association fund	Paid from the maintenance reserve corpus	Well-funded societies with adequate reserves
Special assessment	Equal or UDS-proportional one-time levy on all flat owners	Societies with limited reserves
Maintenance increase	Monthly maintenance increased to cover EMI (if loan-financed)	Societies preferring gradual cost absorption
Third-party OPEX	A solar company installs at zero cost; society pays per-unit rate lower than TANGEDCO	Societies wanting zero capex

For Individual Flat Owner Solar

Each participating flat owner bears their own system cost:

• Per flat cost (2 kW): ₹95,000–₹1,20,000
• PM Surya Ghar subsidy: ₹60,000 (for 2 kW)
• Net cost per flat: ₹35,000–₹60,000

Non-participating flat owners have no obligation to contribute — only those who opt in bear the cost.

Net Metering for Apartments: TANGEDCO Rules

Common Area Net Metering

• The RWA applies for net metering using the common area TANGEDCO consumer number
• The solar system is connected behind the common area meter
• Net metering works identically to a standalone connection — generation offsets common area consumption

Group Net Metering (Individual Flats)

TNERC regulations permit group net metering in apartment complexes:

• Multiple flat owners can install panels on a shared terrace
• Each owner's panel array is separately metered or allocated
• Generation is credited to each owner's individual TANGEDCO consumer number
• TANGEDCO installs bidirectional meters on each participating flat's connection

Technical requirement: The solar installer designs the system with separate MPPT (Maximum Power Point Tracking) channels or string configurations for each flat owner's panels, ensuring generation is attributable to each participant.

Application Process for Apartment Net Metering

1. RWA NOC: TANGEDCO requires a No Objection Certificate from the RWA authorising the rooftop solar installation
2. Individual Form NM: Each participating flat owner submits Form NM with their consumer number
3. Common SLD: A consolidated Single Line Diagram (SLD) showing all participants' panel arrays and connections
4. TANGEDCO inspection: A joint inspection of the entire installation (all participants' systems together)
5. Individual bidirectional meters: TANGEDCO installs separate net meters for each participant

Timeline: Group net metering applications typically take longer than standalone applications — expect 60–120 days from application to meter installation due to the complexity of multi-consumer processing.

PM Surya Ghar for Individual Flat Owners

Individual flat owners in apartments are eligible for PM Surya Ghar subsidy, provided:

• They have an individual domestic TANGEDCO connection (not shared metering)
• The system is net-metered against their individual consumer number
• They use a nationally empanelled vendor
• They have RWA permission for rooftop access

Each eligible flat owner can receive up to ₹78,000 subsidy independently. In a 20-flat apartment where 15 owners install 2 kW each, the total subsidy drawn is 15 x ₹60,000 = ₹9,00,000 — a significant incentive that makes apartment solar highly attractive.

Case Study Examples

Case 1: 40-Flat Apartment Complex in Chennai — Common Area Solar

• Common area consumption: 4,000 units/month (3 lifts, 2 water pumps, common area lighting, CCTV)
• System installed: 20 kW rooftop solar
• Monthly generation: 2,400 kWh
• Monthly savings: ₹16,800 (at commercial tariff ₹7/unit)
• System cost: ₹9,60,000
• Cost per flat: ₹24,000 (one-time special assessment)
• Payback per flat: 17 months
• Monthly maintenance reduction per flat: ₹420/month after payback

Case 2: 12-Flat Villa Community in Coimbatore — Individual Group Net Metering

• Participating flats: 8 out of 12
• System per flat: 2 kW
• Total installation: 16 kW
• Cost per flat (before subsidy): ₹1,05,000
• PM Surya Ghar subsidy per flat: ₹60,000
• Net cost per flat: ₹45,000
• Monthly generation per flat: 240 kWh
• Monthly EB bill reduction: ₹800–₹1,200
• Payback per flat: 3–4 years

Case 3: Gated Community in Madurai — Hybrid Approach

• Common area: 25 kW solar for pumps, lighting, and clubhouse
• Individual: 30 homeowners installed 3 kW each (90 kW total)
• Total community solar: 115 kW
• Annual community savings: ₹18,00,000+
• Result: Monthly maintenance reduced by ₹1,200 per home; individual bills reduced by 60–80%

Common Area Solar: What to Power

Common Area Load	Typical Power	Monthly Consumption	Solar Potential
Lifts (2 nos)	7.5 kW each	1,500–2,000 kWh	Partially (lift runs intermittently)
Water pumps (2 nos)	2 HP each	800–1,200 kWh	Fully coverable
Common area lighting	2–5 kW	300–600 kWh	Fully coverable
CCTV and security	0.5–1 kW	360–720 kWh	Fully coverable
Clubhouse AC	5–10 kW	1,000–2,500 kWh	Partially (daytime only)

A 10–25 kW system typically covers 50–80% of common area consumption, depending on the load profile.

Challenges and How to Address Them

Ownership Disputes

Challenge: Who owns the solar panels if they are on common area? Solution: The society resolution should clearly state ownership — for common area systems, the association owns the asset. For individual systems, each flat owner owns their panels. Document this in writing.

Maintenance Responsibility

Challenge: Who cleans the panels? Who handles repairs? Solution: Include an Annual Maintenance Contract (AMC) in the installation agreement. For common area systems, the AMC cost is part of maintenance charges. For individual systems, each owner is responsible (or collectively hire an AMC provider).

Terrace Access and Safety

Challenge: Residents accessing the terrace may damage panels or wiring. Solution: Install protective fencing around panel arrays, ensure cable management is concealed, and display safety signage. Include terrace access rules in the society bylaws.

Non-Participating Owners' Concerns

Challenge: Owners who do not want solar may object to terrace area being used. Solution: Ensure the resolution process follows the society bylaws. Common area solar benefits all residents through reduced maintenance. Individual solar uses proportional terrace allocation and does not disadvantage non-participants.

Billing Complexity

Challenge: Tracking net metering credits for multiple flat owners. Solution: TANGEDCO's bidirectional meters handle this automatically for each participating connection. Request smart meters for automated reading and transparent tracking.

Step-by-Step Implementation Guide

1. Gauge interest: Conduct an informal survey among residents to identify interest level
2. Form a solar committee: 3–5 interested residents to drive the project
3. Commission a feasibility study: Engage a professional solar installer to assess the terrace, shading, and consumption patterns
4. Decide on the model: Common area, individual, or hybrid
5. Present to General Body: Share feasibility findings, costs, and expected savings
6. Pass resolution: Formal approval with specified terms
7. Select vendor: Compare at least 3 empanelled installers on price, quality, and after-sales support
8. Apply for PM Surya Ghar (individual participants) and TANGEDCO net metering (all participants)
9. Installation: Coordinate with the vendor for terrace access and installation schedule
10. Inspection and commissioning: TANGEDCO inspection, meter installation, and system activation
11. Set up monitoring: Ensure all participants can track their generation and savings
12. Establish maintenance protocol: AMC, cleaning schedule, and point of contact for issues

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Tristar Green Energy Solutions has completed solar installations for multiple apartment complexes and housing societies across Tamil Nadu. We handle the complete process — from the initial feasibility study and society presentation to TANGEDCO group net metering coordination and PM Surya Ghar subsidy assistance for individual flat owners. Contact us to schedule a free feasibility assessment for your apartment complex.