Rooftop solar for apartments and gated communities in Chennai

Two ways solar works in an apartment

An apartment terrace is shared, so rooftop solar in a block of flats is planned differently from an independent house. There are two common set-ups, and many communities use both.

1. A common-area system for the association

The residents' welfare association (RWA) or owners' association installs one system on the terrace and connects it to the common-services electricity connection. This is the connection that runs the lifts, water pumps, corridor and staircase lights, parking and street lights, the gate, the sewage treatment plant and shared EV chargers. Solar cuts this bill, which lowers the maintenance charges every flat pays.

2. A system for an individual flat

A flat owner installs a small system on a part of the terrace allotted to them and connects it to their own electricity connection. This needs the association's written permission, a fair way of sharing terrace space, and a safe cable route from the terrace down to the flat's meter.

Why common areas suit solar so well

• Daytime loads: pumps, lifts, the sewage treatment plant and security systems run during the day, when panels produce the most.
• A separate tariff: common services are billed on their own tariff category in Tamil Nadu, not on the slab tariff of individual homes, so the association can see clearly how many units solar replaces.
• One decision, shared benefit: the association decides once, and the savings reach every flat through lower common-area bills.

PM Surya Ghar support for associations and flat owners

Under the central government's PM Surya Ghar: Muft Bijli Yojana, residential associations and individual flat owners can both get central financial assistance, at different rates.

Example only: a 40-flat association that installs a 20 kW system for its common areas would be eligible for 20 × ₹18,000 = ₹3,60,000 of central support. Its limit is 40 × 3 = 120 kW, so 20 kW is well within it.

The subsidy is paid only for grid-connected systems that use made-in-India panels and are applied for through the PM Surya Ghar portal before installation. There is currently no separate Tamil Nadu subsidy on top. Read the full PM Surya Ghar subsidy guide for eligibility, documents and timelines.

Net metering for the common-services connection

The Tamil Nadu Electricity Regulatory Commission (TNERC) has said that net metering applies to all domestic categories, including the common-services connection used by apartments. With a net meter, solar units used on site reduce the bill directly, and surplus units sent to the grid are set off against units drawn later.

• The system size is limited by the sanctioned load of the connection it is attached to.
• TNPDCL checks the capacity of the local transformer before approving the connection.
• A grid-connected system switches off during power cuts. If your pumps or lifts must run during cuts, ask us about a hybrid system with batteries for selected loads.

We confirm the current TNPDCL procedure for your connection before you apply. See net metering in Tamil Nadu for the step-by-step process.

Terrace space, structure and waterproofing

Plan for about 100 square feet of shade-free terrace per kW. On an apartment roof, the usable area is often reduced by:

• overhead water tanks, lift machine rooms and staircase heads, and the shadows they cast
• taller neighbouring buildings, telecom towers and trees
• space residents use for drying clothes, gatherings or terrace gardens

An elevated structure lifts the panels above head height, so the terrace stays usable underneath and gets shade as a bonus. You can see one in our featured project. On apartment terraces we plan the fixing method so the waterproofing is protected, keep walkways clear for cleaning and maintenance, and design the structure for Chennai's cyclone-season winds.

For new buildings, a 2021 CMDA notice asked owners in Chennai to reserve one-third of the terrace area for solar panels. If your building was approved with space set aside, that area is the natural place to start.

Steps for an RWA or association

1. Collect the bills. Gather the last 12 months of common-services electricity bills and note the sanctioned load.
2. Free site visit. Our engineer surveys the terrace, checks shading and the electrical room, and suggests a system size.
3. Fixed itemised quote. You get a written quote listing panels, inverter, structure, cabling, safety equipment and paperwork, which is easy to share with the committee.
4. Association approval. The committee or general body approves the project as your by-laws require, and records a resolution.
5. Applications. We handle the PM Surya Ghar application in the association's name and the TNPDCL net-metering paperwork.
6. Installation and inspection. We install the system, TNPDCL inspects it and fits the net meter, and the system is switched on.
7. Subsidy and upkeep. The subsidy is claimed after commissioning, and a cleaning and maintenance schedule keeps output high.

Building a new apartment or villa community?

Solar is easiest and neatest when it is planned before construction: conduits laid inside the walls, a structure designed with the terrace, and space kept free of tanks and machine rooms. Our group company, VM Skyline Constructions, designs and builds houses and villas, so we can plan solar into the design from day one. Read more about solar for new homes and villas.

Frequently asked questions