Rooftop solar for a housing society in Pune: what the committee actually decides

A Pune housing society has three practical options for its terrace: common-area solar, shared solar for the flats, or shared solar with a shared battery. Pune is supplied by MSEDCL (Mahavitaran), so the first two connect through MSEDCL net metering. The third never connects to the grid at all.

The options can be combined. Protostar designs the lifts, pumps and common lights into the roof plan from the first drawing, so one plant can serve the common meter and the flats. Our guide to solar for flats adds the two routes a single flat can take on its own.

Common-area solar is the simplest decision, but it does not reduce any flat's own electricity bill. It cuts the society's bill for lifts, water pumps, and staircase and compound lights, and residents feel the saving only through lower maintenance charges. Under ordinary net metering, credits earned on the common meter stay on the common bill and cannot be passed to individual flats.

Shared solar for flats puts the larger part of the roof to work for the homes. One plant is planned for the whole terrace, and a patented SPDU (Smart Power Distribution Unit) in the meter room gives each participating flat its own metered share. Think of your society's water tank: one tank on the roof, yet every home gets its own fair supply. Each flat sees its balance in the Nova app, like a prepaid recharge, and when its share is used up, its SPDU switches it to its own MSEDCL meter automatically.

Most committees find the real question is not common area against flats, but whether residents want backup. Shared grid-connected solar cuts bills and pauses in a power cut. Protostar Fusion adds a shared lithium battery bank, so the street goes dark and your homes don't. Our inverter and shared battery guide compares that backup with the inverters most flats already have.

For a Pune society, MSEDCL net metering works on one connection: the society's common meter. The plant sits behind that meter, and MSEDCL records what the plant exports and what the common connection imports. Under MERC's rooftop regulations, the plant is capped at the sanctioned load of the connection it sits on, which matters when one plant is meant to serve more than the common areas.

The paperwork has become simpler. Under MERC's Practice Direction of 30 June 2026, the agreement a consumer accepts while applying online counts as the net metering agreement, so MSEDCL cannot insist on a separate physical one. For Protostar's shared grid-connected solar, Protostar applies for net metering on the society's behalf.

Virtual net metering, which shares a plant's credits across flats' bills, is legal in Maharashtra, but MSEDCL is not approving applications, even after MERC penalised it in October 2025, so it is not an option for a Pune society today. Our guide to virtual net metering in Maharashtra explains where it stands. Fusion needs no net metering of any kind, because its plant never connects to the grid.

The terrace stays common property, and the society decides how it is used. MNRE's rooftop guidance puts solar at about 10 to 12 sq m of shadow-free roof per kW, and in a society building the water tanks, the lift room and their shade take part of every terrace. That is why splitting a terrace into a patch per flat rarely works, and why one plant planned for the whole roof usually serves every flat better.

Where the terrace suits it, Protostar can use a raised structure that uses the whole terrace and keeps it walkable. Your terrace stays yours. Fusion also needs space for the battery bank, in a ventilated battery room the society agrees to, and every option uses the meter room. Nothing inside any flat is rewired.

The general body needs to approve the use of the terrace, and for common-area solar, the spending of society funds. Most societies do this at an AGM or a special general body meeting, following their byelaws. Everything else is decided flat by flat. These are the steps a Pune committee usually goes through.

1. Collect the bills. Gather 12 months of electricity bills for the common meter and, from willing members, for their own flats.
2. Book a free rooftop survey. Protostar inspects the terrace, the meter room and the space for a battery room.
3. Compare the options in writing. The proposal costs common-area solar, shared grid-connected solar and Fusion side by side for your building.
4. Brief the committee, then the members. Protostar supports the committee with presentations, workings and documents for the meeting.
5. Pass the resolution. The general body approves the terrace use, and the society gives a no-objection certificate and right-of-use agreement for the roof, the meter room and any battery space.
6. Sign flat by flat. Each participating flat signs its own agreement and pays for its own share. Flats that do not join stay on their MSEDCL supply as before.
7. Install and switch on. A typical retrofit is completed in about 3 months, including approvals, with no work inside any flat.

Protostar maintains its shared plants under one annual maintenance contract for the whole building, covering panel cleaning, battery health in Fusion, performance monitoring and prompt issue resolution. Dust alone can cut generation by up to 25 percent, so regular cleaning is what protects the savings. The committee does not have to chase a vendor, and every flat sees its own solar balance and usage in the Nova app.

Protostar Fusion carries these warranties:

• Solar modules: 30-year performance warranty and 12-year product warranty.
• Hybrid inverter and mounting structure: 10 years.
• Fusion battery bank (LFP): 10-year warranty and a 20-year rated service life.
• Workmanship: 5 years.

Protostar's SPDUs have shared rooftop solar in Pune buildings since 2019 and have powered about 300 flats, all on grid-connected plants without batteries. Four of those buildings are listed below. Real roofs. Real bills. Real savings.

Scorpio is where the SPDU was invented. It was one of India's first net zero residential buildings, homebuyers paid no green premium, and it is now a Harvard Business Publishing case study (IM037B), written at IIM Bangalore in 2024. Read the Scorpio case study. At 7 Plumeria Drive, 9.6 kWh a day of solar per flat was measured, not modelled, and cross-checked within 2% against the independent site meter.