Slashing the Society Maintenance Bill
For Cooperative Housing Societies (CHS) in Mumbai, the electricity bill for common areas—powering heavy-duty water pumps, multiple high-speed elevators, and corridor lighting—is often the largest single expense. Transitioning to a rooftop solar power system can virtually eliminate this cost. However, unlike individual homeowners, a housing society must navigate a more complex set of bureaucratic approvals with Tata Power to secure a bulk Net Metering agreement.
Key Requirements for Society Solar
- General Body Resolution (AGM/SGM): Tata Power requires a formal resolution passed by the society members authorizing the solar project and the capital expenditure. The resolution must be signed by the Chairman and Secretary.
- Roof Rights and Structural Stability: The society must provide a structural stability certificate from a BMC-approved structural engineer proving the roof can bear the wind-load and dead-weight of the solar panels and mounting structures.
- Unified Single Meter: Solar net metering is usually applied against the main common area meter. If the society has multiple smaller meters for different pumps or wings, it is highly recommended to consolidate them into one single high-capacity meter before applying for solar, ensuring maximum offset of units.
The Tata Power Net Metering Process
The process demands exact technical coordination between the solar EPC vendor and Tata Power.
- Submission of SLD: The solar vendor submits a Single Line Diagram (SLD) of the proposed solar plant to Tata Power for technical feasibility clearance.
- CEIG Approval: Since society solar plants are often large (ranging from 20kW to 100kW), a safety certificate from the Chief Electrical Inspector to Government (CEIG) is mandatory before commissioning.
- Installation and Synchronization: Once panels are mounted and inverters are wired to the main panel, Tata Power conducts an anti-islanding test. This ensures the solar plant instantly shuts off during a grid power cut, protecting linemen from backfeed electrocution.
- Bi-Directional Meter Installation: Finally, Tata Power replaces the old common meter with a digital bidirectional net meter, and a formal Net Metering Agreement is signed between the society and the utility.
Frequently Asked Questions
Can solar panels power the elevators during a power cut?
No. A standard grid-tied solar system with net metering shuts down automatically during a power cut for safety reasons. To run lifts during an outage, the society still needs a diesel generator or a massive battery backup system.
Are housing societies eligible for government subsidies?
Yes. Under the PM Surya Ghar scheme, Group Housing Societies (GHS) and RWAs can avail subsidies for common facilities, subject to specific kW caps.
What happens if the solar plant generates more than we use?
Excess units are exported to the grid and carried forward as credits to the next billing cycle. At the end of the financial year, Tata Power compensates the society for any net surplus at an agreed pooling rate.
Do we need BMC permission to install solar panels on the roof?
Generally, if the installation is within the existing parapet height and doesn’t alter the building’s FSI, explicit BMC permission is not required, but a structural stability certificate is mandatory.
How long is the payback period for a society?
Given the high commercial tariffs applied to society common meters in Mumbai, the ROI is excellent, usually paying for itself within 3 to 4 years.