Part of the complete guide: Solar for homes (start here)
Project snapshot
Independent villa, Trivandrum. Trivandrum.
| Property | Independent villa, Trivandrum |
|---|---|
| Loads | Centralised AC, 2 electric cars, normal household |
| Monthly bill before | ≈ ₹25,000 |
| Monthly bill after | ≈ ₹250 |
| System | ≈ 25 kW on-grid, three-phase |
| Approx. investment | ₹12–14 lakh |
| Payback | ≈ 4 years incl. petrol saved |
The problem
A large villa with centralised air-conditioning and two electric cars was paying about ₹25,000 every month. Two things drove the bill: round-the-clock AC and nightly EV charging at the highest slab rates.
What we designed
- A three-phase on-grid system sized to the villa's daytime and annual use rather than the roof's maximum.
- Layout around tree shade using a shade study.
- A dedicated EV charging circuit and an energy-monitoring app showing home, solar and EV load.
- Net-metering paperwork and grid approval handled with the installer.
The result
The monthly bill fell from about ₹25,000 to about ₹250, which is largely fixed charges. Fuel for the two cars also fell sharply because most charging is now covered by solar.
What other villa owners can learn
- Higher consumption means higher slab rates, so each unit solar covers is worth more.
- Size to your use; extra export earns much less than the retail units you avoid.
- Plan the EV charger and sanctioned-load upgrade at the same time.
Figures are rounded for readability. Results depend on roof, shade, tariff and usage.
