Rooftop solar turns your roof into a small power plant that offsets your electricity bill for 25 years. Here's how to size it, what it costs, and how to judge the payback — without any brand pitch.
How much power does 1 kW give?
In most of India, 1 kW of solar generates roughly 4–5 units (kWh) per day on average across the year — call it ~1,400–1,600 units annually — depending on your location, shading and panel orientation. Sunnier states sit at the higher end.
Sizing your system
Work backwards from your consumption:
- Look at your monthly bill for units consumed.
- Divide by 30 for daily units.
- Divide by ~4 (units per kW per day) to estimate the kW you need.
For example, ~400 units/month ≈ ~13 units/day ≈ a ~3 kW system. Roughly, plan for about ~90–100 sq ft of shade-free roof per kW.
What it costs
Installed cost varies by system type, quality and location, but a useful planning range for a grid-tied home system is on the order of ₹45,000–₹70,000 per kW before subsidy. Costs per kW fall as system size grows. Higher-efficiency panels and hybrid systems (with battery) cost more.
Payback — the honest version
Payback depends on three things: your tariff (higher slabs = faster payback), any subsidy, and your generation. For a typical grid-tied home offsetting expensive upper-slab units, simple payback commonly lands around 4–6 years, after which the electricity is essentially free for the panels' remaining life (warranties often run ~25 years).
The higher your current per-unit tariff, the more each solar unit saves — so high-bill households get the fastest payback.
Grid-tied and net metering
Most homes install grid-tied (on-grid) solar with net metering: you consume solar directly, export the surplus to the grid, and your DISCOM credits those units against what you draw at night. You apply for net metering through your electricity distribution company. (See our separate guides on net metering and on-grid vs off-grid.)
Before you commit
- Check your roof's shade through the day and its structural condition.
- Confirm net-metering availability and limits with your DISCOM.
- Insist on BIS-standard equipment and a proper warranty.
- Match system size to consumption — oversizing without net metering wastes generation.
Solar is one of the few home upgrades that pays you back and then keeps paying. If the upfront cost is the barrier, it can be financed and repaid partly from the bill savings — which is exactly the kind of clean-energy financing IndiaCard helps arrange through regulated lenders.