SOLAR CALCULATOR
Rooftop solar cost and savings calculator
Explore your rooftop’s potential, estimated savings and indicative installation costs.
Tell us about your property
Use figures for the same month. Monthly units take priority; if left blank, consumption is estimated from bill ÷ tariff. Any field can be cleared and retyped.
Assumptions & calculation method
Capacity uses 500 Wp panels, 10 sq m of usable roof per kWp and your monthly consumption. The selected roof percentage is applied once. Panel count rounds up to meet demand, then is capped by roof space. Final design may use different modules.
Generation assumes 4.5 peak sun hours/day and an 80% performance ratio (20% combined system losses): 1,314 kWh/kWp in year one. These are planning assumptions, not a measured forecast for your address. Annual generation is divided by 12 for monthly averages and 365 for daily averages; actual seasons vary. Output falls by 0.5% annually in the 30-year projection.
On-grid savings assume 60% of generated energy is used directly, capped by monthly consumption and the entered bill. Export credit is ₹0 until the applicable arrangement is confirmed. Fixed and demand charges remain payable. No subsidy is deducted automatically.
Simple payback = system cost ÷ year-one savings. Annual ROI here means year-one bill savings ÷ cost, not investment IRR. Savings are gross: maintenance, finance, inverter replacements and other running costs are excluded. Tariffs and consumption stay constant; the 30-year total is not net profit or a performance guarantee.
Pricing is proportional below 3 kW, interpolated between 3, 5 and 10 kW, and requires a custom quote above 10 kW. Battery scenarios include an illustrative ₹18,000 per nominal kWh plus conversion/control allowances of ₹12,000/kW off-grid or ₹18,000/kW hybrid. These are budget assumptions, not supplier quotations.
Environmental estimates use an illustrative constant 0.70 kg CO₂/kWh, assuming generated energy displaces grid electricity. This is not a carbon-credit or lifecycle assessment; future grid changes and manufacturing emissions are excluded. Tree equivalents use the EPA’s 0.060 tonnes per seedling grown for 10 years, an educational comparison rather than a local planting claim.
RECOMMENDED PLANT SIZE
Sized for your electricity consumption · 10 assumed 500 Wp panels
Electricity generation
Electricity bill savings at ₹8/unit
On-grid, direct-use savings: 60% assumed self-consumption; no export credit. Gross savings before running costs.
Estimated project cost · on-grid
- Estimated system cost
- ₹3,50,000
Considering battery backup?
Each scenario allows 5 kWh nominal battery capacity, 4.0 kWh usable at 80% depth of discharge and approximately 3.6 kWh delivered after a further 10% conversion loss. This is a storage allowance, not a whole-home backup promise.
Costs include a battery allowance of ₹90,000. Allow a similar battery replacement budget around years 10 and 20 for planning; actual life varies. Savings and payback above are on-grid only. Storage losses, load timing and replacements require a separate off-grid/hybrid assessment.