Solar Cost Calculator

How the estimate works

One kilowatt of solar panels in a sunny climate typically generates around 4 units (kWh) per day — roughly 120 per month. Dividing your monthly consumption by that figure gives the system size; multiplying the size by the installed price per kW gives the cost. Savings assume solar offsets your billed units at your current tariff, and the payback period is simply cost divided by yearly savings.

Make it accurate for your city

All four inputs are editable for a reason: tariffs differ by slab and utility, installation prices change with panel and battery markets, and sunshine varies by region. Take the per-kW cost from two or three local installer quotes, and your per-unit rate from the last bill (total amount ÷ units gives your true blended rate including taxes). Note this estimate excludes batteries — backup storage adds significant cost — and net metering can improve the payback further by selling surplus units back to the grid.

Formula used

How to use this tool

1. 1Enter your monthly electricity units and per-unit rate.
2. 2Adjust generation and cost-per-kW for your area.
3. 3Optionally add a battery cost.
4. 4Tap Calculate for size, cost and payback.