Solar Payback Calculator

How This Solar Payback Calculator Works

Pick your solar system capacity and this calculator auto-fills the estimated system cost, the government subsidy and the expected electricity generation for you, using a single, editable reference table -- so you only need to type in the genuinely personal details: your electricity tariff and current monthly bill. It then compares your net installation cost -- the estimated system price minus the subsidy -- against the money you're expected to save on electricity bills every year, minus what you spend on maintenance. The payback period is how long it takes for those accumulated savings to equal what you paid upfront. Two payback figures are shown: a simple year-one estimate, and a more detailed year-by-year figure that accounts for electricity prices rising over time and panel output gradually declining. If you have an actual installer quotation, switch any "Auto" field to "Customize" and enter your own numbers -- the calculation logic is exactly the same either way.

Where the Government Subsidy Estimate Comes From

The auto-filled subsidy uses the Central Financial Assistance (CFA) structure of the PM Surya Ghar: Muft Bijli Yojana scheme for residential rooftop solar, as published in the Ministry of New and Renewable Energy's operational guidelines: ₹30,000 per kW for the first 2 kW, ₹18,000 per kW for the next 1 kW (2-3 kW), capped at a maximum of ₹78,000 per household -- with no additional central subsidy for capacity beyond 3 kW, which is why a 5 kW and a 10 kW system both show the same subsidy amount as a 3 kW system. Special category states and UTs (Uttarakhand, Himachal Pradesh, Jammu & Kashmir, Ladakh, the North-Eastern states and island territories) get a higher rate, capped at ₹85,800. This is the central government's contribution only -- several states run their own additional top-up subsidies, which vary too much to standardise here, so always confirm current eligibility, empanelled-installer requirements and the exact disbursement process on your DISCOM's or state renewable energy agency's official portal before making a decision. Treat every subsidy figure on this page as an estimate, subject to eligibility -- not a guaranteed amount.

Where the System Cost and Generation Estimates Come From

The auto-filled system cost uses a typical per-kW installed cost that declines as capacity increases (fixed costs like inverters and wiring are spread over more panels), based on commonly-quoted industry ranges -- roughly ₹65,000-75,000/kW for small 1-3 kW systems, declining to roughly ₹43,000-48,000/kW for larger 10-20 kW systems. Actual quotes vary by installer, panel brand, roof type and city, so this is only a starting estimate -- switch to "Customize" and enter your own quotation whenever you have one. Expected generation assumes roughly 4 units (kWh) of electricity per kW of capacity per day (≈120 units/kW/month) on average across the year, a widely-used rule of thumb for India -- actual generation depends on your location's sunlight hours, roof orientation, shading and the season (typically higher in summer, lower during the monsoon).

Why Electricity Price Inflation and Panel Degradation Matter

A solar system doesn't save you the same rupee amount every year. As grid electricity tariffs rise over time (the "Electricity Price Inflation" assumption), the same units of solar generation offset a bigger bill, so your savings tend to grow year on year. At the same time, panels lose a small amount of output efficiency every year (the "Annual Panel Degradation" assumption, typically well under 1% annually for good-quality panels) -- so slightly less electricity is generated as the system ages. This calculator models both effects together for the year-by-year payback and lifetime totals, while the "Simple Payback" figure deliberately ignores them for a quick, easy-to-eyeball comparison against your installer's quote.

Understanding Lifetime Savings and ROI

Lifetime savings is your total net profit from the system over its entire expected life -- all the accumulated bill savings, minus all the maintenance costs, minus the net installation cost you paid upfront. ROI (return on investment) expresses that lifetime savings as a percentage of what you invested, so you can compare it against other uses of the same money. The annualised ROI figure divides that total return evenly across the system's life as a simple, easy-to-understand estimate -- it is not a compounded annual growth rate (which would require modelling exactly when each rupee of savings arrives and could be reinvested), so treat it as a rough yearly average rather than a precise investment return metric.

What This Calculator Doesn't Account For

This is an educational planning tool, not a substitute for a professional site survey or your installer's detailed quote. It doesn't model net-metering export credits, batteries or backup systems, state-specific top-up subsidies, changes in your own electricity consumption over time, financing costs if you take a loan for the system, tax incentives beyond the subsidy you enter, or unusual weather/shading effects on generation. All "Auto" figures -- system cost, subsidy and expected savings -- are estimates that can and do vary by installer, location and eligibility; the payback period and every other result shown here should be treated as an estimate, not a guaranteed outcome. Actual results depend heavily on your roof's orientation, local sunlight hours, the quality of the installation, your real consumption pattern and how electricity tariffs actually move in your area over the years -- all of which you should discuss with a qualified solar installer, and verify against the official PM Surya Ghar portal, before making a decision.

Is my data sent to any server?

No. Every number you enter and every result shown is calculated directly in your browser using JavaScript. Nothing you type into this calculator is ever transmitted to OurPaisa Tools' servers or stored anywhere -- close the tab and it's gone.

Disclaimer: This tool provides an estimate for general informational purposes only and does not constitute financial or investment advice. The calculator is an educational planning tool and results -- including the auto-estimated government subsidy, system cost and generation figures -- are estimates based on the assumptions built into or entered on this page, and are subject to eligibility, location and change. Actual solar generation, savings, maintenance costs, subsidy eligibility and system life vary based on your location, installation quality, electricity tariffs and other factors. See our Disclaimer and Terms of Use for more detail.