Solar Rooftop Calculator India

Solar Rooftop Calculator India: Check Your Exact ROI & Subsidy (2026)

We built this Solar Rooftop Calculator India to give you an honest, mathematical answer. No sales pitch, just data. Whether you are planning for a small 3kW system for your home or a larger setup, this tool accounts for the latest PM Surya Ghar Muft Bijli Yojana subsidies, rising tariff rates, and even loan interest if you are financing the project.

Let us help you find the exact date your electricity becomes free.

What is a Solar Rooftop Payback Calculator?

A solar payback calculator is a digital tool designed to tell you how much time it will take to recover the money you spent on installing solar panels. This period is called the “break-even point.”

Think of it this way. If you spend ₹1,00,000 on a system and it saves you ₹25,000 every year in electricity bills, your payback period is 4 years. After year 4, every unit of electricity generated is essentially 100% profit for you.

Unlike generic calculators you might find on international sites, this specific tool is tailored for the Indian market. It includes:

• Indian currency (INR) inputs.
• Current 2026 central government subsidy structures.
• Average Indian solar generation data (specific to our latitude).

How This Calculator Works

Understanding the math behind the tool helps you trust the results. Here is a breakdown of the logic we use to generate your report.

1. System Sizing

The tool first determines how big a solar plant you need. It does this in two ways. You can either tell us the kW capacity you want, or you can simply enter your monthly electricity bill. If you enter the bill amount, we divide it by your per-unit rate to find your consumption and recommend a system size that covers your needs.

2. Cost Estimation

We use a market average of ₹50,000 to ₹60,000 per kW. This covers the cost of monocrystalline panels, inverters, mounting structures, and installation charges. You can edit this field if you have a specific quote from a vendor.

3. Subsidy Deduction

This is the most critical part. The government of India offers significant financial aid under the PM Surya Ghar scheme.

• For systems up to 2kW, you get ₹30,000 per kW.
• For the additional capacity between 2kW and 3kW, you get ₹18,000 per kW.
• The subsidy is capped at ₹78,000 for systems above 3kW.

Our calculator automatically subtracts this amount from your total cost to show you the “Net Investment.”

4. Savings Calculation

We assume a conservative generation average of 120 units (kWh) per kW per month. By multiplying this by your local electricity tariff, we find your monthly savings.

How to Use the Solar Rooftop Payback Calculator – Step-by-Step Guide

Follow these simple steps to get your accurate ROI report.

Step 1: Choose Your Mode At the top of the calculator, you will see two tabs.

• By System Size: Select this if you already know you want a 3kW or 5kW system.
• By Monthly Bill: Select this if you are unsure. Enter your average bill amount (e.g., ₹3,500), and we will calculate the size for you.

Step 2: Enter Your Costs (Optional) The “System Cost per kW” is pre-filled with the market average. If you have received a quotation from a local EPC installer, enter that specific rate here for better accuracy.

Step 3: Check Electricity Rate Look at your latest bill from your DISCOM (electricity board). Enter the cost of one unit of power. In most Indian metros, this is between ₹7 and ₹9.

Step 4: Financing Check Are you taking a solar loan? Click the “Financing this system?” checkbox. Enter the interest rate (usually 9% to 11% for green loans) and the tenure. The calculator will tell you your monthly EMI.

Step 5: Click Calculate Hit the button and scroll down to see your detailed invoice-style report.

Example Calculation

To help you understand what the results mean, let us look at a real-world example of a typical middle-class Indian household.

Scenario: Mr. Sharma in Delhi has a monthly bill of ₹3,000. He wants to go solar.

The Result:

• Govt Subsidy: ₹78,000 is deducted immediately.
• Net Cost to Mr. Sharma: ₹87,000.
• Monthly Savings: ₹2,880.
• Payback Period: Approximately 2 Years and 6 Months.

This means Mr. Sharma recovers his ₹87,000 in just 2.5 years. Since solar panels have a performance warranty of 25 years, he enjoys free electricity for the next 22.5 years.

Key Benefits of Using This Calculator

Why should you rely on this tool instead of a rough guess?

• Inflation Adjustment: Under “Advanced Settings,” you can add electricity inflation. Grid tariffs rise by about 5% every year. This tool shows you how much you save in the future, not just today.
• Loan Clarity: Most people forget to account for interest when calculating ROI. Our tool deducts your EMI interest to show you the real net profit.
• Environmental Impact: It motivates you by showing exactly how many tonnes of Carbon Dioxide (CO2) you are offsetting and how many equivalent trees you have planted.
• Instant Planning: You do not need to wait for a vendor site visit to know if your budget allows for solar. You get a clear financial picture in seconds.

Who Should Use This Calculator?

• Homeowners: Calculate savings for your independent house or villa.
• Housing Societies: RWAs can estimate savings for common area lighting and elevators.
• Students & Researchers: Useful for understanding the economics of renewable energy projects.
• Financial Planners: Help clients decide if a solar rooftop system is a good investment compared to Fixed Deposits or Mutual Funds.

Common Mistakes to Avoid While Using the Calculator

To ensure your results match reality, avoid these common errors.

1. Ignoring Shadow Free Area The calculator assumes your roof gets direct sunlight. If your roof has shade from nearby buildings or water tanks, your generation will be lower. In such cases, consider using half-cut cell technology or micro-inverters.

2. Entering Winter Bill Only Do not just use your January bill. Your AC usage in summer is higher. Always take an average of the last 12 months for the “Monthly Bill” input to get the correct system size.

3. Overestimating Unit Rates Some users enter the highest slab rate. While you do save on the highest slab, fixed charges on your bill (meter rent, etc.) still apply. Use the average cost per unit.

4. Forgetting Maintenance While solar is low maintenance, you still need to clean the panels every two weeks. If you hire a cleaning service, that is a small recurring cost to keep in mind.

Why Online Solar Calculators are Better Than Manual Calculation

Trying to do this in Excel or on paper is difficult because the subsidy slabs are complex.

The PM Surya Ghar scheme has different rates for the first 2kW and the rest. Calculating this manually leaves room for error. An online calculator has the logic coded in, so you never miss a subsidy slab or a leap year in your ROI calculation. It is faster, error-free, and handles complex variables like compound inflation instantly.

Frequently Asked Questions (FAQ)

Is the PM Surya Ghar subsidy guaranteed for everyone?

The subsidy is available for residential consumers with a valid electricity connection. However, the installation must be done through a registered vendor, and the technical feasibility must be approved by your local DISCOM.

Does this calculator account for Net Metering?

Yes, the logic assumes a net metering arrangement where you export excess power to the grid during the day and import it at night, effectively banking your units.

What happens if my roof has shade?

If your roof has partial shade, the Monthly Savings shown by the calculator will be lower in reality. You should consider using bifacial panels or optimizing the placement to mitigate shade issues.

Can I use this calculator for commercial connections?

This specific calculator is optimized for residential subsidies. Commercial entities do not get the PM Surya Ghar subsidy but can claim accelerated depreciation benefits, which requires a different calculation.

How accurate is the ROI calculation?

The calculation is highly accurate for financial planning. However, real-world generation depends on weather conditions, the tilt angle of your panels, and regular cleaning of the modules.

Does the calculator include battery costs?

No, this is for an On-Grid system (without batteries), which provides the highest ROI. Hybrid solar systems with batteries cost significantly more and have a longer payback period because batteries need replacement every 5 to 7 years.

What is the average solar panel price in India in 2026?

Prices have stabilized between ₹50,000 to ₹60,000 per kW for a complete setup (including structure, wiring, and installation). Premium brands like Tata Power or Adani Solar may charge slightly more.

Why does the calculator ask for inflation?

Electricity from the grid gets expensive every year. By inputting inflation, you see the future value of your savings, which helps you understand why locking in your energy cost today is a smart move.

Final Thoughts

Switching to solar is one of the safest financial decisions you can make in 2026. It is one of the few investments that offers a guaranteed return of over 20%, tax-free (in the form of savings).

Use the calculator above, play around with the numbers, and see how a solar loan might actually be cheaper than your current electricity bill. Once you are confident in the numbers, the next step is to call a trusted local installer for a site survey.

Stop renting your electricity. Start owning it.