Muthoot Finance Interest Rate Calculator

Solar Panel ROI & Savings Calculator

Investment Analysis

Net System Cost:

Payback Period:

Year 1 Savings:

25-Year Total Profit:

function calculateSolarROI() { var size = parseFloat(document.getElementById('systemSize').value); var cost = parseFloat(document.getElementById('totalCost').value); var rate = parseFloat(document.getElementById('elecRate').value); var sun = parseFloat(document.getElementById('sunHours').value); var credit = parseFloat(document.getElementById('taxCredit').value); var degradation = parseFloat(document.getElementById('degradation').value) / 100; if (isNaN(size) || isNaN(cost) || isNaN(rate) || isNaN(sun)) { alert("Please enter valid numbers in all fields."); return; } var netCost = cost * (1 – (credit / 100)); // Annual production = size * daily sun hours * 365 * 0.78 (standard derate factor for inverter/wire loss) var annualKWh = size * sun * 365 * 0.78; var year1Savings = annualKWh * rate; var totalSavings25Years = 0; var currentYearSavings = year1Savings; for (var i = 0; i < 25; i++) { totalSavings25Years += currentYearSavings; currentYearSavings *= (1 – degradation); } var paybackYears = netCost / year1Savings; var totalProfit = totalSavings25Years – netCost; document.getElementById('netCostDisplay').innerText = "$" + netCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('paybackDisplay').innerText = paybackYears.toFixed(1) + " Years"; document.getElementById('year1SavingsDisplay').innerText = "$" + year1Savings.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('totalProfitDisplay').innerText = "$" + totalProfit.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('resultsArea').style.display = 'block'; }

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Understanding Your Solar Return on Investment (ROI)

Switching to solar energy is one of the most significant financial decisions a homeowner can make. Beyond the environmental benefits, solar panels act as a hedge against rising utility costs. To determine if solar is right for you, you must understand the key metrics that drive your Return on Investment.

Key Factors in Solar Calculations

• System Size: Usually measured in kilowatts (kW). A typical residential system ranges from 5kW to 10kW.
• Solar Irradiance: This is represented by "Peak Sun Hours." It isn't just how long the sun is up, but the intensity of the light available to produce power in your specific geographic location.
• Federal Tax Credit (ITC): As of 2024, the federal government offers a 30% tax credit on the total cost of solar installation, significantly reducing the "Net Cost."
• Degradation Rate: Solar panels lose a tiny bit of efficiency every year (usually 0.5%). High-quality panels maintain higher output over a 25-year lifespan.

How to Use This Calculator

To get an accurate estimate, look at your most recent electricity bill to find your "Rate per kWh." Then, estimate your system size based on your roof space or quotes from installers. The calculator accounts for system inefficiencies (derate factor) and annual degradation to give you a realistic view of 25-year earnings.

Example Scenario

If you install a 7kW system at a cost of $21,000 in an area with 5 sun hours per day and electricity costs $0.18/kWh:

1. Gross Cost: $21,000
2. 30% Tax Credit: -$6,300
3. Net Investment: $14,700
4. Annual Production: ~10,000 kWh
5. Annual Savings: ~$1,800
6. Payback Period: Approximately 8.1 years

After the payback period, the electricity generated by your system is essentially free, leading to tens of thousands of dollars in pure profit over the remaining life of the panels.