Mortgage Calculator by Payment

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Solar Panel ROI Calculator

Estimate your payback period and lifetime savings from solar energy.

Net System Cost:
Estimated Annual Production:
Year 1 Savings:
Payback Period:
25-Year Total Net Profit:

Understanding Solar Panel Return on Investment (ROI)

Switching to solar energy is one of the most significant financial investments a homeowner can make. Calculating the Return on Investment (ROI) involves more than just looking at the initial price tag; it requires analyzing energy production, utility rates, and government incentives.

How This Calculation Works

To determine your solar ROI, we use several key metrics:

  • Net Cost: The gross cost of installation minus the Federal Investment Tax Credit (ITC) and local rebates.
  • Production Efficiency: We assume a standard 78% system efficiency factor, accounting for energy loss in inverters and wiring.
  • Payback Period: The number of years it takes for your cumulative energy savings to equal your net investment cost.

Key Factors Affecting Your Payback Period

1. Peak Sunlight Hours: This is not just "daylight," but the intensity of sun reaching your panels. A home in Arizona (5.5+ hours) will see a much faster ROI than a home in Washington (3 hours).

2. Utility Rates: The higher your current electricity rate, the more valuable every kilowatt-hour (kWh) your panels produce becomes. As utility companies increase rates annually (historically around 2-4%), your solar savings actually grow over time.

3. Incentives: The Federal Tax Credit currently allows homeowners to deduct 30% of the installation cost from their federal taxes, significantly shortening the payback period.

Example ROI Scenario

Consider a 6kW system costing $18,000. With a 30% federal tax credit ($5,400), the net cost is $12,600. If that system produces 8,500 kWh annually in a region where electricity costs $0.16/kWh, the first-year savings are $1,360. Including utility inflation, the payback period would be approximately 8.2 years. Over a 25-year panel lifespan, the total profit could exceed $35,000.

function calculateSolarROI() { var systemCost = parseFloat(document.getElementById("systemCost").value); var taxCredit = parseFloat(document.getElementById("taxCredit").value); var systemSize = parseFloat(document.getElementById("systemSize").value); var sunHours = parseFloat(document.getElementById("sunHours").value); var elecRate = parseFloat(document.getElementById("elecRate").value); var billIncrease = parseFloat(document.getElementById("billIncrease").value) / 100; if (isNaN(systemCost) || isNaN(systemSize) || isNaN(sunHours) || isNaN(elecRate)) { alert("Please enter valid numerical values."); return; } // Calculations var netCost = systemCost * (1 – (taxCredit / 100)); // Annual Production (kWh) = Size * sun hours * 365 days * efficiency (0.78 derate factor) var annualProduction = systemSize * sunHours * 365 * 0.78; var yearOneSavings = annualProduction * elecRate; // Calculate Payback Period with inflation var cumulativeSavings = 0; var paybackYears = 0; var currentYearSavings = yearOneSavings; var totalLifetimeSavings = 0; for (var year = 1; year = netCost && paybackYears === 0) { paybackYears = year – 1 + ((netCost – (cumulativeSavings – currentYearSavings)) / currentYearSavings); } totalLifetimeSavings += currentYearSavings; currentYearSavings *= (1 + billIncrease); } var netProfit = totalLifetimeSavings – netCost; // Display Results document.getElementById("netCostDisplay").innerHTML = "$" + netCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById("annualProdDisplay").innerHTML = Math.round(annualProduction).toLocaleString() + " kWh"; document.getElementById("yearOneSavings").innerHTML = "$" + yearOneSavings.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); if (paybackYears > 0 && paybackYears <= 25) { document.getElementById("paybackDisplay").innerHTML = paybackYears.toFixed(1) + " Years"; } else if (paybackYears === 0 && cumulativeSavings 25 Years"; } else { document.getElementById("paybackDisplay").innerHTML = "Instant ROI"; } document.getElementById("lifetimeSavingsDisplay").innerHTML = "$" + netProfit.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById("solarResults").style.display = "block"; }

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