Dollar Cost Average Calculator

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Solar Panel ROI Calculator

Estimate your payback period and 25-year financial gains from solar energy.

Net System Cost $0
Payback Period 0 Years
25-Year Total Savings $0
Return on Investment (ROI) 0%

How to Calculate Solar Panel ROI

Investing in solar panels is not just an environmental decision; it's a significant financial maneuver. To understand your Solar Panel ROI, you must look beyond the initial sticker price. The true cost is the "Net Cost"—the amount you pay after deducting the Federal Investment Tax Credit (ITC) and local utility rebates.

The Payback Period is the most critical metric for homeowners. This is the amount of time it takes for your cumulative electricity bill savings to equal the net cost of the system. In the United States, the average solar payback period ranges between 6 to 10 years.

Key Factors in Your Financial Projection

  • The Federal Tax Credit: Currently, the residential clean energy credit allows you to deduct 30% of your solar costs from your federal taxes.
  • Utility Rate Inflation: Average utility rates increase by about 2-4% annually. As grid power gets more expensive, your solar energy becomes more valuable.
  • Panel Degradation: Most modern solar panels are warrantied for 25 years but lose roughly 0.5% efficiency each year. Our calculator accounts for this production dip.
  • Maintenance: Solar systems are generally low-maintenance, but occasional cleaning or inverter repairs should be factored in.

Example Calculation

If you purchase a system for $20,000 and receive a $6,000 federal tax credit, your net investment is $14,000. If that system produces 10,000 kWh per year and your utility charges $0.16/kWh, you save $1,600 in the first year. Even without electricity price hikes, your payback would be 8.75 years. However, when you factor in a 3.5% annual utility inflation, that payback period often drops to 7 years or less.

function calculateSolarROI() { var grossCost = parseFloat(document.getElementById('grossCost').value); var incentives = parseFloat(document.getElementById('incentives').value); var annualProduction = parseFloat(document.getElementById('annualProduction').value); var utilityRate = parseFloat(document.getElementById('utilityRate').value); var elecInflation = parseFloat(document.getElementById('elecInflation').value) / 100; var maintenance = parseFloat(document.getElementById('maintenance').value); if (isNaN(grossCost) || isNaN(incentives) || isNaN(annualProduction) || isNaN(utilityRate)) { alert("Please enter valid numbers in all required fields."); return; } var netCost = grossCost – incentives; var cumulativeSavings = 0; var paybackYear = 0; var total25YearSavings = 0; var foundPayback = false; // Standard panel degradation rate (0.5% per year) var degradation = 0.005; for (var year = 1; year = netCost) { // Simple linear interpolation for more accurate payback month/year var prevYearSavings = cumulativeSavings – yearlySavings; var deficit = netCost – prevYearSavings; paybackYear = (year – 1) + (deficit / yearlySavings); foundPayback = true; } if (year === 25) { total25YearSavings = cumulativeSavings; } } var totalProfit = total25YearSavings – netCost; var roiPercentage = (totalProfit / netCost) * 100; // Display Results document.getElementById('resNetCost').innerText = "$" + netCost.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 0}); document.getElementById('resPayback').innerText = foundPayback ? paybackYear.toFixed(1) + " Years" : "Over 25 Years"; document.getElementById('resTotalSavings').innerText = "$" + total25YearSavings.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 0}); document.getElementById('resROI').innerText = roiPercentage.toFixed(1) + "%"; document.getElementById('solarResults').style.display = "block"; // Smooth scroll to results document.getElementById('solarResults').scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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