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Solar Panel Savings & ROI Calculator

Annual Savings $0.00
Payback Period 0 Years
25-Year Net Profit $0.00
CO2 Offset (Annual) 0 lbs
function calculateSolarROI() { var bill = parseFloat(document.getElementById('monthlyBill').value); var cost = parseFloat(document.getElementById('systemCost').value); var size = parseFloat(document.getElementById('systemSize').value); var hours = parseFloat(document.getElementById('sunHours').value); if (isNaN(bill) || isNaN(cost) || isNaN(size) || isNaN(hours)) { alert("Please enter valid numbers in all fields."); return; } // Calculations // Assume the system covers 90% of the bill on average var annualBillSavings = bill * 12 * 0.95; // Generate Energy (kWh) = Size * sunHours * 365 * 0.78 (Efficiency loss factor) var annualKwhGenerated = size * hours * 365 * 0.78; // Environmental Impact: ~0.85 lbs of CO2 per kWh var co2Saved = annualKwhGenerated * 0.85; var yearsToPayback = cost / annualBillSavings; // 25-year profit calculation accounting for 2% annual energy cost increase var totalSavings25Years = 0; var currentYearSavings = annualBillSavings; for (var i = 0; i < 25; i++) { totalSavings25Years += currentYearSavings; currentYearSavings *= 1.02; } var netProfit = totalSavings25Years – cost; // Display Results document.getElementById('solar-results').style.display = 'block'; document.getElementById('annualSavings').innerText = '$' + annualBillSavings.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('paybackPeriod').innerText = yearsToPayback.toFixed(1) + ' Years'; document.getElementById('totalProfit').innerText = '$' + netProfit.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 0}); document.getElementById('co2Offset').innerText = co2Saved.toLocaleString(undefined, {maximumFractionDigits: 0}) + ' lbs'; }

How to Use the Solar ROI Calculator

Switching to solar energy is a significant financial decision. This calculator helps you estimate the Return on Investment (ROI) by analyzing your current energy spending against the cost of a photovoltaic (PV) system. To get the most accurate results, use the "net cost" of your system—this is the total price minus the Federal Solar Tax Credit (ITC) and any local rebates.

Understanding the Key Metrics

  • Annual Savings: This is the estimated amount you will save on your utility bills. We assume a 95% offset of your current bill, as most grid-tied systems still involve a small monthly connection fee.
  • Payback Period: Also known as the "break-even point," this represents how many years it takes for the energy savings to fully cover the initial investment cost. In the US, the average is between 6 and 10 years.
  • 25-Year Net Profit: Solar panels are typically warrantied for 25 years. This figure calculates your total savings over that lifespan, accounting for a modest 2% annual increase in utility electricity rates.
  • CO2 Offset: Solar isn't just a financial win; it's an environmental one. This shows how many pounds of carbon dioxide emissions you prevent each year by generating clean energy.

Example Calculation

Scenario: A homeowner in Arizona with a $200 monthly bill installs an 8kW system costing $16,000 (after tax credits).

If they receive 5.5 peak sun hours per day, their annual savings would be approximately $2,280. This results in a payback period of just 7 years. Over 25 years, the total net profit would exceed $55,000, while offsetting over 13,000 lbs of CO2 annually.

Factors That Affect Your Solar ROI

Several variables can shift these numbers. Your roof's orientation (South-facing is best in the Northern Hemisphere), the tilt of your panels, and local "Net Metering" policies play a massive role. Net Metering allows you to sell excess energy back to the grid at retail rates, which significantly accelerates your ROI. If your utility company only offers wholesale rates for excess power, your payback period may be slightly longer unless you incorporate battery storage.

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