Determine the financial viability of your solar investment in seconds.
Gross Installation Cost:$0.00
Net Cost (After Incentives):$0.00
Est. Annual Energy Production:0 kWh
Annual Utility Savings:$0.00
Payback Period:0 Years
25-Year Total Net Profit:$0.00
How to Calculate Your Solar Return on Investment (ROI)
Switching to solar energy is a major financial decision. Understanding the Solar Panel ROI helps you determine if the long-term energy savings outweigh the initial installation costs. Typically, solar systems have a lifespan of 25 to 30 years, making them a high-yield long-term asset.
Key Factors Influencing Your Payback Period
System Efficiency: Not all sunlight is converted to electricity. We use a standard 78% efficiency factor to account for inverter losses, wiring, and dirt.
Peak Sun Hours: This isn't just daylight hours, but the intensity of sunlight. Areas like Arizona have higher peak sun hours than Washington state.
The Federal ITC: The Investment Tax Credit (ITC) currently allows homeowners to deduct 30% of the cost of installing a solar energy system from their federal taxes.
Utility Rates: The more you pay your utility company per kWh, the faster your solar system pays for itself.
Realistic Example Calculation
If you install a 6kW system at $3.00 per watt, your gross cost is $18,000. After a 30% Federal Tax Credit, your net cost drops to $12,600. If your area receives 4.5 peak sun hours daily, you'll generate roughly 7,700 kWh per year. At a utility rate of $0.15/kWh, you save $1,155 annually. In this scenario, your system pays for itself in approximately 10.9 years.
Why Maintenance Matters
While solar panels have no moving parts, annual inspections and occasional cleaning are recommended. Our calculator includes an optional annual maintenance field to ensure your ROI estimate is as realistic as possible by accounting for these minor overheads.
function calculateSolarROI() {
// Get Input Values
var systemSizeKw = parseFloat(document.getElementById('systemSize').value);
var costPerWatt = parseFloat(document.getElementById('costPerWatt').value);
var sunHours = parseFloat(document.getElementById('sunHours').value);
var elecRate = parseFloat(document.getElementById('elecRate').value);
var incentivesPercent = parseFloat(document.getElementById('incentives').value);
var maintCost = parseFloat(document.getElementById('maintenance').value);
// Validate Inputs
if (isNaN(systemSizeKw) || isNaN(costPerWatt) || isNaN(sunHours) || isNaN(elecRate) || isNaN(incentivesPercent)) {
alert("Please enter valid numerical values for all required fields.");
return;
}
// Calculations
var grossCost = (systemSizeKw * 1000) * costPerWatt;
var incentiveAmount = grossCost * (incentivesPercent / 100);
var netCost = grossCost – incentiveAmount;
// Daily Production: Size * Hours * 0.78 (Standard Efficiency Derate Factor)
var dailyKwh = systemSizeKw * sunHours * 0.78;
var annualKwh = dailyKwh * 365;
// Financials
var annualGrossSavings = annualKwh * elecRate;
var annualNetSavings = annualGrossSavings – maintCost;
var paybackYears = netCost / annualNetSavings;
// 25 Year Outlook
var totalSavings25 = annualNetSavings * 25;
var totalProfit = totalSavings25 – netCost;
// Display Results
document.getElementById('solarResults').style.display = 'block';
document.getElementById('resGrossCost').innerText = '$' + grossCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resNetCost').innerText = '$' + netCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resProduction').innerText = Math.round(annualKwh).toLocaleString() + ' kWh / yr';
document.getElementById('resAnnualSavings').innerText = '$' + annualNetSavings.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
if (annualNetSavings <= 0) {
document.getElementById('resPayback').innerText = "Never (Maint. exceeds savings)";
} else {
document.getElementById('resPayback').innerText = paybackYears.toFixed(1) + ' Years';
}
document.getElementById('resProfit').innerText = '$' + totalProfit.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
// Scroll to results on mobile
if (window.innerWidth < 600) {
document.getElementById('solarResults').scrollIntoView({ behavior: 'smooth' });
}
}