Estimate your potential savings and payback period for a residential solar system.
Estimated Financial Outlook
Total Gross System Cost:$0.00
Net Cost (After Tax Credit):$0.00
Estimated Annual Energy Production:0 kWh
Estimated Annual Savings:$0.00
Payback Period (ROI):0 Years
Understanding Your Solar Investment
Switching to solar power is one of the most significant financial and environmental decisions a homeowner can make. This calculator helps you determine if the investment makes sense for your specific location and energy usage patterns.
Key Factors in Solar ROI
Several variables influence how quickly your solar panels pay for themselves:
Sunlight Exposure: Regions like Arizona or California will see a faster ROI than cloudier regions due to higher daily peak sunlight hours.
Local Electricity Rates: The more you pay your utility company per kWh, the more you save by generating your own power.
System Size: A properly sized system should aim to cover 100% of your energy needs without being excessively large, which increases upfront costs without proportional benefits.
Incentives: The Federal Investment Tax Credit (ITC) currently allows homeowners to deduct a significant percentage of the installation cost from their federal taxes.
Example Calculation
If you install a 6kW system at $3.00 per watt, your gross cost is $18,000. With a 30% federal tax credit, your net cost drops to $12,600. If that system produces 9,000 kWh per year and your local rate is $0.15/kWh, you save $1,350 annually. In this scenario, your payback period would be approximately 9.3 years.
Is Solar Worth It?
Most residential solar systems last 25 to 30 years. If your payback period is under 10-12 years, you are looking at 15+ years of essentially "free" electricity, making it a highly profitable long-term investment that also increases property value.
function calculateSolarROI() {
// Get Input Values
var monthlyBill = parseFloat(document.getElementById("monthlyBill").value);
var systemSize = parseFloat(document.getElementById("systemSize").value);
var costPerWatt = parseFloat(document.getElementById("costPerWatt").value);
var sunlightHours = parseFloat(document.getElementById("sunlightHours").value);
var elecRate = parseFloat(document.getElementById("elecRate").value);
var taxCreditPercent = parseFloat(document.getElementById("taxCredit").value);
// Validate Inputs
if (isNaN(monthlyBill) || isNaN(systemSize) || isNaN(costPerWatt) || isNaN(sunlightHours) || isNaN(elecRate) || isNaN(taxCreditPercent)) {
alert("Please enter valid numerical values in all fields.");
return;
}
// Logic
var grossCost = systemSize * 1000 * costPerWatt;
var taxCreditAmount = grossCost * (taxCreditPercent / 100);
var netCost = grossCost – taxCreditAmount;
// Annual Production: kW * Daily Sun Hours * Days in Year
var annualProduction = systemSize * sunlightHours * 365;
// Annual Savings: Production * Rate per kWh
var annualSavings = annualProduction * elecRate;
// Payback Period: Net Cost / Annual Savings
var paybackPeriod = 0;
if (annualSavings > 0) {
paybackPeriod = netCost / annualSavings;
}
// Display Results
document.getElementById("grossCost").innerText = "$" + grossCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("netCost").innerText = "$" + netCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("annualProduction").innerText = Math.round(annualProduction).toLocaleString() + " kWh";
document.getElementById("annualSavings").innerText = "$" + annualSavings.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
if (paybackPeriod > 0) {
document.getElementById("paybackPeriod").innerText = paybackPeriod.toFixed(1) + " Years";
} else {
document.getElementById("paybackPeriod").innerText = "N/A";
}
// Show result div
document.getElementById("solarResults").style.display = "block";
}