Calculate your solar investment payback period and 25-year savings
Net System Cost$0
Est. Monthly Production0 kWh
Payback Period0 Years
25-Year Net Savings$0
How to Use the Solar Panel Savings Calculator
Switching to solar energy is a significant financial decision. This calculator helps you understand the return on investment (ROI) by analyzing your current energy consumption against the potential output of a residential solar system. To get the most accurate estimate, follow these steps:
Monthly Bill: Enter the average amount you pay each month for electricity.
Price per kWh: Check your utility bill for the "Rate" or "Cost per kWh." The US average is approximately $0.16.
System Size: Residential systems typically range from 5kW to 15kW. A standard 2,000 sq. ft. home often needs about 8kW.
Federal Tax Credit: Currently, the Federal Solar Investment Tax Credit (ITC) allows you to deduct 30% of your installation costs from your federal taxes.
Daily Sun Hours: This is not total daylight, but "peak sun hours." Most US states average between 3.5 and 5.5 hours.
Understanding Solar ROI
The Solar Payback Period is the time it takes for the monthly energy savings to equal the initial net cost of the system. Most homeowners reach this "break-even" point within 6 to 10 years. After this period, the electricity generated is essentially free for the remaining life of the panels, which is typically 25 to 30 years.
Example Calculation
If you have an 8kW system costing $20,000, the 30% Federal Tax Credit reduces your net cost to $14,000. If that system produces $160 worth of electricity monthly, your annual savings are $1,920. In this scenario, your payback period would be roughly 7.3 years.
Key Factors Affecting Your Savings
Several variables can influence your final results:
Roof Orientation: South-facing roofs generate the most power in the Northern Hemisphere.
Local Incentives: Some states or utility companies offer additional rebates or Performance-Based Incentives (PBIs).
Utility Rate Hikes: Historically, electricity rates increase by 2-3% annually. This makes solar savings even more valuable over time.
Net Metering: This policy allows you to "sell" excess energy back to the grid during the day and use those credits at night.
function calculateSolarResults() {
var bill = parseFloat(document.getElementById('monthlyBill').value);
var rate = parseFloat(document.getElementById('priceKWh').value);
var size = parseFloat(document.getElementById('systemSize').value);
var cost = parseFloat(document.getElementById('systemCost').value);
var credit = parseFloat(document.getElementById('taxCredit').value);
var sunHours = parseFloat(document.getElementById('sunHours').value);
if (isNaN(bill) || isNaN(rate) || isNaN(size) || isNaN(cost) || isNaN(credit) || isNaN(sunHours)) {
alert("Please enter valid numerical values in all fields.");
return;
}
// 1. Calculate Net Cost
var netCost = cost – (cost * (credit / 100));
// 2. Calculate Monthly Production (kWh)
// Formula: Size (kW) * Daily Sun Hours * 30.4 days * Efficiency (usually ~78% after losses)
var monthlyProduction = size * sunHours * 30.4 * 0.78;
// 3. Calculate Monthly Savings ($)
// We assume the user can use all produced energy via net metering or direct use
var potentialMonthlySavings = monthlyProduction * rate;
// Cap savings at the actual bill amount (unless they get paid for excess, which varies by state)
var actualMonthlySavings = Math.min(bill, potentialMonthlySavings);
var annualSavings = actualMonthlySavings * 12;
// 4. Payback Period
var paybackYears = netCost / annualSavings;
// 5. 25-Year Net Savings
// We assume a 2.5% annual utility rate increase for more realistic long-term forecasting
var totalSavings25 = 0;
var currentYearSavings = annualSavings;
for (var i = 1; i 25) {
document.getElementById('paybackResult').innerText = '25+ Years';
} else {
document.getElementById('paybackResult').innerText = paybackYears.toFixed(1) + ' Years';
}
document.getElementById('totalSavingsResult').innerText = '$' + netProfit25.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 0});
// Smooth scroll to results
document.getElementById('results-area').scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}