.solar-calc-header { background: #2e7d32; color: #ffffff; padding: 30px; text-align: center; }
.solar-calc-header h1 { margin: 0; font-size: 28px; color: #ffffff; }
.solar-calc-container { padding: 30px; background: #fff; }
.solar-calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin-bottom: 25px; }
.solar-calc-field { margin-bottom: 15px; }
.solar-calc-field label { display: block; font-weight: 600; margin-bottom: 8px; font-size: 14px; color: #444; }
.solar-calc-field input { width: 100%; padding: 12px; border: 1px solid #ccc; border-radius: 4px; font-size: 16px; box-sizing: border-box; }
.solar-calc-btn { background: #f9a825; color: #000; border: none; padding: 15px 30px; font-size: 18px; font-weight: bold; border-radius: 4px; cursor: pointer; width: 100%; transition: background 0.3s; }
.solar-calc-btn:hover { background: #fbc02d; }
#solar-result-box { margin-top: 25px; padding: 20px; border-radius: 6px; display: none; text-align: center; }
.result-success { background: #e8f5e9; border: 1px solid #c8e6c9; }
.result-value { font-size: 32px; font-weight: 800; color: #2e7d32; display: block; margin: 10px 0; }
.solar-content { padding: 30px; background: #f9f9f9; border-top: 1px solid #eee; }
.solar-content h2 { color: #2e7d32; font-size: 24px; margin-top: 25px; }
.solar-content p { margin-bottom: 15px; }
.solar-example { background: #fff; padding: 20px; border-left: 5px solid #2e7d32; margin: 20px 0; }
@media (max-width: 600px) { .solar-calc-grid { grid-template-columns: 1fr; } }
function calculateSolarROI() {
var cost = parseFloat(document.getElementById('sc_totalCost').value);
var rebates = parseFloat(document.getElementById('sc_taxCredit').value);
var monthlySavings = parseFloat(document.getElementById('sc_monthlyBill').value);
var maintenance = parseFloat(document.getElementById('sc_maintenance').value);
var inflation = parseFloat(document.getElementById('sc_energyIncrease').value) / 100;
var life = parseFloat(document.getElementById('sc_systemLife').value);
var resultBox = document.getElementById('solar-result-box');
var resultText = document.getElementById('solar-result-text');
if (isNaN(cost) || isNaN(monthlySavings) || cost <= 0) {
resultBox.style.display = "block";
resultBox.className = "result-success";
resultBox.style.backgroundColor = "#ffebee";
resultText.innerHTML = "Please enter valid values for cost and savings.";
return;
}
var netCost = cost – rebates;
var cumulativeSavings = 0;
var years = 0;
var annualSavings = (monthlySavings * 12) – maintenance;
var totalLifetimeSavings = 0;
// Loop to find break-even year
var foundPayback = false;
var paybackYear = 0;
for (var i = 1; i = netCost) {
paybackYear = i;
foundPayback = true;
}
// Increase annual savings by inflation rate for next year
annualSavings = annualSavings * (1 + inflation);
}
var lifetimeProfit = totalLifetimeSavings – netCost;
resultBox.style.display = "block";
resultBox.className = "result-success";
resultBox.style.backgroundColor = "#e8f5e9";
var htmlOutput = "";
if (foundPayback) {
htmlOutput += "Estimated Payback Period:";
htmlOutput += "" + paybackYear + " Years";
htmlOutput += "After this point, your solar energy is essentially free!";
} else {
htmlOutput += "Estimated Payback Period:";
htmlOutput += "Over " + life + " Years";
htmlOutput += "The system does not pay for itself within the specified lifespan. Consider reducing costs or increasing system efficiency.";
}
htmlOutput += "
"; htmlOutput += "Total Savings over " + life + " years: $" + Math.round(totalLifetimeSavings).toLocaleString() + ""; htmlOutput += "Net Profit: $" + Math.round(lifetimeProfit).toLocaleString() + ""; resultText.innerHTML = htmlOutput; }
Solar Panel Payback Period Calculator
Calculate your Return on Investment (ROI) for Home Solar Energy
Understanding the Solar Payback Period
Investing in solar panels is not just an environmental choice; it is a significant financial decision. The Solar Payback Period is the amount of time it takes for the energy bill savings generated by your solar system to equal the initial net cost of installation.
Key Factors That Influence Your ROI
- Initial Net Cost: This is the gross cost of hardware and labor minus the Federal Solar Tax Credit (ITC) and local state rebates.
- Energy Consumption: The more electricity you use, the more you stand to save by switching to solar.
- Local Utility Rates: Homeowners in areas with high electricity rates see a much faster payback period.
- Net Metering Policies: If your utility company buys back excess energy at retail rates, your savings will accumulate significantly faster.
Realistic Example:
A $20,000 system with a 30% federal tax credit ($6,000) costs $14,000 net. If that system saves you $180 a month on electricity, you would save $2,160 in the first year. Even without considering rising energy costs, your payback period would be roughly 6.5 years.
A $20,000 system with a 30% federal tax credit ($6,000) costs $14,000 net. If that system saves you $180 a month on electricity, you would save $2,160 in the first year. Even without considering rising energy costs, your payback period would be roughly 6.5 years.
How This Calculator Works
Our tool uses a dynamic calculation model. Unlike simple division, this calculator accounts for energy inflation. Utility companies typically raise rates by 2% to 5% annually. This means your solar savings actually increase every year you own the system, shortening your payback period and increasing your long-term profit.
Long-Term Benefits After Payback
Once you reach the "break-even" point, every dollar saved on your utility bill is pure profit. Most modern Tier-1 solar panels are warrantied for 25 years. If your payback period is 7 years, you will enjoy 18 years of virtually free electricity.
"; htmlOutput += "Total Savings over " + life + " years: $" + Math.round(totalLifetimeSavings).toLocaleString() + ""; htmlOutput += "Net Profit: $" + Math.round(lifetimeProfit).toLocaleString() + ""; resultText.innerHTML = htmlOutput; }