Estimate your potential annual savings from a solar power system.
(Typical: 1000-1700 kWh per kWp depending on location, tilt, orientation)
(e.g., tax credits, state/local rebates)
Estimated Annual Savings
Understanding Your Solar Power Savings
This calculator helps you estimate the financial benefits of installing a solar power system for your home or business. It considers the system's size, its estimated energy production, your current electricity costs, the initial investment, and available incentives.
How it Works:
The calculation involves several key steps:
Estimated Annual Energy Production: This is the total amount of electricity (in kilowatt-hours, kWh) your solar panels are expected to generate over a year. It's calculated by multiplying the System Size (in kilowatts-peak, kWp) by the Estimated Annual Production factor (kWh/kWp). The factor varies significantly based on your geographical location, the angle and direction (orientation) of your panels, and shading.
Total Annual Production (kWh) = System Size (kWp) * Annual Production (kWh/kWp)
Gross Annual Savings: This represents the value of the electricity your solar system will produce. It's calculated by multiplying the Total Annual Production (kWh) by your Current Electricity Cost ($/kWh). This is the amount you would have paid your utility company for that same amount of electricity.
Gross Annual Savings ($) = Total Annual Production (kWh) * Electricity Cost ($/kWh)
Net System Cost: The actual upfront cost of the system after accounting for incentives. Incentives, such as federal tax credits, state rebates, or local grants, reduce the out-of-pocket expense.
Net System Cost ($) = Total System Cost ($) * (1 - Incentive Percentage / 100)
Simple Payback Period: This estimates how long it will take for the accumulated savings to equal the net cost of the system.
Simple Payback Period (Years) = Net System Cost ($) / Gross Annual Savings ($)
Return on Investment (ROI): A measure of the profitability of your solar investment over a longer period, assuming savings continue. For simplicity in this calculator, we'll approximate ROI over 25 years (a common lifespan for solar panels).
Total Savings over 25 Years = Gross Annual Savings ($) * 25 Net Profit over 25 Years = Total Savings over 25 Years - Net System Cost ($) ROI (%) = (Net Profit over 25 Years / Net System Cost ($)) * 100
Key Inputs Explained:
System Size (kW): The rated capacity of your solar power system. Larger systems generate more electricity but cost more.
Estimated Annual Production (kWh/kWp): A crucial factor reflecting how efficiently your panels convert sunlight into electricity in your specific location. Consult local solar installers for the most accurate estimates.
Current Electricity Cost ($/kWh): The price you pay your utility provider for electricity. Higher electricity costs mean greater savings from solar.
Total System Cost ($): The full price of the solar installation, including panels, inverters, mounting hardware, and labor.
Incentives/Rebates (%): Financial incentives that reduce your upfront cost. These can significantly shorten the payback period.
Disclaimer: This calculator provides an *estimate*. Actual savings may vary based on system performance, installation quality, electricity rate changes, maintenance, and unforeseen factors. It's recommended to obtain quotes from reputable solar installers for a precise assessment.
function calculateSolarSavings() {
var systemSize = parseFloat(document.getElementById("systemSize").value);
var annualProductionKwhPerKw = parseFloat(document.getElementById("annualProductionKwhPerKw").value);
var electricityCostPerKwh = parseFloat(document.getElementById("electricityCostPerKwh").value);
var systemCost = parseFloat(document.getElementById("systemCost").value);
var incentivePercentage = parseFloat(document.getElementById("incentivePercentage").value);
var resultDiv = document.getElementById("result");
var resultValue = document.getElementById("result-value");
var paybackPeriod = document.getElementById("payback-period");
var roiPercentage = document.getElementById("roi-percentage");
// Input Validation
if (isNaN(systemSize) || systemSize <= 0 ||
isNaN(annualProductionKwhPerKw) || annualProductionKwhPerKw <= 0 ||
isNaN(electricityCostPerKwh) || electricityCostPerKwh < 0 ||
isNaN(systemCost) || systemCost <= 0 ||
isNaN(incentivePercentage) || incentivePercentage 100) {
alert("Please enter valid positive numbers for all fields. Incentive percentage should be between 0 and 100.");
resultDiv.style.display = 'none';
return;
}
var totalAnnualProduction = systemSize * annualProductionKwhPerKw;
var grossAnnualSavings = totalAnnualProduction * electricityCostPerKwh;
var netSystemCost = systemCost * (1 – incentivePercentage / 100);
var simplePaybackYears = "N/A";
if (grossAnnualSavings > 0) {
simplePaybackYears = (netSystemCost / grossAnnualSavings).toFixed(1);
}
var totalSavings25Years = grossAnnualSavings * 25;
var netProfit25Years = totalSavings25Years – netSystemCost;
var roi25Years = "N/A";
if (netSystemCost > 0) {
roi25Years = (netProfit25Years / netSystemCost * 100).toFixed(1);
} else if (netProfit25Years > 0) {
roi25Years = "Infinity"; // If cost is 0 and savings are positive
}
resultValue.innerText = "$" + grossAnnualSavings.toFixed(2) + " per year";
paybackPeriod.innerText = "Simple Payback Period: " + simplePaybackYears + " years";
roiPercentage.innerText = "Estimated 25-Year ROI: " + roi25Years + "%";
resultDiv.style.display = 'block';
}