Estimate your solar ROI and annual electricity savings
Estimated Projections
Annual Savings
$0
Payback Period
0 Years
25-Year Total Savings
$0
System Size Needed
0 kW
🌿 Estimated Annual CO2 Reduction: 0 lbs
How Solar Panel Savings Are Calculated
Switching to solar energy is one of the most effective ways to reduce your monthly utility expenses and carbon footprint. Understanding the Return on Investment (ROI) involves several key metrics: monthly consumption, solar irradiance, and local electricity rates.
Key Variables in Solar Affordability
Monthly Bill: This determines the current cost you are looking to eliminate. Most solar systems are sized to cover 90-100% of this demand.
Sunlight Hours: This is not just daylight, but "peak sun hours" where the sun's intensity is sufficient for energy production. A home in Arizona will require a smaller system than a home in Washington for the same energy output.
System Size: To offset your bill, we calculate: (Monthly kWh) / (Sunlight Hours * 30 days). This gives the kW capacity needed for your roof.
Example ROI Calculation
Let's say your monthly bill is $150 and your local rate is $0.15/kWh. This means you consume approximately 1,000 kWh per month.
Example: If a 7kW system costs $15,000 and saves you $1,800 annually, your payback period is 8.33 years. Over a 25-year warranty period, you would save $45,000 in energy costs, resulting in a net profit of $30,000.
Don't Forget Incentives
The Federal Investment Tax Credit (ITC) can reduce your system cost by up to 30%. This calculator provides a gross estimate; applying local state rebates and the federal tax credit can often reduce your payback period by another 2-3 years.
function calculateSolarSavings() {
var monthlyBill = parseFloat(document.getElementById("monthlyBill").value);
var rate = parseFloat(document.getElementById("electricityRate").value);
var sunHours = parseFloat(document.getElementById("sunlightHours").value);
var cost = parseFloat(document.getElementById("systemCost").value);
if (isNaN(monthlyBill) || isNaN(rate) || isNaN(sunHours) || isNaN(cost) || monthlyBill <= 0) {
alert("Please enter valid positive numbers for all fields.");
return;
}
// Monthly kWh consumption
var monthlyKwh = monthlyBill / rate;
// Required System Size in kW (approximate)
// Formula: Monthly Consumption / (30 days * Sun Hours)
var sizeNeeded = monthlyKwh / (30 * sunHours);
// Annual Savings
var annualSavingsVal = monthlyBill * 12;
// Payback Period (years)
var payback = cost / annualSavingsVal;
// 25-Year Lifetime Savings (assuming electricity prices rise 2% per year on average, but simple calc for clarity)
var lifetimeSavings = annualSavingsVal * 25;
// CO2 reduction (approx 0.85 lbs CO2 per kWh)
var co2Saved = monthlyKwh * 12 * 0.85;
// Update UI
document.getElementById("annualSavings").innerText = "$" + annualSavingsVal.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 0});
document.getElementById("paybackPeriod").innerText = payback.toFixed(1) + " Years";
document.getElementById("totalLifetime").innerText = "$" + lifetimeSavings.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 0});
document.getElementById("systemSize").innerText = sizeNeeded.toFixed(2) + " kW";
document.getElementById("co2Reduction").innerText = Math.round(co2Saved).toLocaleString();
document.getElementById("resultsArea").style.display = "block";
}