Monthly Salary to Daily Rate Calculator

Solar Panel Savings & ROI Calculator

Calculation Results

Net System Cost:

Annual Energy Production:

Estimated Annual Savings:

Payback Period:

25-Year Total Savings:

function calculateSolarSavings() { var bill = parseFloat(document.getElementById('monthlyBill').value); var rate = parseFloat(document.getElementById('kwhRate').value); var size = parseFloat(document.getElementById('systemSize').value); var sun = parseFloat(document.getElementById('sunHours').value); var cost = parseFloat(document.getElementById('totalCost').value); var credit = parseFloat(document.getElementById('taxCredit').value); if (isNaN(bill) || isNaN(rate) || isNaN(size) || isNaN(sun) || isNaN(cost) || isNaN(credit)) { alert("Please enter valid numeric values in all fields."); return; } var netCost = cost – (cost * (credit / 100)); var annualProduction = size * sun * 365; // kWh per year var annualSavings = annualProduction * rate; // Limit savings to not exceed actual bill significantly for realistic ROI var actualBillAnnual = bill * 12; var effectiveSavings = Math.min(annualSavings, actualBillAnnual); var paybackPeriod = netCost / effectiveSavings; var longTermSavings = (effectiveSavings * 25) – netCost; document.getElementById('resNetCost').innerText = "$" + netCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('resProduction').innerText = annualProduction.toLocaleString() + " kWh"; document.getElementById('resAnnualSavings').innerText = "$" + effectiveSavings.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('resPayback').innerText = paybackPeriod.toFixed(1) + " Years"; document.getElementById('resLongTerm').innerText = "$" + longTermSavings.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('solarResult').style.display = "block"; }

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How to Calculate Your Solar Panel Return on Investment

Switching to solar energy is a significant financial decision. To accurately estimate your savings, you must look beyond just the sticker price of the panels. This calculator helps you determine the Payback Period—the time it takes for your energy savings to cover the initial net cost of the system.

Key Factors in the Calculation

• System Size (kW): Most residential systems range from 5kW to 10kW. The larger the system, the more electricity it produces, but the higher the upfront cost.
• Peak Sun Hours: This isn't just daylight hours; it's the intensity of sunlight. For example, Arizona averages 5.7 hours, while Washington averages around 3.5 hours.
• Federal Solar Tax Credit (ITC): As of 2024, the federal government offers a 30% tax credit on the total cost of solar installation, significantly reducing the net investment.
• Electricity Rates: The higher your local utility rate per kWh, the faster your solar panels will pay for themselves.

Example Calculation

Imagine you install a 7kW system in a region with 4.5 sun hours per day. Your total cost is $21,000. After the 30% Federal Tax Credit ($6,300), your net cost is $14,700.

The system will produce approximately 11,497 kWh per year (7kW * 4.5 hours * 365 days). If your electricity rate is $0.18 per kWh, your annual savings would be roughly $2,069.

Payback Period: $14,700 ÷ $2,069 = 7.1 Years. Since solar panels typically last 25 years, you would enjoy nearly 18 years of virtually free electricity.

Why Solar ROI Matters

Understanding your solar ROI allows you to compare the investment against other financial vehicles. With typical payback periods ranging from 6 to 10 years and internal rates of return (IRR) often exceeding 10-15%, solar is frequently a more stable investment than the stock market for homeowners in high-sun or high-utility-cost areas.