How Do You Calculate Interest on a Cd

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Solar Panel ROI & Payback Calculator

Investment Summary

Net System Cost:

Annual Energy Production:

Annual Savings:

Payback Period:

Estimated 25-Year Total Profit:

function calculateSolarROI() { var size = parseFloat(document.getElementById('systemSize').value); var cost = parseFloat(document.getElementById('totalCost').value); var sun = parseFloat(document.getElementById('sunHours').value); var rate = parseFloat(document.getElementById('elecRate').value); var credit = parseFloat(document.getElementById('taxCredit').value); if (isNaN(size) || isNaN(cost) || isNaN(sun) || isNaN(rate) || isNaN(credit)) { alert('Please enter valid numerical values in all fields.'); return; } var netCost = cost – credit; // 0.75 accounts for standard system efficiency losses (inverter, wiring, dust) var dailyKWh = size * sun * 0.75; var annualKWh = dailyKWh * 365; var annualSavings = annualKWh * rate; var paybackYears = netCost / annualSavings; // 25-year lifetime is industry standard var lifetimeSavings = annualSavings * 25; var totalProfit = lifetimeSavings – netCost; document.getElementById('resNetCost').innerText = '$' + netCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('resAnnualGen').innerText = Math.round(annualKWh).toLocaleString() + ' kWh'; document.getElementById('resAnnualSavings').innerText = '$' + annualSavings.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('resPayback').innerText = paybackYears.toFixed(1) + ' Years'; document.getElementById('resTotalROI').innerText = '$' + totalProfit.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('solar-results').style.display = 'block'; }

Understanding Your Solar Panel ROI: A Comprehensive Guide

Switching to solar power is one of the most significant financial and environmental decisions a homeowner can make. To determine if the investment makes sense, you need to look beyond the initial price tag and understand the Return on Investment (ROI) and the Payback Period.

Key Factors in Solar Calculations

  • System Size (kW): The total capacity of your panels. A typical residential system ranges from 5kW to 10kW.
  • Peak Sun Hours: This isn't just daylight; it's the amount of time the sun's intensity is sufficient to generate maximum power. Southwestern states often see 5.5+ hours, while Northern states may average 3.5.
  • Federal Tax Credit (ITC): As of 2024, the federal government offers a 30% tax credit on the total cost of your solar installation.
  • Utility Rates: The more you pay your power company per kilowatt-hour (kWh), the more money you save by producing your own electricity.

How to Calculate Solar Payback

The payback period is the time it takes for your annual electricity savings to cover the "net cost" of your system. The formula used by our calculator is:

(Total Cost – Incentives) / Annual Electricity Savings = Payback Period (Years)

Real-World Example

Imagine a homeowner in Florida installing a 7kW system:

  1. Gross Cost: $21,000
  2. 30% Federal Credit: -$6,300
  3. Net Cost: $14,700
  4. Annual Generation: 11,000 kWh (based on 4.8 sun hours)
  5. Annual Savings: $1,650 (at $0.15/kWh)
  6. Payback Period: 8.9 Years

Since most solar panels are warrantied for 25 years, this homeowner would enjoy over 16 years of "free" electricity, leading to a massive lifetime ROI.

Is Solar Right for You?

While the math often checks out, consider your roof's age and orientation. South-facing roofs with a 30-degree pitch typically yield the best results. If your roof is heavily shaded or needs replacement in the next 3 years, it's best to address those issues before installing solar panels.

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