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Solar Panel Savings Calculator

Estimated Savings Results

Daily Production 0 kWh
Monthly Savings $0.00
Annual Savings $0.00
25-Year Savings $0.00
function calculateSolarSavings() { var size = parseFloat(document.getElementById('systemSize').value); var sun = parseFloat(document.getElementById('sunlightHours').value); var rate = parseFloat(document.getElementById('electricityCost').value); var efficiency = parseFloat(document.getElementById('systemEfficiency').value) / 100; if (isNaN(size) || isNaN(sun) || isNaN(rate) || isNaN(efficiency)) { alert("Please fill in all fields with valid numbers."); return; } var dailyKwh = size * sun * efficiency; var dailyDollar = dailyKwh * rate; var monthlyDollar = dailyDollar * 30.44; var annualDollar = dailyDollar * 365; var lifetimeDollar = annualDollar * 25; document.getElementById('dailyGen').innerText = dailyKwh.toFixed(2) + " kWh"; document.getElementById('monthlySave').innerText = "$" + monthlyDollar.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('annualSave').innerText = "$" + annualDollar.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('lifetimeSave').innerText = "$" + lifetimeDollar.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 0}); document.getElementById('solarResult').style.display = 'block'; }

How to Calculate Solar Panel Savings

Switching to solar energy is one of the most effective ways to reduce your carbon footprint and slash your monthly utility bills. But how much can you actually save? This calculator uses your local sunlight data and system specifications to provide a realistic estimate of your return on investment.

Key Factors in the Calculation

  • System Size: Measured in kilowatts (kW), this is the maximum power output of your panels under ideal conditions. Most residential systems range from 5kW to 10kW.
  • Peak Sunlight Hours: This isn't just the time between sunrise and sunset. It refers to the intensity of sunlight equivalent to 1,000 watts per square meter. Most US states average 3.5 to 6 hours daily.
  • System Efficiency: No solar system is 100% efficient. Energy is lost through DC-to-AC conversion (inverters), wiring, and environmental factors like dust or heat. A standard conservative estimate is 75-80%.
  • Electricity Rate: Your local utility rate per kilowatt-hour (kWh). The higher your current rate, the more valuable every solar electron becomes.

The Solar Savings Formula

To calculate your daily energy production manually, use this formula:

Daily kWh = System Size (kW) × Sunlight Hours × Efficiency (0.75)

Once you have the daily production, multiply by your electricity rate to find your daily monetary savings. Multiply by 365 for your annual ROI.

Example Calculation

If you live in a sunny area like Arizona with a 6kW system, 5.5 peak sun hours, and an electricity rate of $0.14/kWh:

  1. Daily Production: 6kW × 5.5 hours × 0.75 = 24.75 kWh
  2. Daily Savings: 24.75 kWh × $0.14 = $3.46
  3. Annual Savings: $3.46 × 365 = $1,262.90
  4. 25-Year Lifetime Savings: Over $31,500!

Maximizing Your Solar ROI

To ensure your calculator results match reality, consider these maintenance tips:

Keep your panels clear of debris and shade. Even a small shadow from a growing tree can significantly drop the voltage of an entire string of panels. Additionally, monitor your inverter's performance monthly to catch any hardware failures early, ensuring you never miss a day of free energy from the sun.

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