Use this calculator to estimate the number of solar panels you might need, the total system size, and your potential annual energy production and savings based on your daily energy consumption and local solar conditions.
Estimated Solar System Details:
Number of Panels Needed:
Total System Size: kW
Estimated Annual Energy Production: kWh
Estimated Annual Savings:
Understanding Your Solar Power Potential
Going solar is a significant step towards energy independence and reducing your carbon footprint. This "Free Solar Power Calculator" helps you get a preliminary estimate of what a solar panel system might look like for your home or business.
How the Calculator Works:
The calculator uses several key inputs to determine your potential solar energy generation:
Average Daily Energy Consumption (kWh/day): This is the most crucial factor. It represents how much electricity your household uses on an average day. You can usually find this on your electricity bill. The goal of a solar system is often to offset a significant portion, if not all, of this consumption.
Average Peak Sun Hours (hours/day): This refers to the equivalent number of hours per day when the intensity of sunlight averages 1,000 watts per square meter. It's not just about how long the sun is out, but how strong it is. This value varies significantly by geographic location and time of year. For example, a sunny state like Arizona might have 5-6 peak sun hours, while a cloudier region might have 3-4.
Individual Solar Panel Wattage (Watts): This is the power output rating of a single solar panel under standard test conditions. Common panel wattages range from 300W to 450W or more. Higher wattage panels mean fewer panels are needed for the same total system size.
System Losses (%): No solar system operates at 100% efficiency in real-world conditions. Losses occur due to factors like temperature (panels produce less in very hot conditions), wiring resistance, dust and dirt accumulation, shading, and inverter efficiency. A typical system loss factor ranges from 10% to 20%.
Average Electricity Cost ($/kWh): This input allows the calculator to estimate your potential financial savings. By knowing how much you currently pay for each kilowatt-hour of electricity, we can project how much money you could save by generating your own power.
What the Results Mean:
Number of Panels Needed: This is an estimate of how many individual solar panels you would require to meet your daily energy consumption, considering your local sun hours and system losses.
Total System Size (kW): This represents the total power capacity of your solar array in kilowatts (kW). For example, a 6 kW system is common for many residential homes.
Estimated Annual Energy Production (kWh): This is the total amount of electricity your estimated solar system could generate over a year, measured in kilowatt-hours.
Estimated Annual Savings: This figure shows the approximate amount of money you could save annually on your electricity bills by generating your own power.
Important Note: This calculator provides a preliminary estimate. For an accurate assessment and system design, it is crucial to consult with a professional solar installer. They can conduct a detailed site evaluation, consider specific shading issues, roof characteristics, local regulations, and provide a precise quote tailored to your needs.
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function calculateSolarPower() {
var dailyConsumption = parseFloat(document.getElementById("dailyConsumption").value);
var peakSunHours = parseFloat(document.getElementById("peakSunHours").value);
var panelWattage = parseFloat(document.getElementById("panelWattage").value);
var systemLosses = parseFloat(document.getElementById("systemLosses").value);
var electricityCost = parseFloat(document.getElementById("electricityCost").value);
// Input validation
if (isNaN(dailyConsumption) || dailyConsumption <= 0) {
alert("Please enter a valid positive number for Average Daily Energy Consumption.");
return;
}
if (isNaN(peakSunHours) || peakSunHours <= 0) {
alert("Please enter a valid positive number for Average Peak Sun Hours.");
return;
}
if (isNaN(panelWattage) || panelWattage <= 0) {
alert("Please enter a valid positive number for Individual Solar Panel Wattage.");
return;
}
if (isNaN(systemLosses) || systemLosses = 100) {
alert("Please enter a valid percentage (0-99) for System Losses.");
return;
}
if (isNaN(electricityCost) || electricityCost <= 0) {
alert("Please enter a valid positive number for Average Electricity Cost.");
return;
}
// Convert system losses percentage to a multiplier
var efficiencyMultiplier = (100 – systemLosses) / 100;
// 1. Energy produced by one panel per day (kWh)
// (Panel Wattage / 1000 to convert Watts to kW) * Peak Sun Hours * Efficiency Multiplier
var dailyKWhPerPanel = (panelWattage / 1000) * peakSunHours * efficiencyMultiplier;
// Handle case where dailyKWhPerPanel might be zero or very small due to inputs
if (dailyKWhPerPanel <= 0) {
document.getElementById("panelsNeeded").innerText = "N/A (Check inputs)";
document.getElementById("systemSize").innerText = "N/A";
document.getElementById("annualProduction").innerText = "N/A";
document.getElementById("annualSavings").innerText = "N/A";
alert("Calculated daily energy production per panel is zero or negative. Please check your inputs, especially Peak Sun Hours and System Losses.");
return;
}
// 2. Number of panels needed (round up to the nearest whole panel)
var numPanels = Math.ceil(dailyConsumption / dailyKWhPerPanel);
// 3. Total system size (kW)
var totalSystemKW = (numPanels * panelWattage) / 1000;
// 4. Annual energy production (kWh)
var annualKWhProduction = dailyKWhPerPanel * numPanels * 365;
// 5. Annual savings ($)
var annualSavings = annualKWhProduction * electricityCost;
// Display results
document.getElementById("panelsNeeded").innerText = numPanels.toFixed(0);
document.getElementById("systemSize").innerText = totalSystemKW.toFixed(2);
document.getElementById("annualProduction").innerText = annualKWhProduction.toFixed(0);
document.getElementById("annualSavings").innerText = "$" + annualSavings.toFixed(2);
}
// Run calculation on page load with default values
window.onload = function() {
calculateSolarPower();
};