This calculator estimates the daily energy production of a solar photovoltaic (PV) system based on key parameters. Solar panels convert sunlight into electricity, but their actual output can vary significantly due to factors like panel specifications, sunlight availability, and system efficiency.
How the Calculation Works
The calculation uses a simplified formula to estimate the daily energy output:
Daily Energy Output (kWh) = (Panel Rated Wattage × Number of Panels × Peak Sun Hours × Performance Ratio) / 1000
Panel Rated Wattage (Wp): This is the maximum power output a solar panel can produce under standard test conditions (STC). It's usually listed on the panel's datasheet. Higher wattage panels generate more power.
Number of Panels: The total count of solar panels installed in your system.
Peak Sun Hours: This represents the equivalent number of hours per day when solar irradiance averages 1000 W/m² (the standard test condition). It's a crucial factor reflecting the local climate and average sunlight intensity. A higher number of peak sun hours leads to greater energy production. This value is an average and can vary seasonally.
Performance Ratio (System Efficiency): This factor accounts for all the energy losses in the solar power system. It includes losses due to temperature, soiling, shading, inverter efficiency, wiring losses, and degradation over time. A typical performance ratio ranges from 0.75 to 0.90 (75% to 90%). A higher ratio indicates a more efficient system.
Division by 1000: This converts the total wattage-hours (Wh) into kilowatt-hours (kWh), the standard unit for measuring electrical energy.
Factors Affecting Real-World Output
While this calculator provides a good estimate, actual energy generation can differ due to:
Shading: Even partial shading of a panel can significantly reduce the output of the entire string.
Panel Orientation and Tilt Angle: The angle and direction your panels face relative to the sun's path greatly impact how much sunlight they receive throughout the day and year.
Temperature: Solar panels are less efficient at higher temperatures.
Weather Conditions: Cloud cover, dust, snow, and other atmospheric conditions reduce sunlight intensity.
System Degradation: Solar panels naturally lose a small percentage of their efficiency each year.
Use Cases
This calculator is useful for:
Homeowners considering a solar installation to estimate potential energy generation.
Solar installers to provide initial estimates to clients.
Researchers and students studying renewable energy.
Evaluating the performance of an existing solar PV system.
For precise sizing and financial projections, consult with a professional solar installer who can conduct a site-specific assessment.
var performanceRatioSlider = document.getElementById("performanceRatio");
var performanceRatioValueSpan = document.getElementById("performanceRatioValue");
performanceRatioSlider.oninput = function() {
var value = (this.value * 100).toFixed(0);
performanceRatioValueSpan.innerHTML = value + "%";
}
function calculateSolarOutput() {
var panelWattage = parseFloat(document.getElementById("panelWattage").value);
var numberOfPanels = parseFloat(document.getElementById("numberOfPanels").value);
var peakSunHours = parseFloat(document.getElementById("peakSunHours").value);
var performanceRatio = parseFloat(document.getElementById("performanceRatio").value);
var outputResultElement = document.getElementById("outputResult");
if (isNaN(panelWattage) || isNaN(numberOfPanels) || isNaN(peakSunHours) || isNaN(performanceRatio)) {
outputResultElement.innerHTML = "Invalid Input";
outputResultElement.style.color = "#dc3545";
return;
}
if (panelWattage <= 0 || numberOfPanels <= 0 || peakSunHours <= 0 || performanceRatio 1) {
outputResultElement.innerHTML = "Inputs must be positive";
outputResultElement.style.color = "#dc3545″;
return;
}
var dailyOutputWattHours = panelWattage * numberOfPanels * peakSunHours * performanceRatio;
var dailyOutputKiloWattHours = dailyOutputWattHours / 1000;
outputResultElement.innerHTML = dailyOutputKiloWattHours.toFixed(2) + " kWh";
outputResultElement.style.color = "#28a745"; // Success Green
}