Average hours per day your panels receive direct sunlight.
Accounts for shading, dirt, temperature, inverter efficiency (typically 0.75 to 0.90).
Understanding Solar Power Production
This calculator estimates the daily and monthly energy (in kilowatt-hours, kWh) a solar photovoltaic (PV) system is expected to produce. Solar energy production is influenced by several factors, including the total capacity of your solar panels, the amount of sunlight they receive, and the efficiency of your system.
How it Works
The calculation is based on a standard formula for estimating solar PV energy generation:
Daily Energy (kWh) = Panel Wattage (Wp) * Number of Panels * Peak Sun Hours * System Loss Factor
Let's break down the components:
Panel Wattage (Wp): This is the rated power output of a single solar panel under Standard Test Conditions (STC). It's usually measured in Watts peak (Wp).
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 1,000 W/m² (which is the STC standard). It's not the same as total daylight hours; it accounts for the intensity of the sun. Values vary significantly by geographical location and season.
System Loss Factor: No solar system is 100% efficient. This factor accounts for energy losses due to factors like:
Shading: Obstructions blocking sunlight.
Temperature: Panel efficiency decreases as temperature rises.
Dirt and Soiling: Accumulation of dust and debris on panels.
Inverter Efficiency: Converting DC power from panels to AC power for your home.
Wiring Losses: Resistance in the electrical connections.
Module Mismatch: Slight variations in performance between panels.
A typical system loss factor ranges from 0.75 (75% efficient) to 0.90 (90% efficient).
The result is initially calculated in Watt-hours (Wh) and then converted to kilowatt-hours (kWh) by dividing by 1000.
Monthly Energy (kWh) = Daily Energy (kWh) * 30 (average days in a month)
Why Use This Calculator?
This calculator is useful for:
Estimating Potential Savings: Understanding how much energy your system might generate helps in estimating potential reductions in your electricity bills.
System Sizing: While this calculator estimates production, it can help in confirming if a proposed system size aligns with expectations for your location.
Comparing Options: If you're considering different panel types or system configurations, this can provide a baseline for comparison.
Understanding Solar Performance: It provides a tangible metric (kWh) to grasp the output of a solar installation.
Disclaimer: This calculator provides an estimation for informational purposes only. Actual solar energy production can vary due to many real-world factors not precisely captured by these inputs. For accurate assessments, consult with a qualified solar professional.
function calculateSolarProduction() {
var panelWattageInput = document.getElementById("panelWattage");
var numberOfPanelsInput = document.getElementById("numberOfPanels");
var peakSunHoursInput = document.getElementById("peakSunHours");
var systemLossFactorInput = document.getElementById("systemLossFactor");
var resultDiv = document.getElementById("result");
var panelWattage = parseFloat(panelWattageInput.value);
var numberOfPanels = parseFloat(numberOfPanelsInput.value);
var peakSunHours = parseFloat(peakSunHoursInput.value);
var systemLossFactor = parseFloat(systemLossFactorInput.value);
// Clear previous results and errors
resultDiv.innerHTML = ";
// Input validation
var isValid = true;
if (isNaN(panelWattage) || panelWattage <= 0) {
panelWattageInput.style.borderColor = "red";
isValid = false;
} else {
panelWattageInput.style.borderColor = "#ccc";
}
if (isNaN(numberOfPanels) || numberOfPanels <= 0) {
numberOfPanelsInput.style.borderColor = "red";
isValid = false;
} else {
numberOfPanelsInput.style.borderColor = "#ccc";
}
if (isNaN(peakSunHours) || peakSunHours <= 0) {
peakSunHoursInput.style.borderColor = "red";
isValid = false;
} else {
peakSunHoursInput.style.borderColor = "#ccc";
}
if (isNaN(systemLossFactor) || systemLossFactor 1) {
systemLossFactorInput.style.borderColor = "red";
isValid = false;
} else {
systemLossFactorInput.style.borderColor = "#ccc";
}
if (!isValid) {
resultDiv.innerHTML = 'Please enter valid numbers for all fields.';
resultDiv.style.backgroundColor = '#ffc107'; // Warning yellow
return;
}
// Calculate total system wattage
var totalWattage = panelWattage * numberOfPanels;
// Calculate daily energy production in Wh
var dailyProductionWh = totalWattage * peakSunHours * systemLossFactor;
// Convert to kWh
var dailyProductionKwh = dailyProductionWh / 1000;
// Calculate monthly production
var monthlyProductionKwh = dailyProductionKwh * 30; // Assuming an average of 30 days per month
// Format the output
var formattedDaily = dailyProductionKwh.toFixed(2);
var formattedMonthly = monthlyProductionKwh.toFixed(2);
resultDiv.innerHTML = formattedDaily + ' kWh per day';
resultDiv.innerHTML += 'Approximately ' + formattedMonthly + ' kWh per month';
// Ensure the result div is styled correctly if calculation is successful
resultDiv.style.backgroundColor = 'var(–success-green)';
}