Calculating the potential energy output of a photovoltaic (PV) solar system is crucial for understanding its economic viability and environmental impact. This calculator helps estimate the annual energy production based on key system parameters and environmental factors. The primary goal is to determine the kilowatt-hours (kWh) of electricity a solar panel system can generate over a year.
Key Input Parameters Explained:
Desired System Size (kWp): This is the rated peak power output of the solar panels themselves under standard test conditions (STC). It's often referred to as the 'nameplate' capacity and is measured in kilowatts-peak (kWp). For example, a system with four 330W panels would have a total kWp of 4 * 0.330 = 1.32 kWp.
Location Type: This factor accounts for the typical environmental conditions affecting solar generation. 'Urban' locations often have more obstructions (buildings, trees) leading to more shading, while 'Rural' locations tend to have fewer. This is represented by a 'Performance Ratio' or 'Loss Factor' multiplier. Higher values indicate better performance.
Average Daily Peak Sun Hours: This is a crucial metric representing the equivalent number of hours per day when solar irradiance averages 1000 W/m². It's not simply the number of daylight hours but a measure of the intensity of sunlight. Values vary significantly by geographic location and season.
System Losses (%): Real-world solar systems experience losses due to various factors, including temperature, soiling (dirt on panels), shading, inverter inefficiency, wiring resistance, and panel degradation over time. This percentage quantifies these combined losses.
How the Calculation Works:
The estimated annual energy production (in kWh) is calculated using the following formula:
Estimated Annual Production (kWh) = System Size (kWp) * Average Daily Peak Sun Hours * 365 days/year * Location Factor * (1 - System Losses / 100)
Example Breakdown:
System Size: Let's assume a 5 kWp system.
Location Type: Suburban (factor = 1.25).
Average Daily Peak Sun Hours: 4.5 hours.
System Losses: 15%.
Calculation:
5 kWp * 4.5 hours/day * 365 days/year * 1.25 (Location Factor) * (1 - 15 / 100)
= 5 * 4.5 * 365 * 1.25 * 0.85
= 22,279.6875 kWh per year (approximately 22,280 kWh)
This result indicates that a 5 kWp system, under these specific conditions, could generate around 22,280 kWh of electricity annually.
Use Cases:
This calculator is valuable for:
Homeowners and businesses considering a solar installation to estimate potential energy savings and system performance.
Solar installers providing preliminary estimates to potential clients.
Educational purposes to understand the factors influencing solar energy generation.
Comparing the potential output of different system sizes or locations.
Disclaimer: This is an estimated calculation. Actual production can vary based on specific site conditions, installation quality, equipment used, weather patterns, and maintenance.
function calculateSolarProduction() {
var systemSize = parseFloat(document.getElementById("systemSize").value);
var locationFactor = parseFloat(document.getElementById("locationType").value);
var avgSunHours = parseFloat(document.getElementById("averageDailySunHours").value);
var systemLossesPercent = parseFloat(document.getElementById("systemLossesPercentage").value);
var resultValueElement = document.getElementById("result-value");
var resultUnitElement = document.getElementById("result-unit");
// Input validation
if (isNaN(systemSize) || systemSize <= 0) {
resultValueElement.textContent = "Invalid Size";
resultUnitElement.textContent = "";
return;
}
if (isNaN(avgSunHours) || avgSunHours < 0) {
resultValueElement.textContent = "Invalid Sun Hours";
resultUnitElement.textContent = "";
return;
}
if (isNaN(systemLossesPercent) || systemLossesPercent 100) {
resultValueElement.textContent = "Invalid Losses";
resultUnitElement.textContent = "";
return;
}
// Calculation
var annualProduction = systemSize * avgSunHours * 365 * locationFactor * (1 – systemLossesPercent / 100);
// Display result, formatted to 2 decimal places
resultValueElement.textContent = annualProduction.toFixed(2);
resultUnitElement.textContent = "kWh";
}