Solar Array Sizing Calculator
Calculation Results:
Required System Size: — kWp
Estimated Number of Panels: —
Estimated Annual Energy Production: — kWh/year
Estimated Roof Area Needed: — sq ft
Error: Please enter valid positive numbers for all fields. System Loss must be between 0 and 100.
'; return; } var systemLossFactor = systemLoss / 100; // Convert percentage to decimal // 1. Calculate Required DC System Size (kWp) // Target AC production is the daily energy consumption var targetDailyACProduction = dailyEnergyConsumption; // Daily DC production needed, accounting for system losses var dailyDCProductionNeeded = targetDailyACProduction / (1 – systemLossFactor); // Required system size in kWp var requiredSystemSizeKW = dailyDCProductionNeeded / peakSunHours; // 2. Calculate Number of Panels var requiredSystemSizeWatts = requiredSystemSizeKW * 1000; var numPanels = Math.ceil(requiredSystemSizeWatts / panelWattage); // 3. Calculate Estimated Annual Energy Production (kWh/year) // Use the actual system size based on the rounded-up number of panels var actualSystemSizeKW = (numPanels * panelWattage) / 1000; var annualEnergyProduction = actualSystemSizeKW * peakSunHours * 365 * (1 – systemLossFactor); // 4. Calculate Estimated Roof Area Needed var estimatedRoofArea = numPanels * panelArea; // Display results document.getElementById('requiredSystemSize').innerHTML = 'Required System Size: ' + requiredSystemSizeKW.toFixed(2) + ' kWp'; document.getElementById('numberOfPanels').innerHTML = 'Estimated Number of Panels: ' + numPanels + ''; document.getElementById('annualEnergyProduction').innerHTML = 'Estimated Annual Energy Production: ' + annualEnergyProduction.toFixed(0) + ' kWh/year'; document.getElementById('estimatedRoofArea').innerHTML = 'Estimated Roof Area Needed: ' + estimatedRoofArea.toFixed(0) + ' sq ft'; document.getElementById('solarResult').style.backgroundColor = '#e9f7ef'; // Reset background color on successful calculation document.getElementById('solarResult').style.borderColor = '#d4edda'; document.getElementById('solarResult').style.color = '#155724'; }Understanding Your Solar Array Sizing
Planning a solar energy system for your home or business involves more than just picking panels. It requires careful calculation to ensure your system meets your energy needs efficiently. Our Solar Array Sizing Calculator helps you estimate the key components of your potential solar setup.
How the Calculator Works
This tool uses several critical inputs to determine the optimal size and number of solar panels for your specific situation:
- Average Daily Energy Consumption (kWh/day): This is the most crucial input. It represents how much electricity your household or business uses on an average day. You can usually find this on your electricity bills (often listed as "kWh used" or similar). The higher your consumption, the larger your solar array will need to be.
- Average Peak Sun Hours (hours/day): Also known as "full sun hours," this is a measure of the intensity of sunlight in your location. It's not just the total hours the sun is up, but the equivalent hours of direct, full-intensity sunlight. This value varies significantly by geographic location and season. Online resources or local solar installers can provide accurate peak sun hour data for your area.
- Individual Panel Wattage (Watts): This refers to the power output 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 system size.
- System Loss Factor (%): No solar system operates at 100% efficiency. Losses occur due to various factors like inverter efficiency, wiring resistance, temperature effects, dust, shading, and degradation over time. A typical system loss factor ranges from 10% to 25%. Our calculator uses a default of 15%, but you can adjust it based on your specific system components and site conditions.
- Individual Panel Area (sq ft): This is the physical footprint of a single solar panel. Knowing this helps estimate the total roof area required for your system. A common residential panel might be around 18 sq ft (e.g., 6 ft x 3 ft).
Understanding the Results
Once you input your data, the calculator provides the following key outputs:
- Required System Size (kWp): This is the total peak power output your solar array needs to generate to meet your daily energy consumption, accounting for system losses and peak sun hours. 'kWp' stands for kilowatt-peak, indicating the maximum power output under ideal conditions.
- Estimated Number of Panels: Based on the required system size and the wattage of individual panels, this tells you how many panels you'll likely need. The calculator rounds up to ensure sufficient coverage.
- Estimated Annual Energy Production (kWh/year): This is the total amount of electricity your system is expected to generate over a year, providing a clear picture of your potential energy savings and environmental impact.
- Estimated Roof Area Needed (sq ft): This helps you determine if you have enough suitable roof space (or ground space) to accommodate the estimated number of panels.
Example Calculation:
Let's say you have an average daily energy consumption of 30 kWh/day, live in an area with 5 peak sun hours/day, plan to use 400 Watt panels, anticipate a 15% system loss, and each panel is 18 sq ft.
- Required System Size: Approximately 7.06 kWp
- Estimated Number of Panels: 18 panels (7.06 kWp * 1000 W/kWp / 400 W/panel = 17.65, rounded up to 18)
- Estimated Annual Energy Production: Approximately 11,198 kWh/year
- Estimated Roof Area Needed: 324 sq ft (18 panels * 18 sq ft/panel)
This calculator provides a strong starting point for your solar journey. For precise planning and installation, always consult with a professional solar installer who can conduct a detailed site assessment and provide a customized proposal.