Solar Panel Calculator
Estimate the number of solar panels needed for your home.
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Estimate Your Home's Solar Needs
Considering a switch to solar power? This calculator helps you estimate the number of solar panels and the required system size (in kilowatts, kW) for your home. By inputting your average monthly energy consumption and the peak sun hours your area receives, you can get a good starting point for planning your solar installation.
The Formula Explained
- Daily Energy Use:
Daily kWh = Monthly kWh / 30 - Required System Size (DC):
System Size (kW) = Daily kWh / Peak Sun Hours - Number of Panels:
Number of Panels = (System Size in Watts) / (Wattage per Panel)
How to Use the Calculator
- Monthly Energy Consumption (kWh): Find this on your electricity bill.
- Peak Sun Hours per Day: This is the average number of hours per day that your location receives sunlight at an intensity that is optimal for solar panels. This varies greatly by location (e.g., Arizona might get 6-7, while Seattle might get 3-4).
- Solar Panel Wattage: Enter the wattage of the panels you are considering (a common size is 340-400W).
Real-World Example
A household uses 900 kWh of electricity per month. They live in an area that gets an average of 5 peak sun hours per day. They plan to use 400W panels.
- Daily kWh:
900 / 30 = 30 kWh - System Size:
30 kWh / 5 hours = 6 kW(or 6,000 Watts) - Number of Panels:
6,000 W / 400 W per panel = 15 panels
Frequently Asked Questions (FAQ)
- What are 'peak sun hours'? It's not just the number of daylight hours. It's an equivalent measure of how many hours of peak, direct sunlight a location receives. You can find this data for your city with an online search.
- Does this calculator account for efficiency losses? No. Real-world systems have efficiency losses from inverters, wiring, and panel degradation. It's common to oversize a system by about 15-25% to account for these factors.
- Is this all I need to know to go solar? No. This is a preliminary estimate. A professional solar installer will conduct a detailed site assessment, analyze your roof's orientation and shading, and review local utility policies to design a system that's right for you.