Solar Panel Output Calculator
Calculate expected daily energy production from your solar panels
Inputs
Rated wattage of your solar panel
Accounts for heat, wiring, controller losses
Panel sizes
Efficiency factors
Daily output (200W panel)
How to use this calculator
- 1Enter the rated wattage of your solar panel
- 2Enter how many panels you have
- 3Adjust peak sun hours for your location
- 4Set system efficiency (accounts for real-world losses)
Understanding solar output
Solar panels rarely produce their rated wattage. Real-world output depends on sun angle, temperature, shading, and system losses.
A 200W panel might only produce 160-170W under real conditions. The 80% efficiency factor accounts for heat, wiring, and controller losses.
Seasonal variation is significant. Winter output can be 30-50% of summer production due to shorter days and lower sun angles.
Frequently asked questions
Why don't panels produce their rated wattage?
Panel ratings are measured under ideal lab conditions (1,000W/m², 25°C). Real-world output is typically 75-85% of rated wattage due to heat, angle, shading, and system losses.
How do I find peak sun hours for my location?
Use NREL's PVWatts tool or solar irradiance maps. General ranges: Southwest US (5-7 hrs), Southeast (4-5 hrs), Northeast (3-4 hrs). These vary significantly by season.
Can I combine different wattage panels?
Yes, but it's not ideal. Mismatched panels should be connected to separate charge controllers or use micro-inverters. Otherwise, the lowest-performing panel limits the array.
Result
800Wh
Expected daily production