Solar Panel Wattage Calculator

Find a solar panel's rated wattage.

Rated power (W) 320

Formula: watts = efficiency * area * irradiance / 100

Step-by-step with your numbers:

1. Values used:

2. Panel efficiency = 20 %

3. Panel area = 1.6 m2

4. Solar irradiance = 1,000 W/m2

6. Rated power = 320W

Did we solve your problem today?

A solar panel's wattage is its efficiency times its area and the sun's power.

The math behind it

rated watts = efficiency x area x irradiance (typically 1000 W/m^2 at standard test conditions).

A 20% efficient 1.6 m^2 panel under standard sunlight produces 320 W.

Why does it say 1000 W/m^2?

That is the standard test irradiance — peak sun on a clear day.