Which unit is used to measure irradiance?

Irradiance is a measure of the power of solar radiation received on a surface per unit area, and it is expressed in terms of Watts per square meter (W/m²). This unit indicates how much solar power is available at a specific location and is essential for evaluating the performance and efficiency of solar energy systems. By measuring irradiance, one can understand how much sunlight is hitting a solar panel, which directly affects the amount of electricity generated.

While Watts measures power, Amperes measures electric current and Volts measures electric potential, neither of these units provide information about the spatial aspect of solar radiation reception. The use of W/m² conveys both the power (in Watts) and the area (in square meters) over which that power is distributed, which is crucial for applications in solar energy.