Definition: Power output refers to the instantaneous rate at which a solar panel converts sunlight into electricity. It's measured in watts (W) or kilowatts (kW).

Analogy: Think of it like the speed of a car at a specific moment.

Measurement: It's what you would measure with a multimeter connected to the panel's output terminals at any given time.

Standard Test Conditions (STC): Solar panel power output is typically rated under Standard Test Conditions (STC), which are defined as:

Nominal Power: The power output rating you see on a solar panel's datasheet (e.g., 400 W) is its nominal power, measured under STC.

Real-World Variation: In the real world, power output fluctuates constantly depending on factors like sunlight intensity, temperature, shading, and the panel's orientation.