We can quantify the electricity a solar panel generates using a few different terms. Let’s use an analogy of water falling from a great height to help unpack them:

Voltage (volts) is the electrical pressure that makes electrons flow if a path is available. Think of it like the height from which water held in a raised cup could fall. A greater height means more potential “pressure” or “push” even if the water isn’t currently flowing.

A cup of water is held high over a second almost empty cup, representing voltage.

Current (amps or milliamps) is the rate of electron flow that occurs when electrons are actively moving through a circuit. Imagine it as the amount of water actually flowing from the high cup to the low one.

Water flows from the high cup to the low cup, representing current (flow rate).

Power (watts) is the rate at which the voltage and current do work! It’s how much “oomph” your panel produces. Think about how falling water might spin a water wheel. The wheel’s speed is determined by the combined effect of the water’s height (representing voltage) and its flow rate (representing current).

Water flowing from a high cup to a lower cup turns a water wheel as it falls, representing power (work being done by the flow).

We can therefore calculate power using this equation:

Power = Voltage × Current

When direct sunlight excites more electrons, it creates a higher current. More current means your solar panel generates more power! The goal of a solar panel, especially one that moves, is to generate the most power possible.

In the next part of this lesson, you’ll start building your own solar panel system and put these concepts into practice!